EPA-600/2-78-054
March 1978
Environmental Protection Technology Series
FIELD AND LABORATORY METHODS APPLICABLE
TO OVERBURDENS AND MINESOILS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-78-051*
March 1978
FIELD AND LABORATORY METHODS APPLICABLE
TO OVERBURDENS AND MINESOILS
Andrew A. Sdbek, William A. Schuller,
John R. Freeman, and Richard M. Smith
West Virginia University
In Cooperation with the West Virginia
Geological and Economic Survey
Morgantown, West Virginia 26506
Grant No. R803508-01-0
Project Officer
Elmore C. Grim
Resource Extraction and Handling Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 1*5268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 1*5268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection
Agency, nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
11
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FOREWORD
When energy and material resources are extracted, processed, converted and
used, the related pollutional impacts on our environment and even our health
often require that new and increasingly more efficient pollution control
methods are used. The Industrial Environmental Research Laboratory -
Cincinnati (lERL-Ci) assists in developing and demonstrating new and improved
methodologies that will meet those needs both efficiently and economically.
This report provides chemical, physical, mineralogical, and microbiological
procedures for the analysis of coal overburdens and the resultant minesoils.
These step-by-step methods identify and measure rock and soil properties
that influence advance planning, mining efficiency, post-mining land and
water quality and long range land use.
Rock and soil property measurements will be especially useful to State and
Federal agencies, private contractors, and mining firms who require detailed
information for pre-mining planning and projections of future results expec-
ted under specified management. For further information contact the
Extraction Technology Branch of the Resource Extraction and Handling Division.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
ill
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ABSTRACT
With the growing demand for environmental assessment of a mining site, it
becomes apparent that a manual of field and laboratory procedures to study
the overburden and the resulting minesoil is necessary.
Incorporated vithin this manual are step-by-step procedures on field
identification of common rocks and minerals; field sampling techniques;
processing of rock and soil samples; and chemical, mineralogical, micro-
biological, and physical analyses of the samples. The methods can be used
by mining companies, consultant firms, and State and Federal agencies to
insure mining efficiency, post-mining land and water quality and long range
land use.
Inherent to these methods is the definition of terms. Many common terms
are used inconsistently even within small groups; and when multiple disci-
plines are involved, communication demands that many terms must be defined
for that particular purpose. Thus, the definition of essential rock, soil,
chemical, mineralogical, microbiological, and physical terms constitute an
important part of this project.
This report was submitted in fulfillment of Project R803508-01-0 by West
Virginia University under the sponsorship of the U.S. Environmental
Protection Agency. Work was completed as of December, 1976.
IV
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CONTENTS
Foreword
Abstract iv
List of Figures viii
List of Tables ix
Abbreviations , x
Acknowledgments xi
1. Introduction, Units, Conversions, and Preplanning 1
1.1 Introduction 1
1.2 Units and Conversions 2
1.3 Preplanning Total Mining Operation * 3
1.3.1 Acid-Base Account 3
1.3.2 Geologic and Soil Considerations U
8
2. Field Clues and Sampling Methods 8
2.1 What to Look for and Measure in the Field 8
2.1.1 Summary 8
2.1.2 Soil Horizons and Rock Types 12
2.1.3 Color 17
2.1.H Rock Hardness 19
2.1.5 Presence of Calcareous Material 20
2.1.6 Texture, Pyrite, and Mica 21
2.1.7 Other Soil and Rock Features 22
2.1.8 Texture by Feel 23
2.2 Overburden Sampling and Labeling 25
2.2.1 Summary 25
2.2.2 Blast Hole Sampling 26
2.2.3 Sampling from Exploration Cores 28
2.2.U Hand Sampling of High Wall 30
2.2.5 Selective Sampling 32
2.2.6 Labeling Samples 33
2.3 Minesoils 3!*
2.3.1 Describing Minesoil Profiles 3U
2.3.2 Sampling for Classification and Fertility 37
3. Sample Processing and Laboratory' Analyses Ill
3.1 Characterizing, Subsampling, and Crushing Samples Hi
3.1.1 Characterizing Samples In
3.1.2 Subsampling and Grinding Rock and Native Soil
Samples It 2
3.1.3 Subsampling and Grinding Minesoil Samples 1*3
3.2 Chemical Methods 1*5
3.2.1 Summary 1*5
3.2.2 pH 1*5
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3.2. 3 Neutralization Potential ............................ U7
3.2.U Total Sulfur ........................................ 51
3.2.5 Sodium Bicarbonate Extractable Phosphorus ........... 56
3.2.6 Acid-Extractable and Non-Extractable Sulfur ......... go
3.2.7 Lime Requirement (Ca(OH)2 Titration) ................ 63
3.2.8 Lime Requirement ( 5 Minute Boiling ) ................. 6U
3.2.9 Lime Requirement (Woodruff Buffer) .................. 65
3.2.10 Lime Requirement (S.M.P. Buffer) .................... 67
3.2.11 Total Sulfur Estimation by Peroxide Oxidation ....... 69
3.2.12 Double Acid Extractable Nutrients ................... 72
3.2.13 Organic Carbon (Walkley-Black) ...................... 78
3.2. Ik Organic Carbon (ignition) ........................... 80
3.2.15 Total Nitrogen (Kjeldahl) ........................... 8l
3.2.16 Calcium Saturation CEC .............................. 85
3.2.17 Sodium Saturation CEC ............................... 88
3.2.18 Electrical Conductance of Soil Extract .............. 91
3.2.19 Sodium Absorption Ratio ...... ................... .. . . . 95
3. 3 Mineralogical Methods ...................................... 99
3.3.1 Summary ............................................. 99
3.3.2 Identification of Grains (immersion) ................ 100
3.3.3 Petrographic Analysis of Thin Sections .............. 105
3. 3. U Clay Minerals by X-Ray Diffraction ............ ...... 108
3. U Physical Methods ........................................... 117
3. U . 1 Summary ............................................. 117
3.U.2 Partical Size Analysis (Pipette) .................... 117
3. U. 3 Particle Size Analysis (Hydrometer) ................. 122
3.U.U Bulk Density (Core Method) .......................... 125
3.U.5 Bulk Density (Saran Method) ......................... 127
3.U.6 Bulk Density (Varsol Method) ........................ 131
3. U. 7 Bulk Density (Sand Method) .......................... 135
3.U.8 Particle Density .................................... lUl
3.U.9 Porosity ............................................ iU3
3.U.10 Free Swelling ....................................... lUU
3.U.11 Moisture Retention (Pressure Plate) ................. lU6
3.U.12 Moisture Retention (Pressure Membrane) .............. 150
3. 5 Microbiological Methods .................................... 15 1).
3.5-1 Summary ............................................. 15U
3.5.2 Buried Slide Technique .............................. 155
3.5.3 Total Microbial Count ( Agar Plate ) .................. l6o
3.5.U MPN of Aerobic Cellulose-Decomposing Bacteria ....... 1614.
3.5-5 Carbon Dioxide Production ........................... 168
3.5.6 MPN of Sulfur-Oxidizing Bacteria .................... 172
It. Short Term and Simulated Weathering .............................
U.I Laboratory and Field Methods ............................... 17U
U . 1 . 1 Summary ............................................. 17U
U.I. 2 Slaking ............................................. 175
U.I. 3 Physical Weathering Potential ....................... 176
U.l.U Modified Sieve Analysis ............................. l8o
U.I. 5 Humidity Cells ...................................... 182
U.I. 6 Weathering Plots .................................... 185
VI
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References 189
Publications 19**
Glossary ^ 196
vii
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FIGURES
Number Page
1 Acid-Base Account of the Kentucky No. 11 and No. 12 Coal
Overburden 5
2 Highwall Showing High and Low Chroma Color Characteristics... 9
3 Pittsburgh-Redstone Overburden Showing Yellowboy Staining
the Limestone Between the Coal Seams 10
U Pittsburgh-Redstone Overburden Showing Extreme Yellowboy
Staining on a Calcareous Mudstone Below the Pittsburgh
Coal Seam 11
viii
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TABLES
Number Page
1 Volume and Normality of Hydrochloric Acid Used for Each
Fizz Rating .............................................. 50
2 Standards for Sodium Bicarbonate Extract able
Phosphorous ............................................ . . 59
3 Soil-SMP Buffer pH and Corresponding Lime Requirement
(L.R. ) to Bring Material to pH 6.5 ....................... 69
k Phosphorous (P) Standards ................................ 75
5 Calcium (Ca) Standards ................................... 77
6 Magnesium (Mg ) Standards ................................. 77
7 Standards for Calcium CEC Determination .................. 88
8 Calcium and Magnesium Standards for Sodium-Adsorption
Ratio [[[ 99
9 Basal Spacings of Clay Minerals as Influenced by Mg-
Saturation and Glycerol Treatments ....................... 115
10 Basal Spacings of Clay Minerals as Influenced by K-
Saturation and Heat Treatments ........................... 116
11 Times for Particle Size Analysis (Pipette Method) Based
on Temperature ........................................... 121
12 Volume of Water Per Gram Based on Temperature
13 Most-Probable-Numbers for use with 10-Fold Dilutions and
5 Tubes Per Dilution ..................................... 167
Ik Factors for Calculating the Confidence Limits for the
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ABBREVIATIONS
a
cc
CEC
cm
ft
S
in
kg
km
1
Ib
m
M
meq_
meq./100g
mg
min
ml
TCTm
mmhos/cm
MPN
I
nm
oz
ppm
pp2m
at
1°
psi
RPM
S.M.P.
t
acre(s)
cubic centimeter(s)
Cation Exchange Capacity
centimeter(s)
foot (feet)
gram(s)
inch(es)
kilogram(s)
kilometer(s)
liter(s)
pound(s)
meter(s)
Molar
milliequivalent(s)
milliequivalents per 100 grams
milligram(s)
minute(s)
milliliter(s)
millimeter(s)
millimhos per centimeter
Most Probable Numbers
Normal
nanometer(s)
ounce(s)
parts per million
parts per 2 million
percent
pounds per square inch
revolutions per minute
Shoemaker, McLean, and Pratt
ton(s)
x
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ACKNOWLEDGMENTS
The following organizations have assisted in this work: West Virginia
Steering Committee for Surface Mine Research; West Virginia Surface
Mine and Reclamation Association; West Virginia Department of Natural
Resources; West Virginia Geological and Economic Survey; United States
Department of Agriculture, Soil Conservation Service; and a number of
mining companies whose employees provided active cooperation that made
this study possible.
Valuable consultation and advice were provided by: Alan C. Donaldson,
Frank W. Glover, Walter E. Grube, Jr., Everett M. Jencks, John J. Renton,
John C. Sencindiver, and Rabindar N. Singh.
The following people participated in the preparation of this report:
Thomas Arkle, Jr., Carlos P. Cole, John R. Freeman, Milton T. Heald,
Eric F. Perry, William A. Schuller, Richard Meriwether Smith, Andrew
A. Sobek, Ronnie L. Taylor, and Harold A. Wilson.
Assistants in the field and laboratory work included: Sammy L. Baldwin,
Shelia A. McFarland, Robert A. Philips, and Alfred N. Wickline.
For the reader who may have need to confer with the authors of
individual major topics, the following list is provided:
Introduction, Units, Conversions, and Preplanning (Arkle, Smith,
Sobek).
What to Look For and Measure in the Field (Freeman, Perry,
Schuller, Smith, Sobek, Taylor).
Overburden Sampling and Labeling (Freeman, Perry, Schuller, Smith,
Sobek).
Minesoils (Freeman, Sencindiver, Smith, Sobek).
Characterizing, Subsampling, and Crushing Samples (Freeman, Perry,
Schuller, Sobek).
Chemical Methods (Freeman, Schuller, Smith, Sobek).
Mineralogies! Methods (Heald, Schuller).
Physical Methods (Perry, Schuller, Sobek').
Microbiological Methods (Schuller, Smith, Wilson).
xi
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Short Term and Simulated Weathering (Freeman, Schuller, Smith,
Sobek, Taylor).
The support of the project by the Office of Research and Development,
U.S. Environmental Protection Agency, and the help provided by Robert B.
Scott in finalizing this report; Elmore C. Grim, Grant Project Officer;
and Ronald D. Hill is gratefully acknowledged.
xii
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SECTION 1
INTRODUCTION, UNITS, CONVERSIONS, AND PREPLANNING
1.1 INTRODUCTION
Studies of coal overburdens and mlnesoils in relation to environmental
quality have progressed to the point that needed appraisals can be made with
confidence if adapted and calibrated procedures are followed in the field
and the laboratory. This manual contains such procedures. They are des-
cribed in a step-by-step manner that should assure consistency of results.
These procedures include everything from identification of common rocks
and minerals in the field through interpretation of analytical results.
When a manual is to be used by many different disciplines, many terms
must be defined for a particular purpose or misunderstandings result.
Insofar as the application of this manual is concerned, essential rock,
soil, chemical, physical, and engineering terms have been defined. Outside
of the manual, other meanings may be attached to these terms.
This manual consists of four major sections: Section 1 introduces the
manual and contains the advance planning approach; Section 2 contains all
procedures and clues to be used in the field; Section 3 is strictly labora-
tory methods; and Section k is a combination of both field and laboratory
weathering methods.
Each section is subdivided into specific groupings of closely related
material. In turn, these subsections are subdivided into individual pro-
cedures. They are numbered so that cross referencing within and between
sections, subsections, and procedures can be done easily and specifically.
If one part of a procedure is referenced (i.e. see 3.2.2.2), the first
number indicates the section and the second number indicates a specific
grouping. The third number indicates a particular method while the fourth
number refers to a certain part of that method.
An example of the numbering system is as follows:
Section 3.2.2.2
Sample Processing and Laboratory Analysis,
Chemical Methods.
PH
.Comments.
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1.2 UNITS AND CONVERSIONS
To Convert
To
Multiply By
acre
centimeters
feet
gallons (U.S. llq. )
grams
grams
hectare
inches
kilograms
kilometers
Ib/acre
liters
liters
miles
milliliters
millimeters
meters
meters
ounces
pounds
ppm .
section (l sg. mile)
OF
°c
hectare
inches
meters
liters
pounds
kilograms
acre
centimeters
grams
miles
ppm
gallons (U.S. liq.. )
milliliters
kilometers
liters
meters
feet
millimeters
liters
grams
Ib/acre
acres
°c
°F
O.UOVT
0.3937
0.30U8
3.785306
0.002205
0.001
2.U71
2.5^0
1000.0
0.6211*
0.5
0.26U179U
1000.0
1.609
0.001
0.001
3.281
1000.0
0.02957
1*53.6
2.0
6i*o
5/9 (°F-32)
(9/5 °C) + 32
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1.3 PREPLANNING TOTAL MINING OPERATION
1.3.1 Acid-Base Account
In the humid areas of the United States, the toxicity associated with acid
results largely from the oxidation of iron disulfides. This process takes
place when earth disturbance activities such as mining (Temple and Koehler,
195U; Hill, 1970) and highway construction (Miller et al., 1976) expose iron
disulfides to the atmosphere. Since the public in the United States has
supported legislation that acid-toxic or potentially toxic materials
(a source of pollution) will not be left exposed, the need for a basis to
evaluate overburden materials arose.
Acid-base accounting is a dependable criterion by which overburden materials
can be evaluated. An acid-base account consists of two measurements:
(l) total or pyritic sulfur and (2) neutralization potential. The
accounting balances maximum potential acidity (from immediately titratable
sources plus sulfuric acid equivalent calculated from total sulfur) against
total neutralizers (from alkaline carbonates, exchangeable bases, weather-
able silicates or other rock sources capable of neutralizing strong acids
as measured by the neutralization potentials).
The total or pyritic sulfur content (see 3.2.J-0 accurately quantifies
potential acidity of materials when all sulfur is present as a pyritic
mineral. When gypsum is found in an overburden sample or the materials
are weathered, sulfur occurs in the form of sulfates. Samples high in
organic carbon usually contain organic sulfur. When part of the sulfur
occurs in nonacid-producing forms, the maximum potential acidity as calcu-
lated will be too high. It is for this reason that such calculations are
referred to as maximums and that in doubtful cases appropriate acid and
water leachings should be made to rule out those forms of sulfur which do
not produce acid (see 3.2.6). Then from the stoichiometric equation of
pyrite oxidation, the maximum potential acidity can be calculated in terms
of calcium carbonate equivalent. Overburden material containing 0.1$
sulfur (all as pyrite) yields an amount of sulfuric acid that requires
3.125 tons of calcium carbonate to neutralize one thousand tons of the
material. The neutralization potential (see 3.2.3) of overburden materials,
the second component of a net acid-base account, measures the amount of
neutralizers present in the overburden materials. This measurement is
found by treating a sample with a known amount of standardized hydrochloric
acid, heating to assure complete reaction, and titrating with a standardized
base. The result is then expressed in calcium carbonate equivalents. When
balanced against acidity from the total sulfur measurement, a net acid-base
account can be made.
From the acid-base account, potentially toxic material is defined as any
rock or earth material having a net potential deficiency of 5.0 tons of
calcium carbonate equivalent or more per 1000 tons of material. The 1000
tons is based on the assumption that an acre plow-layer contains 2 million
pounds of soil. Regardless of the acid-base account, materials which have
a pH of less than 4.0 in a pulverized rock slurry in distilled water are
defined as being acid-toxic.
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The choice of the deficiency of 5 tons of calcium carbonate equivalent per
1000 tons of material as the division between toxic and non-toxic material
obviously is arbitrary. However, when applied to the large number of samples
studied during the past several years of minesoil research at West Virginia
University, it corresponds to other supporting laboratory information about
these samples as well as to extensive field experiences with minesoils
developing in the different rock types. If rock or soil samples were defined
to be toxic at much lower calcium carbonate equivalent deficiencies than 5
tons per 1000 tons, we would be declaring many of our native soils to be
toxic. On the other hand, with deficiencies much greater than 5 tons per
1000 tons, toxic concentrations of piant-available aluminum and pH values
below U.O often develop rapidly.
Rock type is incorporated with the acid-base account because it is useful
to categorize the materials which comprise coal overburdens. Knowledge of
the rock types can provide an estimate of the texture and base status of
a future minesoil, as well as stability of rock fragments. For example,
sandstones containing moderate amounts of pyrite and lacking sufficient
neutralizers become active acid producers when exposed to the atmosphere.
The properties previously discussed are represented graphically in Figure 1.
There are two zones of acid-toxic materials (the l6.2 to 17-1 m and the 20.7
to 21.6 m depths) indicated by pH values of less than U.O. Both zones
contain enough sulfur to continue to overwhelm the small amount of neutra-
lizers present. Thus, these materials have the potential for remaining
acid-toxic unless large amounts of neutralizers (50 and 80 tons calcium
carbonate equivalent per 1000 tons of material, respectively) are added.
In addition, there is a zone of potentially toxic material at a depth of
13. U to 16.2 m and two zones below the 23 m depth (underlying the first
coal and overlying the bottom coal), which are defined by a calcium carbonate
deficiency of more than 5 tons per 1000 tons of material even though the pH
is above U.O.
Non-toxic zones, which exhibit varying amounts of excess neutralizers, exist
from the surface to a depth of 13.U m, from the 17.1 to 21 m depth, and
from the 2k.k to 25.^ m depth. These materials can be removed and replaced
in sequential order, selectively blended before replacement, or totally
blended before replacement. Other methods of handling the overburden
materials would include utilization of the limestone, after crushing, as a
source of neutralizers to be blended with the potentially toxic materials.
The acid-base accounting method provides a useful tool for evaluating over-
burdens in the humid areas of the United States, since it is useless to look
for plant toxicities from elements such as aluminum, boron, etc., until the
acid problem is eliminated.
1.3.2 Geologic and Pedologic Considerations
The decision of management to open and operate a strip mine is based on
numerous considerations involving mining engineers, geologists, agronomists
and other reclamation specialists. Initial considerations of prospective
stripping areas include accessibility, proximity to markets, uniformity,
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DEFICIENCY
EXCESS
% SULFUR
COAL
v.. .
1000
10 6 4 21 I 2 46 10
CaC03 EQUIVALENT;
(TONS/THOUSAND TONS of MATERIAL)
100
looo
468
PH
Figure 1. Acid-base account of the Kentucky no. 11 and no. 12 coal
overburden. '
thickness, quality and quantity of coal seams, and physical and chemical
characteristics of the overburden materials for use in reclamation. In
recent years the prospect of successful reclamation of mined lands resulting
from selective placement of non-toxic, nutrient-rich overburden materials
has become increasingly important in the decision to locate and develop new-
strip mines. -• ••
Coal-bearing overburden bedrock in the Appalachian and Midwestern coal basins
commonly consists of a complex series of mudrocks and sandstones interbedded
with generally thinner, more regular beds of limestone> carbolith, coal, and
coal undersoil. The predominate mud and sand rock stratigraphic units often
change rapidly in short distances (laterally and/or vertically) as compared
with the chemical (limestone) and organic (coal) deposits. Usually, the
rock units are mixtures in varying proportions of the common sedimentary
rock types. In addition, trace amounts of heavy minerals occur in all
sedimentary rocks. Of these minerals, chemical studies of overburden
materials are most concerned with concentrations of•the potentially acid-
forming heavy metallic minerals, mostly iron disulfide, called pyritic
minerals.
The immediate and maximum acid-making potential of the rock types in the
overburden, is assayed by determining: (l) pH of the pulverized rock paste;
-------
(2) total or pyritic sulfur; and (3) neutralization potential. The first
determination gives the present condition of the rock types and the second
and third determinations forecast the potential net acid-base account of the
overburden materials (see 1.3.1).
Recognition of gross lateral rock changes indicates major physical and
mineralogic differences and suggests the presence of more subtle changes
that may be measured in an acid-base account of the overburden. In practice,
the physical character, mineral composition, and net acid-base account
provide information needed for desired mixing or placement of overburden
materials. Highly toxic overburden necessitates disposal by proper blending,
sandwiching, or burial with neutralizers. Non-toxic materials require proper
treatment guided by experience and adapted chemical tests.
Advance determination of the physical and chemical character of the over-
burden materials may mean the difference between economic success or failure
of a mining operation. Planned removal and direct placement of materials
with known properties can prevent mistakes that require re-handling or
costly reclamation practices.
A three-step approach is suggested for the study of overburden materials
during the investigation of the feasibility of development of a strip mine.
The three steps may be stated as follows:
1. Geological and soil reconnaissance.
2. Regional study of physical and chemical properties of soil profiles
and rock units of overburden materials as well as underlying coals.
3. Detailed analyses of appropriate samples to determine important
physical and chemical characteristics of soil horizons and rock
units of the overburden at promising sites.
Geological and soil reconnaissance in the area of interest consists of a
review of information from private, state and federal sources. Available
information is generally confined to modern standard soil surveys, 7.5
minute topographic maps, county geologic reports, physical and mineralogical
descriptions of rock units, chemical analyses of coals, and location of
underground mines, surface mines and coal prospects. Collection and
analysis of selected dominant soil profiles and rock units of prospective
overburden materials in the area of interest may offer early clues to
future land use and reclamation opportunities.
Delineation of the physical and chemical relationships of overburden
materials and associated coals is depicted by construction of generalized
cross sections similar to those in northern West Virginia and western
Maryland as illustrated in EPA reports 670/2-7U-070 (Smith et al., 197*0
and 600/2-76-18^ (Smith et al., 1976). Sampling of correlative rock units
can usually be obtained at exposures, abandoned and active surface mines,
or from drill cuttings and cores along or adjacent to the line of cross
section in areas of contour stripping. Cores and highwalls of active strip
mines are usually the only source of samples in environs of area stripping,
-------
which are often covered with unconsolidated deposits (e.g. loess, glacial
till, and outwash).
Collection of more closely spaced detailed geological and chemical data
continues during exploration of the proposed stripping site and also during
the stripping operation. Sources of geological information and samples are
cores, churn drill cuttings, blast hole cuttings, and exposures of excava-
tions and highwalls. Sampling sites should be spaced to give a three-
dimensional coverage of the area of stripping. The geologist-pedologist
describes the soil and lithologic units exposed or penetrated by the drill
in some detail. He samples the rock section either in arbitrary 30 cm
intervals or other appropriate intervals (see section 2.2) for chemical an^
physical analysis. Three-dimensional illustrations such as ribbon diagrams
(showing soil profiles and lithologic units plus acid-base or other
relationships) or isopachous maps (contouring thickness of separate litho-
logic units and weighted averages of acid-base relationships) can provide
interesting artistic views of problem areas to be encountered prior to
stripping. A similar exercise is the construction of a series of inter-
secting cross sections illustrating the overburden information derived
from all available sources. Such cross sections show a combined geologic
and chemical accounting of the overburden materials throughout the area to
be stripped. Intersecting cross sections provide the operator with a
pictorial view of the physical and chemical characteristic of the overburden
rock in advance of strip mining and guides the operator in the handling and
segregating of materials to ensure favorable minesoils and economical
reclamation for intended land use.
Following mining, the young minesoils are appropriate for classification into
classes based on properties. The mapping of soil classes and phases is
simplified by good advance information about overburdens and their placement
during mining. Short-term treatment and long-range management follow
established patterns once minesoil mapping units have been established and
delineated.
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SECTION 2
FIELD CLUES AND SAMPLING METHODS
2.1 WHAT TO LOOK FOR.AND MEASURE IN THE FIELD
2.1.1 .Summary f
Procedures in this section aid the field observer. As one looks at an .
overburden column, prominent characteristics observed include changes in .
color, soil horizons, rock types and special, features such as nodules,
layers, faults and coatings. As seen in Figure 2, the sandstone unit at
the surface is divided due to the degree of physical and chemical weathering.
The high chroma (brown) shows where oxidation of iron has occurred. This
upper zone will be lower in sulfur due to oxidation and leaching... It is
generally, more porous and less consolidated than the underlying .low chroma
(gray) unoxidized rock. Most of the carbonates that were present in the
oxidized rock have been removed by leaching. Directly underlying the
sandstone unit is a low chroma mudrock or shale, which may or may not
contain carbonates. A layer of. black carbolithic mudrock directly over-
lies the coal. The high carbon material, indicated by a color value of 3
or less, may be high in acid-producing.sulfur.
The Pittsburgh-Redstone coal overburden, as seen in Figures 3 and -U, is high
in calcareous materials. A bed of limestone, the light gray layer, occurs
between the coal seams. This limestone is stained with yellowboy (iron
oxides) where sulfate-rich waters have been neutralized and precipitated out.
The yellowboy color varies depending on the form and amount of iron present.
The yellowboy staining can be seen on the limestone between the coal seams
in Figure 3 and also where the sulfate-rich waters are coming from the base
of the Pittsburgh coal and draining over a calcareous mudstone in Figure h.
A rock type comparison can be made between the overburden in Figure 2 which
is comprised mainly of sandstone with some mudrock or shale and the over-
burdens in Figures 3 and U which are predominantly limestones and calcareous
mudstones, mudrocks, and shales with some sandstone.
The classification of soil horizons and rock type and the determination of
color are given in the following procedures. To aid in the determiniation of
soil horizons and rock types and to predict their useful properties, methods
for rock hardness, detection of calcareous materials, and estimation of rock
and soil textures are included. Special interest features (such as presence
of pyrite, mica, gypsum, epsomite, Fe-Al sulfates and others) assist the
observer in predicting potentially favorable or unfavorable materials in
the overburden for selective placement and use during reclamation. At the
-------
Figure 2. Highwall showing high and low chroma color characteristics,
-------
Figure 3. Pittsburgh-Redstone overburden showing yellowboy staining on
the limestone between the coal seams.
10
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a^wTc. ~ ' i"
'••If
Figure 1*. Pittsburgh-Redstone overburden showing extreme yellowboy staining
on a calcareous mudstone below the Pittsburgh coal seam.
U
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end of each procedure a meaning of the clue has been included. Through
these meanings, generalized field predictions can be made or decisions can
be reached regarding the need for laboratory analyses.
2.1.2 Soil Horizons and Rock Types
2.1.2.1 Principle—
Soil horizons and rock types will react differently when exposed on the
surface or near-surface after reclamation. This procedure defines individ-
ual soil and rock units for field and/or laboratory identification.
2.1.2.2 Comments—
Both soils and rocks must be examined on a freshly exposed" surface. The
following characterizations of each soil and rock type will aid in their
identification:
1. Soil Horizon 1 is the surface layer which is usually darkened by organic
matter. It is the zone of maximum biological activity (i.e., it will have
the most plant roots; the most earthworm activity) and the zone of maximum . .
accumulation of organic matter.
2. Soil Horizon 2 lies between Horizons 1 and 3 and often is referred to
as the "subsoil". It will have some plant roots and earthworm activity,
but less than the overlying Horizon 1. Horizon 2 may contain a zone of clay
accumulation, which should be favorable in a coarse textured soil and
unfavorable in a fine textured soil.
3. Horizon 3 is a zone of weathered rock or earthy material. It is uncon-
solidated material with little or no biological activity. This horizon will
often have individual rock fragments larger than 2 mm. Horizon 3 extends
down to consolidated, intact bedrock or a depth of 1.5 m (5 ft) whichever
is shallower. Horizon 3 may contain a fragipan.
U. A fragipan is a dense, firm layer of intermediate texture that impedes
free movement of air and water down through the soil and restricts root
growth. Plant roots cannot branch out in this layer and often grow laterally
along its top. When crushed between thumb and finger, a dry piece of this
layer shatters abruptly rather than crumbling gradually. The fragipan
becomes extremely hard during the dry season and may be difficult or
impossible to penetrate with a soil tube or to crush with thumb and fore-
finger.
5. Earthy material (EM) is a broad term for any unconsolidated material
between a depth of 1.5 m (5 ft) and consolidated bedrock. It may be similar
to horizon 3 in composition and appearance.
6. Drift is a broad term for glacial deposits.
12
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7. Till is unstratified and unsorted drift deposited directly by glacial
ice. Till consists of clay, silt, sand, gravel, and boulder-size particles
of varied rock types -which can be intermixed in any proportion.
8. Outwash (OW) was deposited by melt-water streams beyond active glacial
ice. In contrast to till, outwash is stratified and sorted.
9. Loess is a homogeneous, unindurated deposit consisting predominantly
of silt-size particles, with smaller amounts of very fine sand and/or clay-
size particles. Loess may or may not be stratified.
10. Sandstone (SS) contains more than 50 percent sand-size (less than 2 mm
and greater than 0.05 mm in diameter) particles. The particles are pre-
dominantly quartz and may be cemented with silica, iron oxide, carbonates,
or clays. Qualitative modifiers such as calcareous, argillaceous, micaceous,
and pyritic, for example, are used when they seem to add useful information.
11. Mudrock (MR) is a broad term for a sedimentary rock dominated by silt-
size and/or clay-size particles. The term is used when a rock cannot be
definitely distinguised as either a mudstone or shale. Mudrock can be
further subdivided into hard mudrock (moist hardness greater than 2.5) or
normal mudrock (moist hardness less than 2.5). Mudrock may contain as much
as 50 percent sand-size particles if properties are judged to be dominated
by silt and/or clay. Mudrocks may contain any proportion of carbonates so
long as properties are dominantly silt and/or clay when rubbed in water.
12. Mudstone (MS) is a non-fissile mudrock dominated by silt-size and/or
clay-size particles. Mudstones have a moist hardness of less than 2.5.
They differ from shale because of their non-fissile nature. Mudstones may
contain as much as 50 percent sand-size particles if properties are judged
to be dominated by silt and/or clay.
13. Shale (SH) is a mudrock that appears predominantly fissile (having a
tendency to split along parallel planes into thin layers). These layers
must be less than 5 mm thick. Shales can be further subdivided into hard
shale (moist hardness greater than 2.5) and normal shales (moist hardness
less than 2.5). They differ from mudstones because of their fissile nature.
lU. Limestone (LS) is a sedimentary rock consisting dominantly of calcium
carbonate. On a freshly exposed surface, limestone will react with a
noticeable "fizz" upon application of dilute hydrochloric acid. Limestones
must have a moist hardness of greater than 2.55 thus distinguishing them
from calcareous mudstones. When powdered, the powder will have a Munsell
color value of 7 or greater. Some limestones are dolomitic due to subs+i-
tution of magnesium for some of the calcium. Dolomitic limestones (or
dolomite) will only react with cold dilute hydrochloric acid when applied
to the rock powder.
15. Chert, Flint, and Jasper are rocks consisting dominantly of amorphous
silica or extremely small (cryptocrystalline) quartz and hard (6.5 to 7.0
on Moh's scale) enough to scratch glass or an ordinary knife blade.
13
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16. Carbolith (Carb) is a name that has been coined (Smith et al., 197M
to cover dark colored sedimentary rocks that will make a black or very dark
(Munsell color value of 3 or less) streak or powder. Rocks under this name
include coal not scheduled for mining, impure waste coal, bone coal, high-
carbon shales, and high-carbon muds. In general, such rocks will contain
at least 25 percent carbonaceous matter oxidizable at 350-UOO°C.
17. Intercalate (l) is a term coined for use in this manual to describe
rocks which contain at least two different rock types that are so intimately
interlayered or "intercalated" that they cannot conveniently be sampled
separately. Intercalates have at least three or more layers within a 13 cm
(5 in) measured section. This rock type can be defined in greater detail by
listing in order of abundance some or all of the kinds of rocks included.
Commonly only two or three types of rock will be listed to suggest the
dominant properties of an Intercalate (e.g. I-SS/MS, I-SS/MR/Carb).
2.1.2.3 Chemicals'—
Hydrocholoric acid (HCl), 1 part acid to 3 parts water: Dilute 250 ml of
concentrated HCl to a volume of 1 liter with distilled water.
2.1.2.U Materials—
1. Shovel.
2. Rock hammer.
3. Soil knives (any kind of knives, nails, knitting needles, pencils, or
pointed objects can be substituted).
k. Dropper bottle (for holding the acid).
5. Wash bottle.
6. Munsell color book.
7. Record book.
8. Ruler or tape measure.
9. Hand lens, 10 power.
2.1.2.5 Procedure—
2.1.2.5.1 For Soils—These steps are used for the determination of soil
horizons.
1. Examine freshly exposed soil profile. NOTE: If a freshly exposed
profile is not available, a pit can be dug or a core taken of the profile.
If a profile does exist, it can be cleaned off with a shovel to expose a
fresh surface.
14
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2. Examine profile for the point of separation of horizons 1 and 2 (see
2.1.2.2) and mark point with a soil knife.
3. Examine profile for the point of separation of horizons 2 and 3 (see
2.1.2.2) and mark point with a soil knife.
k. Beginning at the original land surface, record depth of each horizon.
5. Record depth to bedrock or 150 cm (5 ft) whichever comes first. NOTE:
If depth to bedrock exceeds 150, cm (5 ft), record thickness of earthy
material (see 2.1.2.2).
6. Examine profile for presence of a zone of clay accumulation (see
2.1.2.2). Record depth from surface and thickness if found to exist.
T. Examine profile for presence of a fragipan (see 2.1.2.2). Record depth
from surface and thickness if found to exist.
8. Record color of each horizon (see 2.1.3).
9. Record texture of each horizon (see 2.1.8).
10. Record presence of any nodules, concretions, or any other features
deemed necessary to detail the profile.
2.1.2.5.2 For Rocks—These steps are used for the determination of rock
type.
1. Examine a fresh surface of the rock. NOTE: This can be accomplished
by breaking the rock with a rock hammer.
2. Test rock for hardness (see 2.1.U).
3. Test for presence of carbonates with 1:3 HC1 (see 2.1.5).
U. Using a knife, scrape the rock to form a powder. Determine powder color
(see 2.1.3). NOTE: The powder color can be taken of some rocks by streaking
the rock on a streak plate (unglazed porcelain plate) and determining the
color of the streak.
5. Using data obtained in steps 2-U, determine and record rock type
(see 2.1.2.2).
6. Record presence of pyrite and/or mica (see 2.1.6) as well as any other
rock features (see 2.1.T).
2.1.2.6 Meaning of Clue—
1. If horizon ,1 is 25 cm (10 in) or more in thickness having a moist color
value and chroma of 3.5 or less, it will be high in soil organic matter, can
be high in_plant nutrients, and generally have favorable properties with
respect to tillage and water relationships.
15
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2. Fragipaas make unfavorable soil material.
3. Zone of clay accumulation could be unfavorable soil material, especially
where clay content exceeds 35 percent.
U. Drift and till can contain members of any size fraction from boulders
to clay. Individual characteristics will determine their use.
5. Outwash, if mixed with suitable "fines," may have good soil potentials.
6. Loess will have a favorable soil texture and usually is calcareous.
Soils developed in loess that have been leached can be neutral to strongly
acid.
7. Sandstone can have a textural range from very coarse to loamy and can
be pervious. Proportions and porosity of coarse fragments are important
variables that depend on strength of cementation and mineralogy.
8. Mudrock can have the properties of a mudstone and/or shale. Soils
formed from mudrock will be of a medium to fine texture and, depending on
hardness, may or may not produce coarse fragments. Calcareous mudrock
should be considered for its neutralizing potential.
9. Mudstones will form soils having a medium to fine texture. In some cases,
high-alumina clays are abundant, and resulting soils have relatively high
anion-exchange but low cation-exchange capacity, even though clay percentages
are high. Minesoil management difficulties may occur with either silty or
clayey textures because of weak structures. Plant nutrient reserves may be
adequate, and carbonates may be present at any level below that of a
recognized limestone or dolomite.
10. Shales can form soils having a medium to fine texture with coarse
fragments in the form of chips derived from their fissile nature. Any
level of carbonates and plant nutrients may be present.
11. Limestones and dolomites will persist as coarse fragments, unless
broken down during mining operations. As long as limestone or dolomite
remain in coarse fragments, neutralization effects will be minimal.
12. Chert, flint, and jasper, if highly weathered, may contain consider-
able useful porosity.
13. Carboliths are a common source of pyritic sulfur. These rocks may
contain carbonates or simple or complex sulfate salts. Carboliths may be
high in phosphorus which can be used as a plant nutrient if the toxic acids
can be neutralized. Since carboliths have a color value of 3 or less, they
will absorb heat which can be detrimental in hot weather and favorable in
cold weather until well vegetated.
1^. Intercalates, by definition, are combinations of any of the above rock
types and would have the characteristics of the incorporated rock types.
16
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2.1.3 Color
2.1.3.1 Principle—
A standard color system is required for uniformity of description among
field workers. The Munsell Soil Color Charts are standards which subdivide
color into three measureable elements: hue, value and chroma.
In these color charts, hue is the dominant spectral color (red, yellow,
green, blue, and purple) and is related to wavelength of light; value is the
measure of lightness or darkness and is related to total reflected light;
and chroma indicates purity or strength of color (or departure from neutral
of the same lightness).
2.1.3.2 Comments—
The quality and intensity of light affects the visual impression of color
from the standard color chips and the sample. When using the color standards
in the field or laboratory, it is important that the quality of light be
similar to the white light of mid-day and the amount of light be adequate
to visually distinguish between the color chips. Color measurements made
in the field during early morning or late evening and during a hazy
overcast day will not be precise.
Color values are usually lower when samples are moistened as compared to
air-dry. Color measurements are made on air-dry, powdered (less than 60
mesh) samples in the laboratory and on a freshly exposed surface in the
field.
2.1.3.3 Chemicals—
None required.
2.1.3.U Materials—
1. Munsell Soil Color Charts (available from Munsell Color Division,
Killmorgan Corporation, Baltimore, Maryland 21218).
2. Spatula.
2.1.3.5 Procedure—
NOTE: If powdered (less than 60 mesh) sample is used instead of soil ped
or rock fragments, place 0.5 g of sample on the tip of a spatula and omit
steps 1 and 2.
1. Break soil ped or rock fragment in half.
2. Use a freshly exposed surface to determine color. NOTE: In the case
of more than one color being present, select the dominant color for color
determination. Record the secondary color(s) as "mottles."
17
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3. Compare the sample to the 10YR chips. NOTE: If the sample is judged
to be more red, compare sample to chips with a more red hue. If the sample
is judged to be more yellow, compare sample to chips with a more yellow hue.
If the sample is judged to have a chroma less than 1, compare sample to
neutral chips.
It. After selecting the proper hue, match the sample to the chip to which
it most closely corresponds.
5. Record the hue, value and chroma. NOTE: The color hue is the number
found in the top right corner of the color page, the value is the number to
the left of the row in which the color chip was selected, and the chroma
is the number at the bottom of the color chip column. Color is recorded
as hue then value then chroma (e.g. 10YR 6/U).
2.1.3.6 Meaning of Clue—
In rock material, hue can be used in a very general way as a clue to indicate
rock quality. A striking example of a favorable minesoil material having a
readily distinguished color hue and chroma is the dusky red shales and
mudstones common in western and northwestern West Virginia.
Value can be used to readily distinguish highly carbonaceous black shales
from true gray shales that appear black to the casual observer. Bonecoal,
roof shales, and other dark or black appearing rocks frequently contain
significant amounts of pyrite and may be a source of extreme sulfuric acid
acidity unless neutralizers are present. The field clue to such material is
a black (value of 3 or less on any Munsell hue) streak when rubbed on an
unglazed porcelain plate or hard white rock such as chert or when the rock
is powdered by scraping with a knife. Dark colored clay or silty shales
that are low in carbon, on the other hand, are medium or light gray (Munsell
color value of k or higher) when powdered.
Chroma is one of the most easily recognized color attributes, and can be
used to recognize many soil and rock features. It is now well established
that minesoil developing in overburden from the intensely weathered zone
below the original land surface is safe from pyritic sulfur (pyrite,
marcasite, and chalcopyrite) and extreme acidity. This zone commonly is
6 m (20 ft) deep or deeper in West Virginia, depending on lithology, degree
of structural fracturing of the rock, and position of the water table.
Brown and yellow rock colors (chroma 3 or higher on Munsell Soil Color
Charts) as typified by materials from the weathered zone, provide useful
clues to safe materials regardless of their position in the stratigraphic
section. However, absence of high chromas in near-surface soils and rocks
can result from intense leaching of iron oxides or (in soils) from impeded
drainage which causes iron reduction. The low chroma imparted to the
surface of highly leached materials in soils and near-surface rocks can be
distinguished readily from low-chroma rocks below depth of iron oxidation.
Low chromas (gray colors) caused by leaching or impeded soil drainage occur
on rock or soil ped exteriors. In contrast, low chromas occur on the
interiors of unoxidized sandstones or shales. Color chroma has proven
reliable as a field clue particularly with many sandstones. Freshly broken
18
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rock surfaces with chromas of 3 or higher (hand specimen or pulverized
sample) indicate negligible percentages of pyritic sulfur. Chromas of 2
or less often correspond with sufficient pyrite to cause pH below U.O and
biotoxic reactions unless neutralizers are abundant.
Darker color values of undisturbed surface soils commonly indicate high
organic matter content. A moist soil value and chroma of less than 3.5
indicates a mollic, umbric, or anthropic surface horizon.
2.1.U Determination of Rock Hardness
2.I.U.I Principle—
Hardness is the resistance of a mineral or rock to scratching. The
numerical value for hardness is based on Moh's hardness scale. Moh
derived a scale where the softest mineral, talc, is number 1 and the
hardest mineral, diamond, is number 10. All minerals (and rocks) fall
within this range of 1 to 10 depending on hardness.
2.1.U.2 Comments—
Three ranges of hardness (less than 2.5; 2.5 to 5; greater than 5) based on
Moh's scale are used in this procedure. These ranges are determined in the
field by using the hardness of the fingernail as 2.5 and the steel of a
pocket knife as a little over 5.
Care must be taken to insure that a powder, and not the breaking off of
individual grains, is being formed when a hardness "standard" (fingernail
or steel knife) is scratched against the rock fragment. This is especially
true with sandstones. ROTE: Care must be taken to insure that the "standard"
is not scraping off on to the rock. A visible groove should be evident in
the rock surface if it is scratched.
2.1.1*. 3 Chemicals—
None required.
2.1.U.U Materials—
Steel knife.
2.1.U.5 Procedure—
1. With the steel knife try to scratch the rock fragment. If no scratch
occurs, record hardness as greater than 5. If a scratch occurs, continue
to step 2.
2. With a fingernail try to scratch the rock fragment. If no scratch
occurs, record hardness as 2.5 to 5- If a scratch occurs, record hardness
as less than 2.5.
19
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2.1.^.6 Meaning of Clue—
As a general rule: the harder a rock; the better it will withstand
weathering and form coarse fragments.
2.1.3 Presence of Calcareous Material
2.1.5.1 Principle—
Calcium carbonate is the major constituent in limestone; however, soils and
other rock types can also contain calcium carbonate. The addition of cold
dilute hydrochloric acid to a sample containing calcium carbonate causes
the following reactions to occur:
Calcium carbonate + hydrochloric acid forms calcium chloride + carbonic acid
CaC03 + 2HC1 = CaCl2 + H2C03
Carbonic acid will further disassociate to water + carbon dioxide
H2C03 = H20 + C02
Since carbon dioxide gas is released, a noticeable effervescence (bubbling)
and even an audible "fizz" occurs indicating the presence of carbonates.
2.1.5*2 Comments—
The particle size of the material is reduced by scraping the rock fragment
with a knife or other tool to form a powder allowing more surface area to
become available for reaction with the acid. Calcareous material, which
may not have been detected previously, may now be detected.
Care must be taken to insure that the acid is reacting with the rock or soil
and not with a calcium carbonate coating.
2.1.5.3 Chemicals—
Hydrochloric acid (HCl), 1 part acid to 3 parts water: Dilute 250 ml of
concentrated HCl to a volume of 1 liter with distilled water.
.2.1.5.U Materials—
1. Dropper bottle.
2. Knife.
2.1.5«5 Procedure—
1. Add one or two drops of cold hydrochloric acid to a fresh surface of
the sample. NOTE: Presence of calcium carbonate (CaCOo) is indicated by
a bubbling reaction or audible "fizz."
20
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2. If no reaction occurs, scrape the surface with a knife or other tool to
produce a powder.
3. Add a drop of cold hydrochloric acid to the powder and check for
presence of carbonates as stated in step 1.
2.1.5.6 Meaning of Clue—
Our results indicate that at least 20 tons CaCOo equivalent per 1000 tons
of material is present if a noticeable reaction occurs.
2.1.6 Determining Rock Texture and Presence of Pyritic and Micaceous
Material Using Ten Power Hand Lens
2.1.6.1 Principle—
Pyrite and mica are common minerals in sedimentary rocks. Using a ten power
hand lens for magnification, the presence of small pyrite grains, mica
flakes, or inclusions may be detected or confirmed. Individual mineral
grains may be seen for texture observations.
2.1.6.2 Comments—
Pyrite is commonly found in crystal clusters with many faces. It has a
metallic look and is usually pale brass-yellow. However, it may appear to
be black due to weathering or to extremely small particle size.
Mica may range in color from pale golden brown to black. It usually appears
as flakes in a rock, sometimes along bedding planes. Pyrite can be distin-
guished from mica, since pyrite is opaque and will glisten on all surfaces
of the crystal whereas mica will only glisten on one surface as the sample
is tilted.
Individual mineral grains in the size range of coarse silt or coarser can
be detected.
2.1.6.3 Chemicals'—
None required.
2.1.6.H Materials—
1. Hand lens, ten power.
2. Hammer.
2.1.6.5 Procedure—
1. View surface of sample with ten power hand lens.
2. Examine for presence of pyrite or mica (see 2.1.6.2).
21
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3. Examine texture of sample to detect individual mineral grains in the
size range of coarse silt or coarser.
U. Break the rock with a hammer to expose a fresh surface. Repeat steps
2 and 3.
2.1.6.6 Meaning of Clue—
Since pyrite may weather to sulfuric acid, rocks containing pyrite may
indicate zones of potentially toxic materials in the overburdens. Laboratory
analyses would "be needed to verify this implication.
Micas affect the weathering potential of a rock. Rocks high in mica
(especially if the mica is in layers within the rock) usually tend to
weather rapidly.
Texture is important in sampling and identifying rock types, especially in
classifying sandstones by texture.
2.1.7 Other Soil and Rock Features
2.1.7.1 Principle—
More detail can be added to the overburden material description by noting the
taste, smell, and presence of lenses, minerals, fossils, concretions and
nodules. Taste and smell can indicate the presence of Fe-Al sulfates and
epsomite or gypsum. Lenses, which can be between rock types or within a
rock type, show a change in mineralogy. By looking at concretions, nodules,
and plant and animal fossils, zones of carbon or calcareous material may
be detected.
If any of these features exist in an overburden, their presence should
be recorded.
2.1.7.2 Comments—
Laboratory procedures may be required to determine the presence of gypsum,
epsomite, the Fe-Al sulfates, as well as the mineralogy of the concretions
and nodules. Lenses, which are not detected in the field,'may be found
to exist after drawing the stratigraphic cross-sections (see 1.3.2) of the
area.
Definitions of terms used in this procedure can be found in the glossary.
2.1.7.3 Chemicals—
None required.
2.1.1.k Materials—
None required.
22
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2.1.7.5 Procedure—
1. Taste and smell - The presence of simple or complex Fe-Al sulfates
(usually white, gray or reddish in color) can be detected by its metallic
taste and smell. The smell is similar to that of a brass door knob.
Epsomite (colorless to white, but may vary due to impurities) can be
detected by its bitter, non-metallic taste.
2. Lenses - Lenses may occur between or within soil and rock types. Both
lateral and vertical extent should be determined and recorded.
3. Minerals - Record the presence of minerals or crystals of minerals and
their composition, especially gypsum (which is colorless to white, but may
vary due to impurities, and can be scratched with a fingernail) and pyrite
(see 2.1.6).
k. The presence of both plant and animal fossils and their mineral compo-
sition should be recorded.
5. Concretions and nodules - Concretions and nodules may occur within both
soils and rock types. Determine and record their mineralogy, frequency of
occurrence, and size.
\
2.1.7.6 Meaning of Clue—
1. Fe-Al sulfates, epsomite, and gypsum - Fe-Al sulfates are extremely
acid. Epsomite and gypsum are neutral. Epsomite provides magnesium for
plant growth. Neutralization potential (see 3.2.3) and non-HCl extractable
sulfur (see 3.2.U) data should be used to determine acid producing material.
2. Lenses - Lenses show a change in soil or rock characteristics which
could change the net acid-base account of a mine site. (
3. Fossils - A potential carbonate and/or pyrite source may be detected
in animal fossils. A potential carbon and/or pyrite source may be detected
in plant fossils.
k. Concretions and nodules - A change in the net acid-base account may
occur depending on the mineralogy of the concretions and nodules.
2.1.8 Soil and Minesoil Texture by Feel
2.1.8.1 Principle--
Soil texture refers to the percentages of sand, silt and clay present in a
sample or layer of soil. All textures can be designated as belonging to
one of three families: the clayey family (includes clay loams), the loamy
family (includes silt loam), and sandy family.
23
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2.1.8.2 Comments (adapted from USDA, 1975)--
Sand particles feel gritty when rubbed between the fingers and are not
sticky or plastic when wet. Silt particles feel smooth and powdery much
like flour when rubbed between the fingers and are only slightly plastic
or sticky when moist. Clay particles feel smooth and are sticky and plastic
when moist.
A sample of the clayey family will have 35 percent or more clay content with
the remaining fraction composed of silt and sand. The feel may be smooth
or slightly gritty depending on the relative proportions of sand and silt
present. The moist sample will feel plastic or stiff and sticky, and form
a long flexible ribbon that is durable when handled, especially when the
clay content exceeds hO percent. If allowed to dry, the sample will form
hard clods that are difficult to break apart with the fingers, especially
with higher clay contents.
A sample of the loamy family will contain less then 35 percent clay and
less than 15 percent fine sand or coarser. The moist sample may or may not
be sticky and plastic or form a ribbon that breaks easily depending on
silt content. The feel will be somewhat gritty if the sand fraction
dominates and smooth (flourly) if silt dominates. Firm clods that can
readily be crushed with the fingers will form upon drying.
In areas where soils are high in silt, the loamy family can be subdivided
into a silty family and loamy family. The silty family will contain less
than 15 percent sand and greater than 65 percent silt with the remaining
material being clay. A moist sample will feel smooth when kneaded and
will not feel gritty nor form a very good ribbon.
A sample of the sandy family will contain sands and loamy sands, exclusive
of loamy very fine sand and very fine sand textures. When the moist sample
is rubbed between the fingers, it will feel abrasive and no ribbon will be
formed.
The adjectives skeletal or fragmental can be added to the above textural
families. If particles having an equivalent diameter coarser than 2 mm
make up at least 35, percent by volume of the layer being studied and contain
enough fine earth to fill the larger than 1 mm interstices, the term skeletal
is used. Soils dominated by stones, cobbles, gravel, and very coarse sand
particles with not enough fine earth to fill the larger than 1 mm inter-
stices are termed fragmental.
Texture by feel can be confirmed by laboratory analysis, either by the
hydrometer method or the pipette method. See sections 3.U.2 and 3.U.3 for
discussion of these procedures.
2.1.8.3 Chemicals—
Water (H20).
24
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2.1.8.U Materials—
Wash bottle.
2.1.8.5 Procedure—
1. Take about a teaspoon of soil in the palm of the hand.
2. Add water slowly from the wash bottle, constantly kneading the soil.
Knead to the consistency of a moist workable putty. NOTE: Working the
soil to the proper consistency is critical since moist soil feels different
to the fingers than dry soil.
3. When the soil is at the proper consistency, rub it between the thumb
and fingers. Try to press the soil into a thin ribbon.
U. Determine the soil or minesoil texture using section 2.1.8.2.
2.1.8.6 Meaning of Clue—
By taking soil and minesoil textures, the relation of particle sizes with
each other can be determined. If a sample is high in clay, compaction
problems can exist. Samples high in sand content can be a problem during
periods of extensive drought due to low water holding capacities. Samples
high in silt are more favorable.
2.2 OVERBURDEN SAMPLING AND LABELING
2.2.1 Summary
Before useful laboratory analyses can be performed, consistent sampling and
labeling procedures must be utilized. Exploration cores can provide
excellent samples. Since rock cores remain intact, accurate rock type
depths from the surface, and thicknesses can be measured. Any vertical
variation within a rock unit can be seen and noted.
If exploration cores are not available, samples at 30 cm (12 in) increments
can be obtained using a blast hole drilling rig. The rock chips blown
from the drill are collected on a shovel. Exact rock type, depths from the
surface, and some vertical variations within rock units are lost.
Hand samples can be taken from a freshly exposed high wall if neither
exploration cores nor blast hole drillings are available. Accurate depths
from the surface and variations in rock units can be determined; however,
the procedure of working vertical faces with ropes and ladders may be time
consuming.
Materials of special interest can also be selectively sampled. Selective
samples, as the term implies, are taken by hand. They are especially useful
-------
for checking variation within rocks that appear similar and for determining
properties of peculiar or extreme specimens.
Once a sample is collected, it must be properly labeled to include all data
about the site. Information such as site location, depth taken, rock type,
and date sampled are necessary, not only to keep from confusing samples,
but to locate sampled areas if the need should arise.
Since variations can exist within an overburden, the laboratory data can
only reflect what exists within that particular exploration core, blast
hole, hand sampled high wall column, or selective sample. The more infor-
mation acquired about a site, the better an overall picture can be made of
the overburden material.
2.2.2 Rock Chip Sampling From Blast Hole Operations
2.2.2.1 Principle—
Rotary drilling gives a vertical column of the overburden material. The
drilling breaks the material into rock chips and compressed air brings the
chips to the surface.
2.2.2.2 Comments-—
Samples should be taken where overburden material is the thickest, e.g. top
of a hill or farthest strip cut into a slope, to obtain the most information.
The lateral distance and direction between sampled blast holes should be
recorded where more than one column of rock chip samples is collected on a
job. Indication of upslope or downslope from a previous sample should be
recorded.
The geographical location of the sample site should be located on a U.S.G.S.
7 1/2 minute topographic map. Latitude and longitude coordinates are
determined to four decimal places by using a ruler.
Blast hole drilling offers a speedy and easy method of collecting rock chip
samples. Exact depth of a rock type break is lost, but relative depths can
be obtained.
This procedure will not work with some center-platform types of drills.
Samples from the drill bench to the surface must be taken by hand sampling
(see 2.2.3.1) for a complete vertical column of the overburden material.
2.2.2.3 Chemicals—
None required.
2.2.2.k Materials—
1. Long handled shovel (common round pointed garden shovel is adequate).
26
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2. Container with lid, round, one pint or one quart. NOTE: -One container
for each foot drilled or each sample obtained is required.
3. Felt-tip pen or other marker for legibly labeling sample container.
k. Wooden crate or heavy corrugated paper carton to transport rock filled
containers.
5. Drill rig, rotary bit, compressed air type (Bobbins Rotary Drill Model
RR-T or similar type).
6. Record book.
2.2.2.3 Procedure (revis.ed and updated from Smith et al., 197*0—
1. Determine the number of links per foot of the drive mechanism suspension
chain on the drill rig.
2. Depth increment is approximated by marking successive link pins that
occur about 30 cm (12 in) apart. Use a dab of grease or other mark that
will be visible through the dust. NOTE: Every sixth pin is 3^ cm (13.5 in)
on the commonly used Robbins drill rig. This is close enough to the sug-
gested 30 cm depth increment, but total depths recorded should count the full
3k cm in each successive increment.
3. Begin sampling with the first 30 cm (12 in) increment drilled from the
leveled bench on which the rig is parked.
k. Hold shovel under dust apron almost touching the rotary drill extension.
Air-expelled rock chips are allowed to collect on the shovel as the bit
lowers 30 cm (6 link pins). NOTE: If an obvious change in rock type occurs
within the 30 cm (12 in) interval, the rock types should be sampled sepa-
rately and depth of change recorded.
5- Place shovel-full of sample in a container. Discard .any material over-
flowing the container.
6. Samples are marked for each depth increment in the order 1, 2, 3, etc.,
collected from the surface downward.
7. Containers are marked occasionally with the location's abbreviation to
aid in organization.
8. Place filled containers in a crate or heavy carton. Include a page
of accompanying field notes which contain location, surface elevation,
total depth drilled, unusual drilling conditions encountered, changes in
rock type (see 2.1.2), depth encountered, depth of drill bench with respect
to original land surface, thickness of coal seam(s) scheduled for mining,
and date sampled. Transport to laboratory.
27
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2.2.3 Sampling From Exploration Cores
2.2.3.1 Principle—
Exploration cores give a vertical column of overburden material. The cores,
usually 5 cm (2 in) in diameter, leave intact rock samples. From these cores
detailed geologic logging can be accomplished.
2.2.3.2 Comments—
Cores are logged and sampled from the top to the bottom of the core. Hand
samples from the drill bench to the surface must be taken by hand if an
intact soil core was not obtained.
The geographical location of the core should be located on a U.S.G.S 7 1/2
minute topographic map. Latitude and longitude coordinates are determined
to four decimal places using a ruler.
Sample intervals cited are a general rule to follow. Special characteristics
of the core will ultimately determine sample interval and number of samples
required.
2.2.3.3 Chemicals.—
Hydrochloric acid (HCl), 1 part acid to 3 parts water: Dilute 250 ml of
concentrated HCl to 1 liter with distilled water.
2.2.3.1* Materials.—
1. Rock hammer.
2. Containers with lids, one-quart. NOTE: One-pint containers may be
substituted for smaller samples.
3. Felt-tip pen or other marker for legibly labeling sample containers.
U. Crate or heavy corrugated carton for transporting containers to
laboratory.
5. Record book.
6. Hand lens, 10 power.
7. Dropper bottle for acid.
2.2.3.5 Procedure (revised and updated .from Smith et al., 19TU)—
1. Record the following: (a) site location, (b) depth from land surface
to top of core, (c) total length of core, (d) elevation of land surface,
(e) coal seams scheduled for mining with elevations and thickness, and
(f) date sampled.
28
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2. Samples 12 cm (5 in) long are taken from near the center of the
represented sample interval.
3. Locate coal seams scheduled for mining.
h. Take a sample representing the total 30 cm (12 in) of material
overlying a coal seam scheduled for mining.
5. Take a sample representing the total 30 cm (12 in) of material under-
lying a coal seam scheduled for mining. NOTE: Samples are not taken of
the coal seam scheduled for mining.
6. Determine soil horizons and rock types (see 2.1.2). NOTE: In cores,
if the soil horizons are absent, a pit will have to be dug to obtain soil
horizon information (see 2.2.4).
7. Take samples. NOTE: Samples are taken from near the center of the
represented sample interval. The sample interval is usually 30 cm (12 in)
unless one of the following criteria can be met:
a. Rock members less than 13 cm (5 in) thick are considered transition
zones, with the upper half incorporated with the overlying rock member
and the lower half incorporated with the underlying rock member. Existence
of transition zones should be recorded.
b. When an obvious change in chroma or texture (e.g. high (greater than 3)
versus low (less than 2) chroma or coarse versus fine grained sandstone)
occurs within a rock type, the two zones are sampled separately.
c. Zones of special interest should be sampled separately regardless of
thickness.
d. If a sandstone is determined by an experienced person to have the same
characteristics throughout, one sample can represent up to 1.5 meters (5 ft)
of a thick-bedded or highly weathered (chroma 3 or higher) sandstone.
e. If the rock type has the same characteristics throughout, as determined
by an experienced person, one sample can represent up to 1 meter (3 ft) of
carbolith, mudrock, mudstone, shale, limestone, or other rock type.
8. Record sample number, soil horizon or rock type, and sample interval
represented by the sample.
9. Record any items of special interest contained in the sample.
10. Place sample in container and label (see 2.2.6).
11. In the laboratory, recheck .soil horizons and rock types. Determine
soil horizon and rock type color. CAUTION: Above all, use intelligence
guided by experience when sampling.
29
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2.2.1* Hand Sampling A Highwall
2.2.11.1 Principle—
A vertical column of samples is needed to represent the different materials
contained in the overburden of a coal seam. Samples are taken with a rock
hammer from freshly exposed surfaces of the material.
2.2.^.2 Comments—
This procedure should be used only when an exploration core or a blast hole
drill is not available or when mining operations expose different strata
from those represented by earlier investigations.
Samples must be taken of freshly exposed surfaces. Contact with weathering
elements over a long period of time will change the characteristics of
exposed surfaces. Samples are taken by hand sampling the highwall at
prescribed intervals from the coal to the land surface. One should work
along access roads, use an extension ladder, or ropes and cliff climbing
techniques to acquire samples. When working near a highwall, remember the
presence of loose rock and use care. Hard hats, steel-toed shoes, and other
safety equipment are necessities.
If the vertical column of overburden material is inaccessible or incomplete,
one can sample the total column by combining lateral movement with vertical
sampling, thus establishing a step-like sampling pattern across the highwall.
The geographical location of the sample site should be located on a U.S.G.S.
7 1/2 minute topographic map. Latitude and longitude coordinates are
determined to four decimal places by using a ruler.
Sample intervals cited are a general rule to follow. Special characteristics
of the highwall will ultimately determine sample interval and number of
samples required.
2.2.U.3 Chemicals—
Hydrochloric acid (HCl), 1 part acid to 3 parts water: Dilute 250 ml
of concentrated HCl to a volume of 1 liter with distilled water.
2.2.h.k Materials—
1. Rock hammer and chisel.
2. Extension ladder (if required).
3. Climbing gear (if required).
h. Containers with lids, one-quart capacity, plastic coated cardboard.
NOTE: One-pint containers may be substituted depending on sample size.
5. Felt-tip pen or other marker for legibly labeling sample containers.
30
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6. Crate or heavy corrugated carton.
7. Record book.
8. Hand lens, 10 power.
9. Dropper bottle for acid.
2.2.U.5 Procedure—
1. Record the following: (a) site location, (b) coal seams scheduled
for mining with elevations and thicknesses, (c) elevation of original
land surface, and (d) date sampled.
2. Samples are taken from near the center of a freshly exposed surface
of the sampling interval.
3. Locate coal seams scheduled for mining.
U. Take a sample representing the total 30 cm (12 in) of material overlying
a coal seam scheduled for mining.
5. Take a sample representing the total 30 cm (12 in) of material under-
lying a coal seam scheduled for mining. NOTE: Samples are not taken of
the coal seam scheduled for mining.
6. Determine soil horizons and rock types (see 2.1.2).
T. Take samples. NOTE: Samples are taken from near the center of the
represented sample interval. The sample interval is usually 30 cm (12 in)
unless one of the following criteria can be met:
a. Rock members less than 13 cm (5 in) thick are considered transition
zones, with the upper half incorporated with the overlying rock member
and the lower half incorporated with the underlying rock member. Existence
of transition zones should be recorded.
b. When an obvious change in chroma or texture (e.g. high (greater than 3)
versus low (less than 2) chroma or coarse versus fine grained sandstone)
occurs within rock type, the two zones are sampled separately.
c. Zones of special interest should be sampled separately regardless of
thickness.
d. If a sandstone is determined by an experienced person to have the same
characteristics throughout, one sample can represent up to 1.5 meters
(5 ft) of a thick bedded or highly weathered (chroma 3 or higher) sandstone.
e. If the rock type has the same characteristics throughout, as determined
by an experienced person, one sample can represent up to 1 meter (3 ft) of
carbolith, mudrock, mudstone, shale, limestone, or other rock type.
31
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8. For each sample record sample number, soil horizon or rock type, and
thickness of material represented by the sample.
9. Record any items of special interest contained in the sample.
10. Place sample in container and label (see 2,2.6).
11. Recalculate depth so that soil horizons and rock types are recorded
as depth from land surface.
12. In the laboratory, recheck soil horizons and rock types. Determine
soil horizon and rock type color. CAUTION: Above all, use intelligence
guided by experience when sampling.
2.2.5 Selective Samples
2.2.5.1 Principle—
Selective samples are taken by hand. They are usually selected from a
sampling site on materials of special interest (such as a high pyrite
zone, vegetated versus unvegetated area, etc.). These areas of special
interest are taken into account in the total site overburden interpretation.
2.2.5.2 Comments—
The type and amount of selective samples acquired depends upon the analyses
being performed. Description and sample size varies with the individual
sampler and his specific needs or interest.
2.2.5.3 Chemicals—
None required.
2.2.5.1* Materials —
1. Rock hammer.
2. Shovel.
3. Containers with lids, one-quart capacity. NOTE: One-pint containers
may be substituted for smaller samples.
k. Felt-tip pen or other marker for legibly labeling sample containers.
5. Record book.
2.2.5.5 Procedure—
1. Use the rock hammer or shovel to acquire sample.
2. Place sample in one-quart container and cover.
32
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3. Label sample (see 2.2.6).
U. Record sample number, site location, surface elevation, date sampled,
and reasons for taking sample in the record book.
5. Transport samples to laboratory for analysis.
2.2.6 Labeling Samples
2.2.6.1 Principle—
Samples are labeled to separate one location from another or one sample from
another. Four main items are required on each sample label: site location,
sample number, depth from original land surface or sample increment, and
date sampled.
2.2.6.2 Comments—
Complete information about the site location is necessary. Site location
should include mine name (also pit number where available), sample column
number (e.g. if more than one column is sampled from the same site) or
exploration core number, longitude and latitude, surface elevation, date
sampled, and any additional information necessary to locate the sample site.
Sample numbers should be in consecutive order from the top to the bottom
of the column. Any samples taken between existing samples should be
followed by a letter in alphabetical order or a decimal point and number
in numerical order. EXAMPLE: Four samples taken between sample 2 and 3
would be 2A, 2B, 2C, 2D or 2.1, 2.2, 2.3, 2.U.
Depth should be recorded from the original land surface. When original
land surface cannot be determined, sample increments (e.g. 30 cm (l ft),
length of rock hammer, etc. ) should be recorded. Any change in sample
increments should also be recorded.
Any special interest information (such as noticeable gypsum, pyritic zone,
etc.) can be added.
2.2.6.3 Chemicals—
None required.
2.2.6.*+ Materials —
1. Shovel and/or rock hammer for acquiring samples.
2. Containers with lids, one-quart for holding samples. NOTE: One-pint
containers may be substituted depending on sample size.
3. Felt-tip pen or other marker for legibly labeling sample containers.
k. Record book.
33
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2.2.6.5 Procedure—•
1. Acquire sample using the sampling procedures (2.2.2, 2.2.3, 2.2.U, or
2.2.5).
2. Place sample in container.'
3. Label container with site location, sample number, sample depth or
sampling increment, and date sampled.
U. Record data in step 3 in record book if not previously completed during
sampling.
2.3 DESCRIBING AND SAMPLING MINESOILS
2.3.1 Describing Minesoil Profiles
2.3.1.1 Principle--
In the new classification system, Soil Taxonomy (USDA, 1975), soils are
classified on the basis of characteristics which can be observed or measured
in the field and in the laboratory. Such a study requires a vertical cross-
section extending from the surface down through 100 cm (1*0 in) below the
surface. Properties of minesoils that often are lacking or different in
undisturbed soils include the following:
1. Disordered coarse fragments. If coarse fragments constitute at least
10$ of the volume of the control section, they are disordered such that
more than 50$ will have their long axis at an angle of at least 1.0% relative
to any plane in the profile.
2. Color mottling without regard to depth or spacing in the profile. The
mottling involves color differences of at least 2 color chips in the standard
Munsell Color Charts. This mottling occurs among fines as well as within
coarse fragments or between fines and coarse fragments.
3. Splintery edges on fissile coarse fragments. If coarse fragments are
fissile, the edges are frayed or splintery rather than smooth.
k. Bridging voids. Coarse fragments bridging across voids as a result of
placement of materials leave discontinuous irregular pores. These pores
are larger than those from textural porosity.
5. Thin surface horizon higher in fines. A thin "near-surface horizon"
often immediately below a surface pavement of coarse fragments, contains
a higher percentage of fines (material less than 2 mm in effective diameter)
than any other horizon in the profile to the bottom of the control section.
6. Local pockets of dissimilar material. Local pockets of dissimilar
materials, excluding single coarse fragments, may range from 7.6 to 100 cm
34
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in horizontal diameter. These pockets have no lateral continuity and are the
result of the original placement of material and not of post-depositional
processes.
T. Artifacts. Artifacts (plastics, glass, paper, metal, tires, logs, etc.)
may appear in the profile.
8. Carbolithic coarse fragments. Carbolithic coarse fragments are frequently
found in non-carbolithic classes of minesoils. These coarse fragments,
which are usually associated with a coal horizon, are found in the profile
because of moving and mixing of overburden materials.
9. Irregular distribution of oxidizable organic carbon. The irregular
distribution of oxidizable carbon with depth in the profile is due to
the mixing of overburden materials. Both recent and geologically old
carbon compounds are involved.
2.3.1.2 Comments—
It is necessary to sample and describe fresh exposures in soils. Many
minesoils present a problem because of a high proportion of coarse fragments.
This causes hand digging to be difficult and time consuming. In some
cases profile descriptions can be taken from road cuts, gullies, slips, etc.
if the exposed surface is scraped or cleaned to remove effects of surface
weathering or overwash.
¥alk over the area, examining the surface and selecting a site representative
of the area in general. Once a site has been selected, an excavation should
be made to a depth of at least 100 cm and preferably deeper. The profile
should be described to the 100 cm depth. An experienced soil scientist
would probably prefer to describe the profile in more detail than will be
put in this method. He can do this by following the profile description
outlined in the Soil Survey Manual (USDA, 1951, p. 137-lUl). However, in
addition to the information as outlined in the Soil Survey Manual, the
properties of Spolents as described in 2.3.1.1 should be noted and recorded.
The following list of morphological features should be noted when describing
a minesoil profile:
1. Layers. Minesoils may have different layers which result from placement
of materials.
2. Depth. Depth is given in centimeters and is measured from the surface
downward (e.g. 0-10 cm).
3. Color of the matrix. See procedure 2.1.3.
k. Mottling. Describe abundance, contrast, size, and color. Since
mottling is one of the dominant properties of minesoils, extra care should
be taken in describing the mottled patterns. See procedure 2.1.3 for color
determination of the mottling.
35
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5. Texture. See procedure 2.1.8.
6. Reaction (pH). If possible, pH should "be determined in the field with a
pH meter (see procedure 3.2.2). The reaction classes of Spolents are as
follows: (a) extremely acid, pH is ij.O or less, except for carbolithic
classes (high-carbon mine waste) which are extremely acid at pH 3.0 or
lower; (b) acid, pH is h.O to 5-5, except for carbolithic classes which
have an acid range from pH 3.0 to 5.5; (c) neutral, pH is 5-5 to 8.0;
(d) alkaline, pH is greater than 8.0.
7. Coarse fragments. Total percent by volume of each layer should be
estimated in increments of 5% and recorded. Also record percent of each
type of coarse fragment, such as shale, sandstone, mudstone, etc. NOTE:
It may become necessary to break open the coarse fragments when in doubt.
8. Roots. Record the amount of roots in each layer.
9. Bridging voids. Abundance and size distribution for each layer should
be recorded.
10. Artifacts. Record the amount and depth of all artifacts found in the
profile. These artifacts can also include buried tree stumps and branches.
11. Pockets. Any pockets of dissimilar material should be described by
size, texture, color, and percent abundance.
Anything else that may seem significant or will provide additional informa-
tion about the profile should be recorded in the field notebook. Some of the
miscellaneous things that would be noted are: coatings on coarse fragments,
earthworm channels and excretions, concretions, etc.
2.3.1.3 Chemicals—
1. Hydrochloric acid (HCl), 1 part acid to 3 parts water: Dilute 250 ml
of concentrated HCl to a volume of 1 liter with distilled water.
2. Water (H20).
2.3.1A Materials—
1. Spud bar.
2. Long handled shovel.
3. Marking knives.
4. Diapers or cloth towel.
5. Field notebook.
6. Portable pH meter or pH kit.
36
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7. Munsell Soil Color Charts.
8. Tile spade.
9. Plastic sample bags, 20 pound capacity.
10. Felt-tip pen or other marker for legibly labeling sample bags.
2.3.1.5 Procedure—
1. Select the area on the minesoil to be described. Record location,
surface elevation, and description of area where pit is to be dug in the
field notebook.
2. Dig a pit vertically downward from the surface through a depth of at
least 100 cm.
3. After the pit has been dug, clean the loose material from the face of
the pit with a knife.
k. Study the features of the freshly exposed face of the pit.
5. Put a marking knife at the bottom of layer one. NOTE: This is the
surface layer which will be higher in fines than the rest of the profile.
6. After layer one has been marked, study the rest of the exposed profile
to see if any noticeable changes in material occur (e.g. a layer of
carbolithic material sandwiched between layers of high chroma sandstone).
In other words, there must be something which visually separates the
material below layer one into different layers.
1. If there are no visual differences in the material from the bottom of
layer one to the 100 cm depth, then place a knife at 25 cm intervals from
the knife that marks the bottom of layer one.
8. Number the layers going downward: 1, 2, 3, etc.
9. Describe all the properties that have been put forth in 2.3.1.1 and
2.3.1.2 for each layer.
10. Record all descriptive material for each layer in the field notebook.
11. Sample each layer of the profile according to procedure 2.3.2.
12. Label all samples as to layer number, area, location (longitude,
latitude, surface elevation), and transport back to laboratory (see 2.2.6).
2.3.2 Sampling Minesoils for Classification and Fertility
2.3.2.1 Principle—
An important source of error when investigating a soil body is taking
37
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samples for detailed laboratory measurements. Laboratory analyses only
measure parameters that are contained in a particular soil sample. If the
soil sample is taken haphazardly and is not representative of the soil body
from which it was taken, then laboratory measurements are meaningless.
Sampling of minesoils should be done for a particular purpose. In minesoils
(very young soils in pedogenic development) a measure of the variability
within the soil body is extremely useful. Therefore, subdivisions of the
minesoil, based on visual differences, are sampled and analyzed.
2.3.2.2 Comment s—•
The size of the sample depends on the purposes for sampling. For example,
several small samples should be taken if only pH is to be measured. On the
other hand, large samples are needed for doing all the measurements in
section 3.
It is extremely important to label all samples correctly. Also, all sample
numbers and descriptive information for each sample should be recorded in
the record book along with a sketched map of the minesoil showing sampling
subdivisions.
2.3.2.3 Chemicals--
None required.
2.3.2.1+ Materials—
1. Record book.
2. Felt-tip pen or other marker for legibly labeling sample bags.
3. Spud bar.
k. Long handled shovel.
5. Tile spade.
6. Paddy shovel (D-handled dirt shovel).
7. Plastic bags, 20 Ib capacity.
v
8. Plastic bags, sandwich size.
/
9. Rock hammer, flat nosed.
10. Knife, or large spatula.
11. Sieve, 7-6 cm (3 in) openings.
38
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2.3.2.5 Procedure—
1. Walk or ride over the minesoil and note all visual differences such as
color, texture, surface elevation, erosion, volunteer vegetation, and wet
spots.
2. Draw a map of the minesoil dividing the surface area into different
sampling units. NOTE: These subdivisions are made on the basis of visual
differences as noted in step 1.
3. After the map of the area has been drawn and all sampling subdivisions
have been made, examine the area once more to be sure that everything has
been taken into account. Record longitude, latitude, and surface elevation
of sampling area.
k. Do either 2.3.2.5.1 or 2.3.2.5.2.
2.3.2.5.1 Profile Sampling—
1. After deciding where the profile will be placed, take the spud bar and
long handled shovel and dig a pit vertically from the surface to a depth of
100 cm.
2. After the pit has been dug so that a vertical cross section of the
minesoil is exposed, describe the minesoil according to method 2.3.1.
3. Take a sample from each layer that has been described according to
2.3.1. Also, any major variations within a layer, such as pockets of
dissimilar material that are of special interest, should be sampled.
k. All samples should be labeled as to pit number, layer number, depth,
etc. NOTE: The more information gathered about a particular sample, the
more useful the sample.
5. Pass all samples for a particular layer through a sieve with 1.6 cm
openings and into a large plastic bag. Discard all material caught on the
sieve after visually estimating the percentage of the total sample retained
on the sieve. This information should be recorded and included in the final
interpretation.
6. After sample has been put into labeled plastic bag, tie bag with twine
and transport to laboratory.
2.3.2.5.2 Surface Sampling—
1. After the area has been subdivided into different units, determine the
number of samples required per subdivision. NOTE: At least one sample
per subdivision should be taken; however, depending on what analyses and
what variability may be contained in one subdivision, more samples can be
taken. Three samples per subdivision are preferred. If only pH is to be
tested, take as many small samples (sandwich baggies full of material) as
possible per each subdivision.
39
-------
2. In each subdivision take representative samples of the 0 to 7-6 cm
depth with a paddy shovel. NOTE: If a minesoil has been "topsoiled" with
material that can be worked with farm implements, the samples are taken
from the surface to a depth of l6 cm.
3. Pour sample from paddy shovel into a plastic ice bag through a sieve
with 7.6 cm openings until bag is three-fourths full. NOTE: A visual
estimate of the percentage of total sample retained on the sieve should
be recorded and included in the ultimate interpretation. The material
retained on the sieve is then discarded.
U. Label the sample bag carefully recording as much information about the
site as possible and date sampled. Also record this information in the
record book.
5. Transport samples back to laboratory.
40
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SECTION 3
SAMPLE PROCESSING AND LABORATORY ANALYSES
3.1 CHARACTERIZING, SUBSAMPLING AND CRUSHING SAMPLES
3.1.1 Characterizing Samples
3.1.1.1 Principle—
Even when careful measures are taken, errors may result in the labeling
and collecting of samples in the field. This procedure is a laboratory
check list to verify that all information was gathered when samples were
collected.
3.1.1.2 Comments—
Samples should be checked for errors as soon as possible after sampling.
The time spent rechecking field data and samples may eliminate missing data,
errors in data, or unnecessary trips back to the sample site to collect
missing information.
3.1.1.3 Chemicals—
None required.
3.1.1.U Materials—
1. Field record book.
2. Collected samples.
3.1.1.5 Procedure—
1. Verify the following:
a. Sample site has been located correctly on a topographic map and
longitude and latitude have been recorded.
b. Surface elevation at sampling site has been recorded.
c. Name, depth, and thickness of coal Seam(s) scheduled for mining have
been recorded.
41
-------
d. Total overburden thickness has been recorded.
e. For each sample the correct site location, sample number, soil or rock
type (if done in field), sampling interval represented by sample, depth from
surface, and date sampled have been recorded in the record book. NOTE: Both
the interval represented by the sample and the depth from the surface should
be recorded even though one can be calculated from the other.
2. For each overburden column, check to make sure that each sample
container has a sample, is numbered correctly, and is labeled correctly.
3. Determine rock type in the laboratory if not completed in the field.
U. Determine color in the laboratory on ground (less than 60 mesh) sample.
3.1.2 Subsampling and Grinding Rock and Native Soil Samples
3.1.2.1 Principle—
Crushing reduces the field sample into a convenient size range for use vith
various laboratory analyses. Samples are crushed, subsampled, and ground to
pass a 0.25 mm (60 mesh) sieve.
3.1.2.2 Comments'—
Crusher and pulverizer should be cleaned after each sample to avoid contam-
ination between samples.
Native soils are soil horizons which are taken above and are treated as an
extension of a core, blast hole, or hand sampled highwall column. Soil and
rock samples should be air dried, not oven dried, before subsampling and
grinding.
3.1.2.3 Chemicals—
None required.
3.1.2.1* Materials—
1. Crusher, chipmunk, motor driven, capable of crushing samples to less
than 6.35 mm (0.25 in) (Cat. No. 5-60836, Sargent-Welch Scientific Company;
or equivalent).
2. Pulverizer, capable of crushing samples to less than 60 mesh (Fen Corp.,
Vickliffe, Ohio, Model PA-M; or equivalent).
3. Mortar and pestle, cast iron (Cat. No. 12-976, Fisher Scientific
Company; or equivalent).
U. Sieve, 0.25 mm openings (60 mesh).
5. Sieve, 6.35 mm (0.25 in) openings (optional).
42
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6. Vials, plastic with snap caps, 1^8 cc (UO drams) capacity.
T« Container, plastic or waxed paper, 1 liter (32 oz) capacity.
3.1.2.3 Procedure (revised and updated from Smith et al., 197*0—
1. Spread sample evenly on a sheet of brown paper and allow to air dry.
NOTE: Sample may have to be mixed periodically to speed drying.
2. After drying, the field sample is split into two representative sub-
samples. One subsample is placed in a container, labeled, and stored for
physical analyses or individual preference tests.
3. The other subsample is crushed to 6.35 mm (0.25 in) or smaller with a
Chipmunk crusher. If a crusher is not available, the material can be
crushed using a hammer or mortar and pestle until it passes through a sieve
with 6.35 mm openings. NOTE: This step may be omitted on most native soil
samples.
k. Place sample in 1 liter container and cover. NOTE: Containers should
not be more than two-thirds full or mixing (step 5) will be impaired.
5. Tumble container end-over-end until material is thoroughly mixed.
6. Place three heaping teaspoons of the mixed material in the pulverizer.
Material is pulverized until it passes a 0.25 mm (60 mesh) sieve. NOTE: A
cast iron mortar and pestle can be substituted for the pulverizer.
7. Place pulverized material in plastic vial for laboratory use.
8. Label vial with the sample identification shown on the field container.
9- Mix sample thoroughly by tumbling the vial end-over-end before sub-
sampling for laboratory procedures (primarily chemical analyses).
3.1.3 Subsampling and Grinding Minesoil Samples
3.1.3.1 Principle—
See 3.1.2.1
3.1.3.2 Comments—
Samples should be air dried before processing begins. Samples should never
be oven dried before processing.
Pulverizer should be cleaned after each sample to avoid contamination
between samples.
3.1.3.3 Chemicals—
Hone required.
43
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3.1.3.U Materials—
1.- Wooden rolling pin (kitchen style).
2. Pulverizer, capable of crushing samples to less than 60 mesh (Fen. Corp.,
Wickliffe, Ohio, Model PA-M; or equivalent).
3. Sieve, 20 cm (8 in) diameter, 19 mm (0.75 in) openings.
k. Sieve, 20 cm (8 in) diameter, 6.35 mm (0.25 in) openings.
5. Heavy brown kraft paper.
6. Vials, plastic with snap caps, 148 cc (ko drams) capacity.
7. Containers, large enough to contain sample fractions.
8. Large spatula.
3.1.3.5 Procedure—
1. Pour field sample out onto a large square of brown paper. Spread
material evenly and allow to air dry. NOTE: Sample may have to be mixed
periodically to speed drying.
2. After drying, the field sample is split into two representative
subsamples. One subsample is placed in a container, labeled, and stored
for physical analyses or individual preference tests.
3. The other subsample is placed between two sheets of brown paper and
crushed by moderately rolling over the top sheet with a rolling pin. This
process is continued until the entire field sample has been processed.
NOTE: Do not allow paper fragments to become incorporated with the soil
sample. Do not crush rock fragments.
k. Pass the crushed material through a sieve with 19 mm openings and
discard material retained on the sieve.
5. All material passing the 19 mm sieve is crushed to pass through a
sieve with 6.35 Him openings.
6. Place sieved sample in a 1 liter container and cover. NOTE: Container
should not be more than two-thirds full or mixing (step 7) will be impaired.
7. Tumble container end-over-end until material is thoroughly mixed.
8. Place three heaping teaspoons of the mixed material in the pulverizer.
Material is pulverized until it passes a 0.25 mm (60 mesh) sieve. NOTE: A
cast iron mortar and pestle can be substituted for the pulverizer.
9. Place pulverized material in a plastic vial for laboratory use.
44
-------
10. Label vial with the sample identification shown on the field container.
11. Mix sample thoroughly by tumbling the vial end-over-end before
subsampling for laboratory procedures (primarily chemical analyses).
3.2 CHEMICAL METHODS
3.2.1 Summary
Chemical methods for characterizing overburdens and minesoils are given.
For a particular parameter, more than one method may be listed. This will
allow the user of the manual some freedom of choice.
The determination of toxic or hontoxic materials due to acidity is over-
riding in importance in the Appalachian and Eastern and Western Interior
Coal Provinces. The methods for determining toxic or potentially toxic
materials are given high priority and are listed at the very front of the
chapter. Methods 3.2.2, 3.2.3, 3.2.H, and 3.2.6 are used to determine the
acid-base balance of minesoils and overburdens.
Next in importance is the nutrient status of the overburden materials.
Nutrient status can be measured by using methods 3.2.5S 3.2.6, and 3.2.15.
These methods give a measure of plant nutrients such as phosphorus,
potassium, calcium, magnesium, and nitrogen. A knowledge of what plant
nutrients are contained in an overburden material enables the mine operator
to efficiently plan the mining operation so that full advantage can be
taken of these nutrients in the resulting minesoil.
For more intensive study of minesoils and overburden materials, procedures
for determining the cation exchange capacity (3.2.16 and 3.2.17) are given.
Ways of estimating the lime requirement in minesols are presented in
methods 3.2.7 through 3.2.10. Also, methods applicable to arid and semi-
arid regions have been included.
3.2.2 Paste pH
3.2.2.1 Principle—
Perhaps the most commonly measured soil characteristic is pH. Soil pH was
defined by Sorensen (1909) as the negative logarithm of the hydrogen-ion
concentration. However, in actuality, hydrogen-ion activity is measured
instead of hydrogen-ion concentration.
Soil pH is measured by a glass electrode incorporated with a pH meter for
this procedure. Water is added to the sample forming a paste. The electrode
is placed in the paste with pH being read directly from the meter.
3.2.2.2 Comments—
Six factors affecting the measurement of pH are: (l) drying the soil sample
during preparation; (2) soil:water ratio used; (3) soluble salts content;
-------
seasonally influenced carbon dioxide content; (5) amount of grinding
given the soil; and (6) electrode junction potential (Jackson, 1958; Peech,
1965).
Care must be taken to insure electrode life and accurate pH measurements:
(l) Electrode should not remain in the sample longer than necessary for
a reading, especially if more alkaline than pH 9-0. (2) Electrode should
be washed with a jet of distilled water from a wash bottle after every
measurement (sample or buffer solution). (3) Electrode should be dipped
in dilute (I part acid to 3 parts water) hydrochloric acid for a few seconds
and washed with distilled water to remove any calcium carbonate film which
may form, especially from alkaline samples. (4) Drying out of the electrode
should be avoided. Electrode is cleaned and suspended in distilled water
(which is protected from evaporation) for storage. (6) Place pH meter in
standby position when electrode is not in a solution (Jackson, 1958; Peech,
1965).
The pH meter and electrode should be standardized with buffers differing by
3 or k pH units, such as k.O and 7.0, before beginning a series of
measurements. After every tenth measurement, recheck the standardization
with both buffers. Care should be taken not to contaminate one buffer
with the other buffer or with the test solution. Never return used
standard buffers to their stock bottles. The procedure describes the
technique for measuring pH with a glass electrode and meter. If pH is
taken in the field using color paper strips or indicator solutions,
modification will have to be made by qualified personnel to the procedure.
3.2.2.3 Chemicals—
1. Standard buffer solutions, pH ^.00 and pH 7.00.
2. Distilled water (H20).
3.2.2.k Materials—
1. pH meter (Corning model 12 or equivalent) equipped with combination
electrode.
2. Paper cups, 30 ml (l oz) capacity.
3. Plastic cups.
k. Stirring rod.
5. Wash bottle containing distilled water.
6. Balance, can be read to 0.1 g.
3.2.2.5 Procedure—
1. Turn on, adjust temperature setting, and "zero" pH meter per
instruction manual.
46
-------
2. Place pH ^.0 and pH 7.0 standard buffers in two plastic cups (one
buffer in each cup). NOTE: NEVER return used buffers to stock bottles.
3. Place electrode in the pH 7.0 buffer.
k. Adjust pH meter to read pH 7.0.
5. Remove electrode from buffer solution and wash with a jet of distilled
water from a wash bottle.
6. Place electrode in the pH U.O buffer and check the pH reading. NOTE:
If pH meter varies more than +_ 0.1 pH units from 4.0, something is wrong
with the pH meter, electrode, or buffers.
7. Weigh 10 g of less than 60 mesh material into a paper cup.
8. Add 5 ml of distilled water to sample. NOTE: Do not stir! Allow water
to wet sample by capillary action without stirring. With most overburden and
minesoils materials, the 2:1 (soil:water) ratio provides a satisfactory paste
for pH measurements; however, for the very coarse textured and the very fine
textured material, more material or water can be added to bring the soil near
saturation. At near saturation conditions, water should not be puddled nor
dry soil appear at the surface.
9. Stir sample with a spatula until a thin paste is formed adding more
water or soil as required to keep soil at saturation point. NOTE: At
saturation, the soil paste glistens as it reflects light and the mixture
slides off the spatula easily. Wash the spatula with a jet of distilled
water before stirring another sample.
10. Place electrode in paste and move carefully about to insure removal of
water film around the electrode. CAUTION: Do not trap particles between
electrode and inside surface of the sample container. Electrodes are
easily scratched. Contact between paste and electrode should be gentle to
avoid both impact and scratching damage, especially in sandy samples.
11. When reading remains constant, record pH and remove electrode from
paste. Carefully wash electrode with distilled water to insure removal of
all paste. If all pH measurements are completed, the electrode should be
stored in a beaker of distilled water. NOTE: After every 10 samples, check
meter calibration with standard buffers.
3.2.3 Neutralization Potential
3.2.3.1 Principles—
The amount of neutralizing bases, including carbonates, present in over-
burden materials is found by treating a sample with a known excess of
standardized hydrochloric acid. The sample and acid are heated to insure
that the reaction between the acid and the neutralizers goes to completion.
47
-------
The calcium carbonate equivalent of the sample is obtained by determining
the amount of unconsumed acid by titration with standardized sodium
hydroxide (Jackson, 1958).
3.2.3.2 Comments —
A fizz rating of the neutralization potential is made for each sample to
insure the addition of sufficient acid to react all the calcium carbonate
present.
During digestion, do not boil samples. If boiling occurs, discard sample
and rerun. Before titrating with acid, fill buret with acid and drain
completely. Before titrating with base, fill buret with base and drain
completely to assure that free titrant is being added to the sample.
3.2.3.3 Chemicals —
1. Carbon dioxide- free water: Heat distilled water just to boiling in a
beaker. Allow to cool slightly and pour into a container equipped with
ascarite tube. Cool to room temperature before using.
2. Hydrochloric acid (HCl) solution, 0.1 N_, certified grade (Fisher So-A-5^
or equivalent).
3. Sodium hydroxide (NaOH) , approximately 0.5 II: Dissolve 20.0 g of NaOH
pellets in carbon dioxide-free water and dilute to 1 liter. Protect from
C02 in the air with ascarite tube. Standardize solution by placing 50 ml of
certified 0.1 N_ HCl in a beaker and titrating with the prepared 0.5 N_ NaOH
until a pH of 7.00 is obtained, Calculate the Normality of the NaOH using
the following equation:
N2 = NjV/v^ where:
Vj_ = Volume of HCl used.
N-L = Normality of HCl used.
V2 = Volume of NaOH used.
N2 = Calculated Normality of NaOH.
k. Sodium hydroxide (NaOH) approximately 0.1 N_: Dilute 200 ml of 0.5 N_
NaOH with carbon dioxide-free water to a volume of 1 liter. Protect from
C02 in air with ascarite tube. Standardize solution by placing 20 ml of
certified 0.1 If HCl in a beaker and titrating with the prepared 0.1 N. NaOH
until a pH of 7.00 is obtained. Calculate the Normality of the NaOH using
the equation in 3.2.3.3 No. 3.
5. Hydrochloric acid (HCl), approximately 0.5 N_: Dilute 1*2 ml of concen-
trated HCl to a volume of 1 liter with distilled water. Standardize solution
by placing 20 ml of the known Normality NaOH prepared in 3.2.3.3 No. 3 in a
beaker and titrating with the prepared HCl until a pH of 7-00 is obtained.
U8
-------
Calculate the Normality of the HC1 using the following equation:
% = tS2V2)/Vlt where:
V2 = Volume of NaOH used.
N2 = normality of NaOH used.
Vx = Volume of HC1 used.
NI = Calculated Normality of HC1.
6. Hydrochloric acid (HCl), approximately 0.1 N: Dilute 200 ml of 0.5 N
HC1 to a volume of 1 liter with distilled water. Standardize solution as
in 3.2.3.3.5, but use 20 ml of the known Normality NaOH prepared in 3.2.3.3
No. k.
7. Hydrochloric acid (HCl), 1 part acid to 3 parts water: Dilute 250 ml of
concentrated HCl with 750 ml of distilled water.
3.2.3.4 Materials—
1. Flasks, Erlenmeyer, 250 ml.
2. Buret, 100 ml (one required for each acid and one for each base).
3. Hotplate, steam bath can be substituted.
U. pH meter (Corning Model 12 or equivalent) equipped with combination
electrode.
5. Balance, can be read to 0.01 g.
3.2.3.5 Procedure (revised and updated from Smith et al., 197*0—
1. Place approximately 0.5 g of sample (less than 60 mesh) on a piece of
aluminum foil.
2. Add one or two drops of 1:3 HCl to the sample. The presence of CaCOj
is indicated by a bubbling or audible "fizz."
3. Rate the bubbling or "fizz" in step 2 as indicated in Table 1.
k. Weigh 2.00 g of sample (less than 60 mesh) into a 250 ml Erlenmeyer
flask.
5. Carefully add HCl indicated by Table 1 into the flask containing sample.
6. Heat nearly to boiling, swirling flask every 5 minutes, until reaction
is complete. NOTE: Reaction is complete when no gas evolution is visible
and particles settle evenly over the bottom of the flask.
49
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TABLE 1. VOLUME AMD NORMALITY OF HYDROCHLORIC ACID USED FOR EACH FIZZ
RATING
Fizz Rating
None
Slight
Moderate
Strong
(ml)
20
Uo
ho
80
HCl
(Normality)
0.1
0.1
. 0.5
0.5
7. Add distilled vater to make a total volume of 125 ml.
8. Boil contents of flask for one minute and cool to slightly above room
temperature. Cover tightly and cool to room temperature. CAUTION: Do not
place rubber stopper in hot flask as it may implode upon cooling.
9. Titrate using 0.1 N_NaOH or 0.5 N.NaOH (concentration exactly known), to
pH 7.0 using an electrometric pH meter and buret. The concentration of NaOH
used in the titration should correspond to the concentration of the HCl used
in step 5. NOTE: Titrate with NaOH until a constant reading of pH 7.0
remains for at least 30 seconds.
10. If less than 3 ml of the NaOH is required to obtain a pH of 7.0, it is
likely that the HCl added was not sufficient to neutralize all of the base
present in the 2.00 g sample. A duplicate sample should be run using the
next higher volume or concentration of acid as indicated in Table 1.
11. Run a blank for each volume or normality of acid using steps 5,7, 8,
and 9.
3.2.3.6 Calculations—
1. Constant (C) = (ml acid in blank)/(ml base in blank).
2. ml acid consumed = (ml acid added) - (ml base added X C).
3. Tons CaC03 equivalent/thousand tons of material = (ml of acid consumed)
X (25.0) X (N of acid).
50
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3.2.U Maximum Potential Acidity by Total Sulfur Determination
3.2.U.I Principles—
This method measures the total sulfur in a sample. If all of the total
sulfur occurs in pyritic forms, the calculation of maximum potential acidity
from sulfur corresponds with actual potential acidity from sulfur. But if
part of the sulfur occurs in other forms, the maximum as calculated will be
too high. This is the reason that such calculations are referred to as
maximums and in doubtful cases approximate determinations should be made
which rule out other sulfur forms (see 3.2.6). These determinations are
not necessary when the maximum acid from total sulfur is within safe limits.
A sample is heated to approximately l600°C. A stream of oxygen is passed
through the sample during the heating period. Sulfur dioxide is released
from the sample and collected in a dilute hydrochloric acid solution
containing potassium iodide, starch, and a small amount of potassium iodate.
This solution is automatically titrated with a standard potassium iodate
solution.
A trace amount of potassium iodate reacts with potassium iodide and dilute
hydrochloric acid to yield free iodine, potassium chloride and water. The
free iodine combines with the sulfur dioxide and water to yield sulfuric
acid and hydroiodic acid. The amount of potassium iodate solution used
during the titration is recorded. The calculation of the percent total
sulfur is based on the potassium iodate measurement (Smith et al., 197^).
3.2.^.2 Comments—
Some samples, e.g. coal, when first placed in the furnace may change the
color of the solution in the titration vessel to pink or purple (probably due
to organic compounds). Some samples may contain halogens (iodine, chlorine,
fluorine) which darken the solution in the titration vessel and will there-
fore produce results that are low. The halogen problem, if encountered, may
be eliminated by the use of an antimony trap between the furnace and
titration assembly. Interference may result with samples high in nitrogen;
however, this does not appear to happen with rock samples. Additional
information can be obtained by reading Leco Equipment Application 120 and
Instructions for Analysis of Sulfur in Hydrocarbons by the Leco High
Frequency Combustion Titration Procedure.
Materials with a low chroma (2 or less) may have a high (over 1.0$) sulfur
content; therefore, use a 0.250 g sample when the chroma of the material is
1 or 2. If the chroma of the material is zero, a 0.100 g sample is used. If
sulfur is not detectable or more accurate values are desired in this sample
size, increase to next highest sample size and rerun.
Read entire manuals on both the Leco Induction Furnace and the Automatic
Titrator.
Periodically clean titration chamber and associated glassware with acetone
or concentrated hydrochloric acid and rinse thoroughly with distilled water.
51
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The following procedure is for use with a LEGO Induction Furnace, Model 521
with Automatic Sulfur Titrator, Model 532. Other similar or advanced models
of this instrumentation may perform equally well; however, the following
procedure will require detailed modifications by a qualified' person for
application to other instruments.
3.2.^.3 Chemicals'—
1. Iron chip accelerator (Leco number 501-077).
2. Iron powder accelerator (Leco number 501-078).
3. Copper ring (Leco number 550-189).
k. Magnesium oxide (MgO).
5. Potassium iodate (003), 0.0052 N_: Dissolve 1.110 g KI03 in distilled
water and dilute to 1 liter.
6. Hydrochloric acid (HCl) solution: Dilute 15 ml of concentrated HC1 to a
volume of 1 liter with distilled water.
7. Arrowroot starch solution: Dissolve U.O g of arrowroot starch (Leco
number 501-06l) in 100 ml of distilled water in a 250 ml beaker. Stir on
a mechanical stirrer with a stirring bar. While starch is stirring, boil
300 ml of distilled and deionized water in a 600 ml beaker. Remove from
heat when boiling point is reached. Remove starch from stirrer. Place
boiled water on mechanical stirrer with stirring bar. While water is
continually stirring, add 5 ml of starch mixture in 20 second intervals
until all starch solution has been added. Place a small amount of the
solution in the 600 ml beaker back into the 250 ml beaker that contained
the starch mixture. Wash beaker by hard swirling and then pour contents
back into the 600 ml beaker. Continue stirring solution in the 600 ml beaker
allowing solution to cool to kO°C. Add 12.0 g of potassium iodide (Kl).
Continue stirring for 15 to 20 minutes.
8. Potassium iodide (Kl).
9- Sulfur standards (Leco number 501-502).
3.2.4.U Materials—
1. Leco Automatic Sulfur Analyzer, package unit, number 63J+-700.
2. Scoops, 0.2 ml volume.
3. Ceramic crucibles with porous covers.
k. Carboys, 19 liters (5 gal).
5. Tongs.
52
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6. Glass wool.
T. Oxygen regulators.
8. Mechanical stirrer.
9. Stirring bar.
10. Combustion tube, hydrocarbon (Leco number 519-OOH).
11. Hot plate.
12. Balance, can be read to 0.001 g.
3.2.^.5 Procedure (revised and updated from Smith et al., 197*0 —
NOTE: Read entire manuals on Leco Furnace, Automatic Titrator and this
entire procedure before starting.
1. Place one level scoop of iron chips in crucible.
2. Weigh 0.500 g of sample (less than 60 mesh) into the crucible.
NOTE: For samples that are suspected to contain over 1% sulfur or have a
chroma of less than 2, see 3.2.4.2.
3. Add one scoop MgO.
4. Add one copper ring and then one scoop of iron powder.
5. Gently shake the crucible to evenly cover the bottom and place one
porous cover on the crucible.
6. Turn on "Filament Voltage" grid tap to medium position.
T. Wait for one minute then turn "High Voltage" switch to ON.
8. Set "Titrate-Endpoint" switch to its middle position.
9. Turn on titrator (upper left switch above "Endpoint Adjust").
10. Drain "Titration Vessel" completely.
11. Set timer switch to ON, adjust timer to 10 minutes, or a time
sufficient to satisfy steps 25, 26, and 27.
12. Slosh carboys containing HC1 and KLO^ to mix the condensate on the
walls of the container.
13. Fill "lodate Buret."
53
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ll*. Fill "Titration Vessel" approximately one-third full with the HC1
solution.
15. Turn on oxygen. Set the pressure to 15 psi, and the flow rate to 1.0
liter per minute. ROTE: Oxygen flow must be started before starch is added.
16. Raise the "Locking Mechanism Handle" WITHOUT a sample crucible on the
pedestal, and lock in place. NOTE: Make sure there is an airtight contact
between sample platform and combustion chamber by observing a vigorous
bubbling in the "Titration Vessel" chamber.
17. Add one measure (5 ml) of starch solution. NOTE: If solution in
"Titration Vessel" chamber turns turbid or yellow after starch solution is
added, turn off the instrument following steps 33 through 39 and make NEW
starch solution.
18. Set "Titrate-Endpoint" switch to "Endpoint."
19. After a few seconds when tit rant level in "lodate Buret" has stopped
falling (Buret reading should be no more than O.OOU) the solution in the
"Titration Vessel" chamber should be a deep blue. NOTE: If the solution
is a pale blue or almost black, turn off the instrument following steps 33
through 39 and make NEW starch solution.
20. Set "Titrate-Endpoint" switch to middle position and lower "Locking
Mechanism Handle."
21. Refill "lodate Buret."
22. Place sample crucible on pedestal, making sure it is centered, and
carefully raise "Locking Mechanism Handle" and lock in place.
NOTE: Make sure there is an airtight contact between sample platform and
combustion chamber by observing a vigorous bubbling in the "Titration
Vessel" chamber.
23. Set "Titrate-Endpoint" switch to Titrate, or if it is known that sample
will evolve SC>2 slowly, set switch at Endpoint. The Endpoint setting acts
as a "Fine Control" allowing buret valve to discriminate smaller increments.
2k. Push RED button on timer to start analysis.
25. Plate current must go to UOO-U50 ma for at least 2 minutes during the
analysis; if not, reweigh and rerun sample.
26. Adjust rheostat to prevent plate current from exceeding k^Q ma.
27. When buret reading does not change for 2 minutes, and Plate Current
has achieved UOO to ^50 ma, it can be assumed that all of the sulfur has
been removed from the sample. If buret reading is still changing when timer
shuts off instrument, set Timer Switch to OFF, which restarts furnace, leave
furnace on until buret is stable for 2 minutes, then turn Timer Switch to ON.
-------
28. Set "Titrate-Endpoint" to middle position. IMPORTANT; Record
titration reading.
29. Lower sample platform, remove crucible using tongs, place fresh sample
crucible in place, but do not close sample chamber.
NOTE: Slightly drain titrating chamber to maintain original level. Drain,
flush, and refill titrating chamber every 3rd sample, or more often if a
large quantity of titrant was used by'the previous sample (steps 16-22).
30. Refill KI03 buret.
31. Close sample chamber, making sure it is tight. Check endpoint (steps
18, 19 and 21).
32. Go to step 23 and continue until all samples have been processed.
33. Turn "Titrate-Endpoint" switch to mid position.
3^. Turn off main ©2 valve on top of tank.
35. Turn off "High Voltage."
36. Turn off Automatic Titrator.
37. Drain titration chamber; flush twice with a chamber full of HC1 solution
or water, cover and leave chamber full of HC1 solution.
38. If 02 has stopped bubbling in the purifying train, turn off small
knurled valve on gauge outlet.
39. Turn off "Filament Voltage."
3.2.^.6 Calculations—
1. Percent sulfur. NOTE: Percent sulfur is dependent upon the concentra-
tion of potassium iodate titrant and sample size.
A. Using 1.110 g KI03/L and 0.500 g sample (0.005 - 1.00$ sulfur range)
$S = Buret reading X 5.0.
B. Using 1.110 g KI03/L and 0.250 g sample (0.010 - 2.00$ sulfur range)
$S = Buret reading X 10.0.
C. Using 1.110 g KI03/L and 0.100 g sample (0.025 - 5.00$ sulfur range)
%S = Buret reading X 25.0.
2. To convert % sulfur to maximum CaC03 equivalents: Multiply % sulfur
by 31.25 to get tons CaCO^ equivalent/1000 tons of material.
55
-------
3.2.5 Sodium Bicarbonate Ext rac table Phosphorus
3.2.5.1 Principle —
This method is a non-destructive extraction of phosphorus from the surfaces
of particles. The pH of extracting solution remains nearly constant during
the extraction procedure.
The concentration of phosphorous in solution increases in calcareous,
alkaline or neutral soils containing calcium phosphates since the concentra-
tion of calcium decreases due to the precipitation of calcium as calcium
carbonate. In the presence of the solid-phase calcite, the concentration
of calcium is 6 X 10-T M in the extracting solution at equilibrium. As the
pH rises, the phosphorous concentration increases in acid soils containing
aluminum and iron phosphates. Secondary precipitation reactions are reduced
to a minimum in acid and calcareous soils because the aluminum, calcium,
and iron concentrations remain at a low level in this extractant (Olsen and
Dean, 1965).
3.2.5.2 Comments —
Temperature of the ext acting solution and the shaking speed may cause
variations in the results. Phosphorous increases approximately 0.^3 ppm
for each degree rise in temperature between 20° and 30°C for soils testing
between 5 and Uo ppm of phosphorous.
Plastic containers should be used to store the extracting solution. If
glass is used, a fresh solution should be prepared every month, since the
pH tends to increase with time resulting in a higher value for extractable
phosphorous .
This method is especially important for overburdens or minesoil because
carbonates often are present, even when the paste pH is below 7.
A shaking speed of 2 should be used on the Burrell wrist-action shaker.
Other shakers may be used, but when the speed increases greatly from that
of the Burrell shaker, somewhat higher results may be obtained.
3.2.^.3 Chemicals —
1. Sodium bicarbonate (NaHC03), 0.5 M: Dissolve 42.0 g of NaHC03 and
dilute to 1 liter with carbon dioxide-free water (see 3.2.3.3 No 7 l).
Adjust to pH 8.5 with 1 N NaOH. Protect from C02 in air with soda lime
or ascarite in a guard tube. Store in polyethylene container and make
fresh every 2 months.
2. Ammonium molybdate ((m^gMo^l^f^O) : Dissolve 15.0 g of
(NHiJgMo^V^O in 300 ml of warm distilled water. Filter if cloudy
and allow to cool. Gradually add 3^2 ml of 12.0 M (31%) HC1. Dilute
to 1 liter with distilled and deionized water.
56
-------
3. Stannous chloride (SnCl2-2H20), stock solution: Dissolve 10.0 g of
SnCl2-2H20 (large crystals) in 25 ml of 12.0 M (37%} HC1. Store in brown
glass bottle in a refrigerator. Prepare fresh every 2 months.
k. Stannous chloride ( SnCl2 • 2H20 ), dilute solution: Mix 0.5 ml of
SnCl2'2H20 stock solution with 66 ml of distilled water. Prepare
dilute solution for each set of determinations.
5. Potassium phosphate (KH2POi|), standard phosphorus stock solution:
Dissolve 0.1*393 g of KH2PO}j with 500 ml of distilled water and dilute to
1 liter. Add 5 drops of toluene to reduce microbial growth. This is a
100 ppm P standard.
6. Potassium phosphate (KH^Oi^)^ dilute solution: Dilute 20 ml of
KH2PO^ stock solution to 1 liter with distilled water. NOTE: This
solution contains 2 micrograms of P per ml (2 ppm).
7. Toluene
8. Hydrochloric acid (HCl), 12 M (31%).
9. Decolorizing charcoal, Darco G-60 (J. T. Baker Co. or equivalent).
3.2.5.U Materials —
1. Flasks, Erlenmeyer, 50 ml with stoppers.
2. Flasks, volumetric, 25 ml, with caps.
3. Flask, volumetric, 1000 ml.
k. Funnels, 60 mm diameter.
5. Funnel rack.
6. Beakers, 50 ml.
7. Cylinder, graduated 25 ml.
8. Pipet, 20 ml.
9. Pipet, 10 ml.
10. Pipet, 5 ml.
11. Pipet, 1 ml.
12. Filter paper, 110 mm diameter, medium porosity, ashless (Whatman
1*0, S & S 589, or equivalent).
13. Balance, can be read to 0.0001 g.
57
-------
lU. Shaking machine, Wrist-Action (Burrell model BB or equivalent).
15. Colorimeter or Spectrophotometer, with filter or adjustment to
provide 660 nm incident light.
16. Cuvettes or matched test tubes to fit above colorimeter.
17. pH meter (Corning model 12 or equivalent) equipped with combination
electrode.
18. Measuring spoon, 1/U teapoon volume.
3.2.5.5 Procedure (revised and updated from Smith et al., 197*0 —
1. Add 1.250 g of less than 60 mesh rock or soil sample, lA teaspoon
decolorizing carbon, and 25 ml of NaHC03 solution to the 50 ml Erlenmeyer
flask. Stopper the flask.
2. Shake for 30 minutes using a shaking speed of 2 on a Burrell wrist-
action shaker.
3. Filter the suspension. NOTE: Shake flask before pouring suspension
into filter funnel. If filtrate is yellow, add 1/U teaspoon carbon, mix
well and refilter. If filtrate is cloudy, filter using fine porosity
filter paper.
k. Pipet 10 ml of filtrate into a 25 ml volumetric flask. Pipet 10 ml
of H20 into a separate 25 ml volumetric flask (blank). NOTE: If necessary
to interrupt work, stop here, stopper and refrigerate.
5. Slowly add, with a pipet or calibrated dispenser, 5 nil of ammonium
molybdate solution and mix immediately holding the top of the flask tightly
closed. NOTE: Gases are generated during this mixing. The pH of the
solution after adding molybdate should be between 3.0 and k.O. With some
alkaline soils it may be necessary to add more acid in order to assure the
indicated pH for consistent color development. However, with minesoils
studied, 5 ml of molybdate has been sufficient and has avoided excess
acidity with extremely acid samples.
6. Wash down neck of flask with a small amount of water and dilute to
about 22 ml.
7. Pipet 1 ml of the dilute SnCl2 solution into the flask, dilute to
volume' (25 ml) with distilled water, and mix contents immediately.
8. After 10 minutes but less than 20 minutes after adding the dilute
SnCl2 to the flask and mixing, measure the adsorbance (A) of the blue
solution, using the colorimeter or spectrophotometer at 660 nm. Read
and understand instructions for operating the instrument correctly before
using.
58
-------
TABLE 2. STANDARDS FOR SODIUM BICARBONATE EXTRACTABLE PHOSPHORUS
P concentration
(ppm P)
Blank
0.08
0.16
0.21*
0.32
0.1*0
0.1*8
0.56
0.61*
0.72
0.80
0.88
0.96
l.Ol*
Volume of dilute
(2 ppm) P Standard
(ml)
0
1
2
3
1*
5
6
7
8
9
10
11
12
13
Volume of
HcO
(ml)
13
12
11
10
9
8
7
6
5
1*
3
2
1
0
Volume of
NaHCOo
(ml)
5
5
5
5
5
5
5
5
5
5
5
5
5
5
9. Prepare standard curve of P concentration as follows:
a. Using 25 ml volumetric flasks, prepare phosphorus standards from
Table 2.
b. Develop the color as in steps 5 and 7.
c. Make a standard curve by plotting absorbance (A) vs. P concentration
(ppm) on linear graph paper.
d. Find ppm in sample extract by finding absorbance (A) of the extract
on the standard curve and reading ppm of P directly from the curve.
59
-------
3.2.5.6 Calculations—
1. ppm P in the rock or soil = ppm (read from the curve) X 50.
NOTE: The 50 is obtained from the following equation:
50 = (25 ml extracting solution/1.25 g sample) X (25 ml final volume/10
ml extract).
2. pp2m P in the soil = (ppm P in soil) X 2.
3.2.6 HCl-Extractable, HNOg-Extractable and Non-Extractable Total Sulfur
3.2.6.1 Principle—
In doubtful cases, as stated in 3.2.^.1, this method should be used to rule
out HCl-extractable and non-extractable forms of sulfur which are not
considered to be acid formers. The HNOj-extractable sulfur is determined
by calculations. This form of sulfur will react with oxygen to produce acid.
3.2.6.2 Comment s—
It is necessary to remove chlorides and nitrates by water leachings after
the hydrochloric and nitric acid (respectively) extractions before running
total sulfur.
Care should be taken that no sample is lost by run over, splashing or
breaking through the filter paper during all leachings.
3.2.6.3 Chemi c als—
1. Hydrochloric acid (HCl), 2 parts acid to 3 parts water: Mix 1*00 ml of
concentrated HCl with 600 ml of distilled water.
2. Nitric acid (HN03), 1 part acid to 7 parts water: Mix 125 ml of
concentrated HN03 with-875 ml of distilled water.
3. Silver Nitrate (AgN03), 10$: Dissolve 10.0 g of AgN03 in 90 ml of
distilled water. Store in amber bottle away from light.
k. Nessler's Solution (Fisher Scientific Co. No. So-N-2l* or equivalent).
3.2.6. fr Materials—
1. Leco Induction Furnace and Automatic Sulfur Titrator as in 3.2.U.U.
2. Funnels, 28 mm I.D. polyethylene.
3. Filter paper, 5.5 cm glass fiber.
k. Flasks, Erlenmeyer, 250 ml.
60.
-------
5. Beakers, 100 ml.
6. Syringe.
7. Balance, can be read to 0.001 g.
3.2.6.3 Procedure (Revised and updated from Smith et al., 197*0—
1. Take three 0.500 g subsamples of less than 60 mesh material.
2. Take one subsample and analyze for total sulfur (see 3.2.U).
3. Taking care not to sharply crease the glass fibers, fold filter
paper to fit a polyethylene funnel.
k. Place second subsample in, filter. NOTE: Make sure all material is
placed in the filter.
5. Place subsample and filter onto funnel holder in sink or other
suitable pan which can receive outflow from funnel.
6. Using a syringe, pipette, or other graduated dispenser, add 2:3 HC1 to
almost the top of the filter paper. Caution: During this step and all
other leaching steps, be careful not to lose any sample by runover, splashing,
or breaking through the filter paper.
7. Repeat step 6 until a total of 50 ml of acid has been added.
8. Place funnel holder, containing funnel and subsample, over a 100 ml
beaker.
9. Leach subsample with 50 ml of distilled and deionized water.
Discard leachate. NOTE: Stop here if procedure cannot be completed in
one day. CAUTION: Samples must be kept moist.
10. Leach subsample with another 50 ml of distilled and deionized water.
11. Test leachate for chlorides by adding 3 drops of 10$ AgN03 with a
dropper. NOTE: The presence of chlorides will be detected by a white
precipitate.
12. Discard leachate and repeat steps 10 and 11 until no precipitate forms.
13. Discard leachate.
14. Air dry subsample and filter overnight.
15. Carefully fold glass fiber filter around the sample and transfer to
a ceramic crucible for total sulfur analysis (see 3.2.4).
16. Place third subsample in a 250 ml Erlenmeyer flask. NOTE: Make
sure all of the subsample is placed in the flask.
61
-------
17. Add 50 ml of HN03 (l:7).
18. Let stand overnight at room temperature.
19. Taking care not to sharply crease the glass fibers, fold a filter
to fit a polyethylene funnel.
20. Place a funnel holder over a sink or 'other suitable pan which can
receive outflow from funnel.
21. Carefully pour subsample and acid from the Erlenmeyer flask into the
funnel. NOTE: Do not get material above top of filter paper.
22. Repeat step 21 using distilled and deionized water to wash all
materials remaining in the Erlenmeyer flask into the funnel.
23. Place funnel holder containing funnel and subsample over a 100 ml
beaker. NOTE: Stop here if procedure cannot be completed in one day.
CAUTION: Sample must be kept moist.
2k. Leach subsample with 50 ml of distilled and deionized water. Discard
leachate.
25. Leach subsample with another 50 ml of distilled and deionized water.
26. Test leachate for presence of nitrates by adding 3 drops of Nessler's
Solution with a dropper. NOTE: If nitrates are present, the leachate will
turn yellow within 30 seconds as seen against a white background.
27. Discard leachate and repeat steps 25 and 26 until no nitrates are
detected.
28. Discard leachate.
29. Air .dry subsample and filter overnight.
30. Carefully fold glass fiber filter around the sample and transfer to
a ceramic crucible for total sulfur analysis (see 3.2.U).
3.2.6.6 Calculations—
1. HCl-extractable sulfur (mostly sulfates) = (Total sulfur of untreated
sample) minus (Total sulfur after HC1 treatment).
2. HN03-extractable sulfur (mostly pyritic sulfur) = (Total sulfur after
HC1 treatment) minus (Total sulfur after HNOg treatment).
3. Non-extractable sulfur (mostly organic sulfur) = Total sulfur after
HNOo treatment.
62
-------
3.2.7 Lime Requirement By Ca (OH)2 Titration
3.2.T.I Principle--
When calcium hydroxide is added to the soil, it initially reacts with and
neutralizes any acidity in solution. The calcium hydroxide further reacts
with the acidity contained on the soil particles. A time period of four
days is required for the reaction to go to equilibrium. Because 5 ml of
0.0^ II calcium hydroxide is equivalent to 1 ton of pulverized limestone
per 1000 tons of material, various amounts can be added to the sample making
this treatment similar to liming the soil. After the k day incubation period,
pH determinations are made. A titration curve is drawn comparing pH
to the amount of pulverized limestone per 1000 tons of material. From this
curve the amount of pulverized limestone per 1000 tons of material can be
determined to bring the soil to a pH of 6.5 (Dunn, 19^3).
3.2.T.2 Comments—
The calcium hydroxide must be protected from carbon dioxide in the air by
using soda lime or ascarite in a guard tube. The method is time consuming
due to a U day incubation period; however, it is a reliable and accurate
method for determining the lime requirement.
3.2.7.3 Chemicals--
1. Calcium hydroxide (Ca(OH)2)> O.OU K_, saturated solution: Dissolve
1.5 g Ca(OH)2 (use some excess) and dilute to 1 liter with carbon dioxide-
free water (see 3.2.3.3. No. l). Filter to remove calcium carbonate (CaC03)
and protect filtrate from C02 in the air with soda lime or ascarite in a
guard tube.
2. Standard buffer solutions, pH - k.OO and pH - 7=00.
3. Chloroform (CHC13).
3.2.7.^ Materials—
1. Flasks, Erlenmeyer, 250 ml with rubber stoppers.
2. Balance, can be read to 0.1 g.
3. pH meter (Corning model 12 or equivalent) with combination electrode.
3.2.7.5 Procedure'—
1. Place 10 g samples of less than 60 mesh air-dry soil in 7 flasks.
2. Add Ca(OH)2 at the rates of 1/2, 1, 2, 3, 4, 5, 6 tons of pulverized
limestone per 1000 tons of material using 5 ml of 0.0k N_ Ca(OH)2 as the
equivalent of 1 ton of pulverized limestone per 1000 tons of material.
3. Dilute to 100 ml with distilled water.
63
-------
U. Add three drops of chloroform to prevent microbial activity.
5. Allow suspensions to stand in stoppered flasks for k days with
thorough shaking twice a day.
6. After i* day incubation period, calibrate pH meter using pH ^.00 and
7.00 standard buffer solutions (see 3.2.2) and determine suspension pH.
NOTE: Gently swirl the suspension to insure good electrode-suspension
contact.
3.2.7.6 Calculations—
1. Construct a titration curve by plotting pH on the horizontal axis and
tons of pulverized limestone per 1000 tons of material on the vertical axis.
2. Plot points and construct a best-fit curve through the points.
3. Draw a line vertically from pH 6.5 to the curve and put an (X) on the
curve.
k. Draw a line horizontally from the (X) to the vertical axis.
5. Determine tons of pulverized limestone per 1000 tons of material
needed to bring the soil to pH 6.5-
3.2.8 Lime Requirement By the Five Minute Boiling Method
3.2.8.1 Principle—
Calcium hydroxide neutralizes the acidity in solution first and then
reacts with and neutralizes the acidity contained on the soil particles.
This reaction time is greatly reduced by boiling the sample and calcium
hydroxide mixture for 5 minutes and allowing it to cool before a measurement
is taken. The procedure is similar to liming the samples, since 5 ml of
0.0k W calcium hydroxide is equivalent to 1 ton of pulverized limestone per
1000 tons of material. A titration curve is drawn comparing pH to tons of
pulverized limestone per 1000 tons of material. The amount of pulverized
limestone needed to bring the soil to a pH of 6.5 can be read directly from
the curve, (Abruna and Vicente, 1955).
3.2.8.2 Comments—
Because of the 5 minute boiling period, the time element is reduced from
k days (Ca(OH)2 method) to about 1 hour.
The calcium hydroxide must be protected from carbon dioxide in the air by
using soda lime or ascarite in a guard tube.
3.2.8.3 Chemicals—
1. Calcium hydroxide (Ca(OH)2), O.OU N_, saturated solution: Dissolve
1.5 g Ca(OH)2 (use some excess) and dilute to 1 liter with carbon dioxide-
64
-------
free water (See 3.2.3.3 No. l). Filter off calcium carbonate (CaC03) and
protect from COg in the air with soda lime or ascarite in a guard tube.
2. Standard buffer solutions, pH = k.OO and pH =7-00
3.2.8.U Materials—
1. Flasks, Erlenmeyer, 250 ml.
2. Hot plate.
3. Thermometer, 0 - 100°C.
k. Water Tray.
5. Balance, can be read to 0.1 g.
6. pH meter, (Corning model 12 or equivalent) with combination electrode.
3.2.8.5 Procedure—
1. Place 10 g samples of less than 60 mesh air-dry soil in 7 flasks.
2. Add Ca(OH)2 at the rates of 1/2, 1, 2, 3, ^, 5, 6 tons of pulverized
limestone per 1000 tons of material using 5 ml of O.OU N_ Ca(OH)2 as the
equivalent of 1 ton of pulverized limestone per 1000 tons of material.
3. Dilute with 50 ml of distilled water.
k. Boil on a hot plate for 5 minutes. NOTE: Intermittent stirring of the
samples may be necessary to avoid excessive foaming.
5. Cool in water tray to 25°C.
6. Calibrate pH meter using pH ^.00 and 7.00 buffer solutions.
7. Immediately after cooling, determine pH of soil + water + O.OU N_ Ca(OH)2
suspension using a glass electrode. NOTE: Gently swirl the beaker to
insure good electrode-suspension contact.
8. Record pH.
3.2.8.6 Calculations—
See 3.2.7.6.
3.2.9 Lime Requirement by the Woodruff Buffer Method
3.2.9.1 Principle—
The solution used is calcium acetate buffered by p-nitrophendl. An excess
of the buffered solution (at pH 7.0) is added to the sample and allowed to
65
-------
equilibrate for an hour. The pH of the solution is read and the lime
requirement is based on the drop in pH of the buffered solution. By
allowing the buffer solution to stand in contact with the sample, calcium
ions from the solution saturate the exchange complex and hydrogen ions
go into solution, thus lowering the pH (Woodruff, 19U8).
3.2.9.2 Comments—
The method is quick, reliable, and adaptable to use on soils of different
exchange capacities. The Woodruff buffer solution is strongly buffered and
may not accurately detect the lime requirement for weakly acid samples.
On strongly acid minesoil samples, the Woodruff buffer method correlated with
the Ca(OH)2 titration procedure of determining lime requirement (West
Virginia University, 1971).
3,2.9.3 Chemicals—
1. p^Nitrophenol (N02CgHitOH).
2. Calcium acetate (Ca(CH3COO)2=H20).
3. Magnesium oxide (MgO), heavy, powder, laboratory grade (Fisher M-50
or equivalent).
4. Standard buffer solutions, pH = ^.00 and pH = 7-00.
5. Woodruff buffer, stock solution: In a 10 liter glass bottle mix
80.0 g of WOgCgH^OH, 1*00.0 g Ca(CH3COO)2-H20, 6.2 g MgO, and k liters of
distilled water. Make to 10 liters with distilled water. Put on
reciprocating shaker at low speed overnight. Filter solution. Adjust to
pH 7.00 with HC1 or MgO.
6. Woodruff buffer, dilute solution: Mix 20 ml of Woodruff buffer stock
solution with 10 ml of distilled water.
3.2.9.1* Materials —
1. Glass bottle, 10 liter.
2. Shaker, horizontal reciprocating type, 6.3 cm (2.5 in) stroke, 120
strokes per minute.
3. Paper cup or beaker
k. Automatic pipet, 5 ml.
5. Stirrer.
6. pH meter (Corning model 12 or equivalent) with combination electrode.
7. Balance, can be read to O.Olg.
66
-------
3.2.9.5 Procedure—
1. Place 5.0 g of less than 60 mesh sample in a paper cup or beaker.
2. Add 5 ml of distilled water and mix with the soil. Let stand and
mix occasionally for 1 hour.
3. Calibrate pH meter using pH buffer solutions of U.OO and 7.00 (See 3.2.1).
k. Using pH meter, record pH of soil + water mixture by placing an electrode
into the sample while shaking the cup. This insures good electrode contact
with the mixture. NOTE: Soil + water mixture equalling or exceeding pH
6.5 have a lime requirement of zero tons of pulverized limestone per 1000
tons of material.
5. Add 5 ml of the Woodruff buffer stock solution.
6. Stir or shake for at least 30 minutes.
7. Using the dilute Woodruff buffer solution, adjust meter to a reading of
exactly pH = 7.0.
8. Read and record pH of soil + water + Woodruff buffer stock solution
mixture while shaking the cup to insure a good electrode contact. Record
as buffered pH reading.
3.2.9.6 Calculations—
1. pH depression = (7.0) - (buffered pH reading).
2. Lime Requirement (L.R.) in tons pulverized limestone/1000 tons of material
= 0.5 X (pH depression).
3.2.10 Lime Requirement by S.M.P. Buffer
3.2.10.1 Principle.—
By measuring a change in pH of a buffer caused by the acids in a soil,
Shoemaker, McLean, and Pratt (1962) determined the lime requirement of a
soil. The lime requirement is read directly from a table based on pH of
a soil after the S.M.P. buffer has been added.
3.2.10.2 Comments—
The S.M.P. buffer is very reliable for soils with a 2 ton per 1000 ton of
material lime requirement. It adapts well for acid soils with a pH below
5.8 containing less than 10$ organic matter and having appreciable quantities
of soluble aluminum.
A sensitivity of 0.1 pH unit is needed for the interpretation of this method.
A difference of 0.1 pH unit will result in a lime requirement difference of
0.5 to 0.9 tons of lime per 1000 tons of material for mineral soils.
67
-------
Increased exposure time causes greater acidity thus causing a greater lime
requirement. Increases in organic matter and/or clay content increases
absorption of acidic cations. Buffer modifications may be necessary to
prevent interference from hydroxy-iron and hydroxy-aluminum polymers.
Air-dry soils may be stored several months in closed containers without
affecting the SMP pH measurement.
3.2.10.3 Chemicals—
1. Standard buffer solutions, pH = U.OO and pH = 7.00
2. SMP buffer solution : Dissolve 1.8 g p-nitrophenol (NC^CglfyOH), 2.5
ml triethanolamine (C^H^NO-^), 3.0 g potassium chromate (K2CrOi|), 2.0 g
calcium acetate (Caio^CI^^), and 53.1 g calcium chloride (CaCl2'2H20)
with distilled water and dilute to I liter. Filter through a fiberglass
sheet if suspended material is present. Connect an air inlet with a 2.5** X
30.5 cm (1 x 12 in) cylinder of drierite, a 2.51* X 30.5 cm cylinder of
ascarite, and a 2.5^ X 30.5 cm cylinder of drierite in series.
3.2.10.3 Materials—
1. Cup, 50 ml. glass, plastic, or waxed paper of similar size.
2. Pipet, 10 ml capacity.
3. Shaker, horizontal reciprocating type, 6.3 cm (2.5 in) stroke, 250
strokes per minute.
k. pH meter (Corning model 12 or equivalent) with combination electrode.
5. Balance, can be read to 0.1 g.
3.2.10.5 Procedure'—
1. Weigh 5 g of less than 60 mesh sample into a 50 ml cup.
2. Add 5 ml of distilled water. Mix for 5 seconds.
3. Wait for 10 minutes and read the soil pH (see 3.2.2).
k. Add 10 ml SMP buffer solution to the cup for mineral soils with a
pH of 6.5 or less.
5. Shake for 10 minutes on reciprocating shaker at 250 strokes, per
minute or stir.
6. Let stand for 30 minutes.
7. Read pH of the soil-buffer solution to the nearest 0.1 pH unit
(see 3.2.2).
68
-------
TABLE 3. SOIL-SMP BUFFER pH AND CORRESPONDING LIME REQUIREMENT (L.R.)
TO BRING MATERIAL TO pH 6.5*
pH
6.9
6.8
6.7
6.6
6.5
6.U
6.3
6.2
6.1
6.0
5.9
— — — — — — — — — — _ _ ^—
L.R.
(Tons/1000 Tons)**
0.3
1.0
1.8
2. It
3.1
3.9
U.6
5.3
6.1
6.0
5.9
•>MI*M^^^^^^VHV1^VHM^V^V^^^.^^^
pH
5.8
5.7
5.6
5.5
5.U
5.3
5.2
5.1
5.0
U.9
U.8
.•^— ••••^^i.ijim.^. -i..-..— — i— — •—••^ ^^••t
L.R.
(Tons/1000 Tons)*5
8.1
8.9
9.6
10. k
11.1
11.7
12.5
13.2
lU.O
1U.7
15.5
*Adapted from Shoemaker, McLean, and Pratt, 1962.
**Agricultural ground limestone TNP at least
3.2.10.6 Calculations—
Determine lime requirement from Table 3.
3.2.11 Total Sulfur Estimation By Peroxide Oxidation
3.2.11.1 Principles—
Pyritic minerals begin to change into two new products when exposed to the
atmosphere. The change may proceed slowly over a long period of time
before the final products (yellowboy and sulfuric acid) are formed. The
end product, "yellowboy," actually may form only when the sulfate is
partially or completely neutralized by a basic substance. The chemical
equation for this complete change in pyrite follows:
69
-------
Pyrite + Oxygen + Water equals Yellowboy + Sufluric Acid
+ 1502 + lUH20 = UFe(OH)3
Hydrogen peroxide greatly reduced the time needed for pyrite to oxidize to
sulfuric acid and yellowboy.
3.2.11.2 Comments' —
Alkaline materials interfere with the efficiency of hydrogen peroxide in
oxidizing pyrite; therefore, overburden rock and minesoil samples containing
carbonates need to be leached with acid and water as prescribed in steps
2 through 5 of the procedure.
When samples contain readily oxidizable organic matter, step 7 in the
procedure may have to be repeated until the reaction stops.
The hydrogen peroxide used in this method must be 30% hydrogen peroxide.
It must not contain stabilizers.
An important thing to remember is that this procedure works with fresh
overburden and not with complex mixtures of minesoil material.
3.2.11. 3 Chemicals—
1. Silver nitrate (AgNC>3), 10$: Dissolve 10.0 g of AgN03 with distilled
water and make to a volume of 100 ml. Store in brown bottle away from light.
2. Hydrochloric acid (HCl), 2 parts acid to 3 parts water: Mix kOO ml
of concentrated HCl with 600 ml of distilled water.
3. Hydrogen peroxide (H202), 30% (Fisher certified Wo. H-325 or equivalent).
h. Sodium hydroxide (NaOH), 1.0 N_: Dissolve 1*0.0 g of NaOH pellets in
carbon dioxide-free water (see 3.2.3.3. No. l) and make to a volume of 1
liter. Protect from C02 in air with ascarite tube.
5. Sodium hydroxide (NaOH), 0.1 N: Dilute 10 ml of 1.0 N_ NaOH to a
volume of 1 liter with carbon dioxide-free water (see 3.2.3.3. No. l).
Standardize solution (see 3.2.3.3. No. U). Protect from C02 in air with
ascarite tube.
3.2.11.1* Materials—
1. Sample, ground to pass a 60 mesh sieve.
2. Funnels.
3. Hotplate. NOTE: Bunsen burner may be substituted.
k. Thermometer, °C.
70
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5. Beakers, 300 ml tall form.
6. Graduated cylinder, 25 ml.
7. Glass fiber filter (Reeve Angel 93UAH or equivalent).
8. Burets, 50 ml capacity.
9. Balance, can be read to 0.01 g.
10. pH Meter (Corning Model 12 or equivalent) with combination electrode.
3.2.11.5 Procedure (modified and updated from Smith et al., 197^)—
1. Weigh 2.00 grams of less than 60 mesh sample.
NOTE: If the sample contains no carbonates and no sulfates, and the paste
pH is less than 5.5» then steps 2 through 5 can be eliminated and procedure
can be continued at step 6.
2. Place sample into a funnel fitted with filter paper and leach with 200 ml
of 2:3 HC1 in funnel-full increments.
3. Leach sample with distilled water (in funnel-full increments) until
effluent is free from chloride as detected by 10$ silver nitrate. Note: Add
three drops of silver nitrate. If a white precipitate forms, chlorides are
present.
k. Air dry filter and sample overnight, or place in 50°C forced air oven
until dry.
5. Carefully scrape dried sample from filter surface and mix sample.
6. Place sample in a 300 ml tall form beaker.
7. Add 2U ml of 30% R2®2 an<^ heat beaker on hotplate until solution is
approximately ^0°C. Remove beaker from hotplate and allow reaction to go to
completion as shown when bubbling ceases. NOTE: Three blanks for each
batch of samples should be handled in the same manner. CAUTION: Initial
reaction jnay be quite turbulent when samples contain more than 0.1$ sulfur.
8. Add an additional 12 ml of H202 (30$) to beaker and allow reaction to
go to completion as shown when bubbling ceases.
9. Place beaker on hotplate and heat to approximately 90 to 95°C, solution
temperature, until any unreacted ~&2^2 left in beaker is destroyed as shown
when bubbling ceases. Do not allow to go to dryness.
10. Wash down the sides of the beaker with distilled water and make the
volume of the solution to approximately 100 ml.
71
-------
11. Place beaker on the hotplate and heat the solution to boiling to drive
off any dissolved C02, then cool the solution to room temperature.
12. Titrate the solution with 0.0100 N NaOH, that is free to C02 and
protected from the atmosphere, to pH T.O using a pH meter.
3.2.11.6 Calculations—
1. meq H+/100 g = (ml of NaOH) X (N of NaOH) X (lOOg/weight of sample).
2. % S = 0.0185 (meq ffVlOOg) - 0.08o6. (Grube, et al., 1973).
3. To convert percent sulfur (% S) to maximum CaCO^ equivalents: Multiply
7<>S by 31.25 to get tons CaCOg equivalent/1000 tons of material.
3.2.12 Double Acid Extractable Phosphorus, Potassium, Calcium, and Magnesium
3.2.12.1 Principle—
The method is a modified North Carolina Double Acid Method first published
by Mehlich (1953) and then by Nelson, Mehlich and Winters (1953).
Phosphorus, potassium, calcium, and magnesium are extracted from the sample
using a solution containing dilute hydrochloric and sulfuric acid.
Phosphorus concentration in the extract is determined using a colorimeter
and calibration curve. The concentrations of potassium, calcium, and
magnesium in the extract are determined using an atomic absorption spectro-
photometer and calibration curve. The concentrations of each element can
then be converted into pounds/1000 tons by calculations.
3.2.12.2 Comments—
With some soils a light to dark yellow color may develop in the extract.
Decolorization is accomplished by the addition of activated charcoal in
the extraction procedure. Lanthanum is added as a compensating element
to remove phosphate and sulfate interference in the atomic absorption
spectrophotometer methods for calcium and magnesium.
After the initial extraction, individual elements can be determined if
data for all four elements are not required. Samples with elements higher
in concentration than given in the calibration curves must be diluted and
the resulting reading multiplied by the dilution factor.
3.2.12.3 Chemicals—
1. Hydrochloric acid (HCl), concentrated.
2. Sulfuric acid (^SO), concentrated.
3. Extracting solution: To make 0.05 N. HCl and 0.025 N H2SO^, measure
about 10 liters deionized water into an 18 liter pyrex bottle. Add 12 ml
H2SOij. (96/S) and 73 ml HCl (31%). Make to 18 liters with distilled, water
and mix thoroughly by shaking. Allow 12 hours to come to equilibrium.
72
-------
U . Ammonium molybdate ( (WIty ) (SM
5. Ammonium vanadate (NH^V03).
6. Nitric acid (HN03), 1 N_: Dilute 6^ ml of concentrated HN03 (69.
to 1 liter with distilled water.
7. Molybdate - Vanadate solution: Dissolve 25 g of (Nlty ^MoyC^V^I^O in
500 ml of distilled water. Dissolve 1.25 g of NH^V03 in 500 ml of 1 N.
HN03. Store in separate bottles. Mix equal volumes of these solutions
(l ml required per sample). Prepare fresh mixture each week.
8. Monobasic potassium phosphate (KI^POlj).
9. Phosphorus standard solution: Dissolve 0.1098 g of KH2P04 in 500 ml
of extracting solution. Dilute to 1 liter with extracting solution.
10. Potassium atomic absorption standard (1000 ppm).
11. Calcium atomic absorption standard (1000 ppm).
12. Magnesium atomic absorption standard (1000 ppm).
13. Potassium (K) standard stock solution (100 ppm): Place 10 ml of
potassium atomic absorption standard (1000 ppm) in a 100 ml volumetric
flask. Bring to volume with deionized water. Make fresh daily.
Ik. Calcium (Ca) standard stock solution (200 ppm): Place 20 ml of
calcium atomic absorption standard (1000 ppm) in a 100 ml volumetric flask.
Bring to a volume with deionized water. Make fresh daily.
15. Magnesium (Mg) standard stock solution (100 ppm): Place 10 ml of
magnesium atomic absorption standard (1000 ppm) in a 100 ml volumetric
flask and dilute to volume with deionized water. Make fresh daily.
16. Lanthanum chloride (LaCl3«6H20) , 5$: Dissolve 127 g of LaCl3-6H20
with deionized water and bring to a volume of 1 liter.
17. Activated charcoal (Darco G-60 or equivalent).
3. 2. 12. It Materials—
1. Atomic absorption spectrophotometer (Perkin-Elmer Model U03 or
equivalent ) .
2. Colorimeter (Bausch and Lomb Spectronic 20 or equivalent).
3. Flasks, Erlenmeyer, 50 ml.
h. Flasks, volumetric, 100 ml.
5. Flasks, volumetric, 200 ml.
73
-------
6. Pipet, 1 ml.
7. Pipet, 2 ml.
8. Shaker, horizontal reciprocating type, 6.35 cm (2.5 in) stroke with
120 strokes per minute.
9. Filter paper (Whatman ^0 or equivalent).
10. Pyrex bottle, 18 liters.
11. Pyrex bottle, 8 liters.
12. Balance, can be read to 0.1 g.
3.2.12.5 Procedure—
1. Place 5.0 g of less than 60 mesh sample in a 50 ml Erlenmeyer flask.
Add 0.2 g of activated charcoal. Prepare two blanks using only 0.2 g
of activated charcoal.
2. Add 25 ml of extracting solution and shake for 5 minutes on the
reciprocating shaker at 120 strokes per minute.
3. Filter using filter paper and save filtrate for P, K, Ca, and Mg
determinations. NOTE: If filtrate is cloudy, refilter.
h. Subdivisions 3.2.12.5.1 through 3.2.12.5.3 include the determination
of individual elements.
3.2.12.5.1 Phosphorus (P)—These steps are used for the determination of
phosphorus.
v
1. Turn on colorimeter 15 minutes before use and adjust according to
instruction manual.
2. Pipet h ml of filtered extract into a colorimeter tube.
3. Add 1 ml of molybdate-vanadate solution and allow to stand 10 minutes.
k. Mix by inverting tube and shaking by hand for a few seconds.
5. Place tube in instrument and read percent transmission (% T).
6. Using % T, determine the ppm available P from a calibration curve
prepared as follows: (A) To separate colorimeter tubes, add the amounts
of chemicals given in Table 4; (B) Treat as outlined in 3.2.12.5.1 steps 2-5;
(C) Plot ppm on the horizontal axis and % T on the vertical axis. NOTE:
If sample does not fall on calibration curve, samples must be diluted, and
results multiplied by the dilution factor. The dilution factor is obtained
by taking the final volume and dividing it by the initial aliquot.
74
-------
TABLE k. PHOSPHORUS (?) STANDARDS
Phosphorus
Standard
Solution
(ml)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
U.O
3.2.12.5.2
Extracting
Solution
(ml)
U.O
3.5
3.0
2.5
2.0
1.5
l.O
0.5
0.0
Potassium (K) — These steps
^••(••••^•MBVH^— ^MIW^B^M^-^W^BW
Molybdate-
Vanadate
Solution
(ml)
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
are used for the
Phosphorus
in
Standard
(ppm)
0.0
2.5
5.0
7.5
10.0
12.5
15.0
IT. 5
20.0
determination of
potassium.
1. Set the atomic absorption spectrophotometer unit on emission mode
following the instrument's instruction manual.
2. Use the extractant for zero setting.
3. Put the extracted sample solution under the aspirating tube and record
readings.
k. Determine ppm of K in the sample from the calibration curve prepared
as follows: (A) Into separate 100 ml volumetric flasks, dilute the K
standard stock solution with extracting solution for a range of 0 to 80 ppm
increments; (B) Take reading with the atomic absorption spectrophotometer;
(C) Plot available K (ppm) on the horizontal axis and instrument reading on
the vertical axis; (D) Plot a curve through the points. NOTE: If samples
do not fall on the calibration curve, dilute samples with extracting
solution and multiply results by dilution factor. The dilution factor
is obtained by dividing the final volume by the initial aliquot.
75
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3.2.12.5.3 Calcium (Ca) and magnesium (Mg)—These steps are used for the
determination of calcium and magnesium.
1. Adjust the atomic absorption spectrophotometer following the instrument
instruction manual.
2. Pipet 1.0 ml of sample extract and blank into separate 100 ml volumetric
flasks. Add 1.0 ml of 5% LaCl3'6H20 to each flask.
3. Bring to volume with extracting solution and mix by hand shaking.
k. In separate 100 ml volumetric flasks, prepare the calcium standards as
shown in Table 5- Aspirate each standard into the instrument until a
steady reading is obtained. Record reading.
5. Make a calibration curve plotting Ca (ppm) on the horizontal axis and
instrument reading on the vertical axis. Plot a curve through the points.
6. Into separate 200 ml volumetric flasks, prepare the magnesium standards
as shown in Table 6. Aspirate each standard into the instrument until a
steady reading is obtained. Record reading.
7. Make a calibration curve plotting extractable Mg (ppm) on the
horizontal axis and instrument reading on the vertical axis. Plot a
curve through the points.
8. Aspirate sample extracts into the atomic absorption spectrophotometer
and record readings.
9. Determine ppm of calcium and magnesium from calibration curves. If
samples do not fall within the range of the calibration curve, dilute
sample with extracting solution and add 5$ LaClg^H^O, but not to exceed
1% La in the final dilution. Multiply results by dilution factor. The
dilution factor is obtained by taking the final volume and dividing it by
the initial aliquot.
3.2.12.6 Calculations—
1. Dilution factor (DF) equals 1 unless the samples have to be diluted to
fall within the range of the standard curve. The dilution factor is obtained
by taking the final volume and dividing it by the initial aliquot.
2. ppm P in the soil = ppm (read from the curve) X 6.25 X DF. NOTE:
The 6.25 is obtained from the following equation: 6.25 = 25 ml extracting
solution/5 g sample) X (5 ml final volume/it ml extract).
3. ppm K in the soil = ppm (read from the curve) X 5 X DF. NOTE: The
5 is obtained from the following equation: 5 = (25 ml extracting solution)/
(5 g sample).
76
-------
TABLE 5. CALCIUM (Ca) STANDARDS
Stock Ca
Solution
200 ppm
(ml)
0.0
1.0
2.0
3.0
lf.0
5.0
Stock Mg
Solution
100 ppm
Ul)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
LaClo'6HpO
(i)
2.0
2.0
2.0
2.0
2.0
2.0
TABLE 6. MAGNESIUM
LaClv6HpO
(ml)
U.O
k.O
U.O
k.O
k.O
k.Q
k.O
Extracting
Solution
(ml)
98.0
97-0
96.0
95.0
9U.O
93.0
(Mg) STANDARDS
Extracting
Solution
(ml)
196.0
195.5
195.0
19^.5
19^.0
193.5
193.0
Calcium
in
Standard
(ppm)
0.0
2.0
k.O
6.0
8.0
10.0
Magnesium
in
Standard
(ppm)
0.00
0.25
0.50
O.T5
1.00
1.25
1.50
77
-------
U. ppm Ca in the soil = ppm (read from the curve) X 500 X DF. NOTE:
The 500 is obtained from the following equation: 500 = (25 ml extracting
solution/5 g sample) X (100 ml final volume/1 ml extract).
5. ppm Mg in the soil = ppm (read from the curve) X 500 X DF. NOTE: The
500 is obtained from the following equation: 500 (25 ml extracting solution/
5 g sample) X (100 ml final volume/1 ml extract).
6. pp2m of element in the soil = (ppm of element in the soil) X 2.
3.2.13 Organic Carbon by Walkley-Black Method
3.2.13.1 Principle—
The method involves the oxidation of organic carbon by an oxidizing
agent, potassium dichromate. The reaction is aided by the addition
of sulfuric acid which generates heat. After the reaction is complete,
the remaining dichromate is determined by titration with standard ferrous
sulfate solution. From the amount of dichromate reduced, the amount of
oxidized organic carbon can be calculated (Allison, 1965; Jackson, 1958).
3.2.13.2 Comments—
Some interference can result from chlorides, higher oxides of manganese
and reduced iron. With the use of proper precautions, this interference
can be eliminated or greatly reduced (Walkley, 19^7; Jackson, 1958). Ferrous
iron and chlorides tend to give positive or high organic carbon values,
whereas, oxides of manganese tend to give negative or low values (Allison,
1965).
All samples should be ground in a porcelain or agate mortar. Iron or steel
mortar is avoided because of the introduction of reducing material in the
form of metallic iron.
3.2.13.3 Chemicals' —
1. Potassium dichromate (K2Cr20y), 1 N_: Dissolve 1*9.0^ g K^CrgOy (dried
at 105°C) in distilled water and dilute to a volume of 1 liter.
2. Sulfuric acid (H2SOlt), concentrated.
3. Ferroin solution, 0.025 M (available from Fisher Scientific Company)
k. Ferrous sulfate (FeSO^-^O) , 0.5 N.: Dissolve lUO.O g of FeSOi^7H20
in distilled water. Add 15 ml of concentrated ^SO^ and allow to cool.
Dilute to 1 liter with distilled water. Standardize reagent daily by
titrating it against 10 ml of 1 N
3.2.13.1* Materials—
1. Porcelain or agate mortar and pestle.
78
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2. Flasks, 500 ml, Erlenmeyer, wide-mouth.
3. Pipet, 10 ml.
U. Pipet, 20 ml.
5. Buret, 50 ml
6. Balance, can be read to 0.001 g.
7. Sieve, 0.25 mm (60 mesh) openings, nonferrous.
8. Buchner funnel.
9. Filter paper, (Whatman ^0 or equivalent).
10. Weighing pans.
3.2.13.5 Procedure —
1. Grind air-dry samples to pass 60 mesh sieve with a porcelain or agate
mortar.
2. Weigh and record tare weights of two clean and dry weighing pans.
3. In previously tared weighing pans, weigh 2.00 g (0.50 g of Horizon 1
and carbolith material) air-dry soil samples. NOTE: One sample is used
for the procedure. The second sample is placed in an oven at 105°C for
16 hours, allowed to cool in a desiccator, and its oven-dry weight recorded.
(See 3.2.13.6. No. 3).
U. Place weighted air-dry sample in a 500 ml Erlenmeyer flask.
5. Pipet exactly 10 ml of 1 N_ I^C^O., solution into the soil. Swirl flask
gently until mixed.
6. Rapidly pipet 20 ml of concentrated I^SOip directing the stream into
the suspension. Mix "by gentle rotation for 1 minute to insure complete
contact of reagent with sample. NOTE: Avoid throwing soil up onto the
sides of the flask and out of contact with the reagent.
7. Allow mixture to stand on an asbestos sheet for 30 minutes.
8. Dilute to 200 ml with distilled and deionized water.
9. Add k drops to 0.025 M Ferroin indicator.
10. Back titrate with 0.5 N_ ferrous sulfate solution from a buret. As the
endpoint is approached, the solution has a greenish cast which changes to
dark green. At this point, add ferrous sulfate drop by drop until the
color changes sharply from blue to red (maroon color in reflected light
against a white background). CAUTION: Discard and rerun with less soil
79
-------
if 8 ml or more of the dichromate is reduced. If the endpoint cannot be
clearly distinguished as described above, rerun sample and filter suspen-
sion using a buchner funnel before doing steps 9 and 10.
3.2.13.6 Calculations —
1. meq K2Cr2Oy = (ml K^C^Oy used) X (N
2. meq FeSOl^ = (ml FeSO^ used) X (N
3. Oven-dry weight of sample = (wt. oven-dry sample and tared pan) -
(wt. of tared pan).
k. % organic carbon = [(meq K^C^Oy - meq FeSO^) X (0.003 X 100 X 1.33)]/
Oven dry sample wt.
3.2. Ik Organic Carbon Determination By Low Temperature Ignition
3.2.1^.1 Principle —
Water and hydroxides are driven off the sample by heating to 105°C.
Organic matter is oxidized by heating at itOO°C for 7 hours. The percent
organic matter can be determined by weight loss.
3.2.1U.2 Comments—
Mineral matter is assumed to be unchanged at the UOO°C temperature range.
For soils containing amorphous materials, the discrimination between organic
and mineral matter is far from complete (Jackson, 1958).
3.2.1*1.3 Chemicals —
None required.
3.2.lk.k Materials—
1. Muffle furnace.
2. Drying oven.
3. Desiccator with drierite desiccant.
U. Balance, can be read to 0.01 g.
5. Crucibles or evaporating dishes.
3.2.li)..5 Procedure (Modified from Jackson, 1958) —
1. Weigh a clean and dry crucible. Record tare weight (A).
2. Weigh 10.00 g of less than 60 mesh sample in tared crucible.
80
-------
3. Place in oven and heat for h hours at 105°C.
k. Remove sample and allow to cool in desiccator.
5. Weigh sample. Record weight (B).
6. Place sample in oven and heat for 7 hours at i|-000C.
7. Remove sample and allow to cool in desiccator.
8. Weigh sample. Record weight (C).
3.2.1U.6 Calculations
1. Legend:
A = Tare weight of crucible.
B = Weight of sample and crucible after heating k hours at 105°C.
C = Weight of sample and crucible after heating 7 hours at UOO°C.
D = Weight of sample after heating k hours at 105°C.
E = Weight of sample after heating 7 hours at 400°C.
2. D = B - A.
3. E = C - A.
^. Organic matter oxidized by heating = D - E.
5. % organic matter in sample = (Organic matter oxidized by heating/D)
X 100.
3.2.1$ Total Nitrogen by Kjeldahl Method
3.2.15.1 Principle—
In the Kjeldahl procedure, nitrogen is converted to ammonium ion by oxidation
with concentrated sulfuric acid. With the addition of a catalyst such as
copper, selenium, or mercury, this oxidation, which normally progresses very
slowly, can be accelerated. Raising the boiling point by the addition of
such salts as sodium sulfate or potassium sulfate also accelerates the
reaction.
The ammonium ion produced by this oxidation is determined by making the
solution strongly alkaline with sodium hydroxide, the liberated ammonia is
distilled into a boric acid solution. The resulting ammonium borate is back
titrated to boric acid with a standard acid (Bremner, 1965; Winkler, 1913).
81
-------
3.2.15.2 Comments
Continuous boiling of the concentrated sulfuric acid, and Kel-pak mixture
for several hours requires insulation and venting of the system so the
sulfuric acid condenses about one-third of the way up the digestion flask
neck.
Materials adhering to the walls must be dislodged and brought into contact
with the acid by rotation of the flask. Clay soils are particularly trouble-
some because clay promotes splattering. With the addition of glass beads,
bumping during digestion can usually be eliminated. Optimum digestion
temperature is between 360 and ^00°C. Loss of nitrogen may occur if heated
above UlO°C.
3. 2.1$. 3 Chemicals—
1. Kel-pak powder No. 3 (HgO + KgSO^) (available from Matheson Scientific
Co.).
2. Sulfuric acid (l^SO^), concentrated.
3. Sulfuric acid (l^SCk), dilute (approximately 0.1 IT) : Dilute kk.Q ml of
concentrate ISO to 16 liters with distilled water.
k. Sodium hydroxide (NaOH), k5% with sodium thiosulfate (^28203-
Under a fume hood in a rubber bucket mix U5^5.9 g of NaOH flakes (for
nitrogen determination) with 438.0 g of Na2S20g'5H20. Dissolve and dilute
to 11.355 liters (3 gal) with carbon- dioxide-free water (See 3.2.2.2 No. l).
Cool overnight and siphon into dispensing apparatus. Protect from COo in
the air with soda lime or ascarite in a guard tube.
5. Boric acid (113:603), k%: Dissolve 720.0 g of H3B03 in distilled and
deionized water on a hot plate. Dilute to 18 liters with distilled and
deionized water. Add 60 ml of Bromocresol green-methyl red indicator (see
below ) .
6. Bromocresol green-methyl red indicator: Mix 0.5 g of bromocresol green
and 0.2 g methyl red with 100 ml of ethyl alcohol (90/0 . Adjust to medium
color (brown) with a few drops of weak NaOH.
7. Zinc (Zn), granular.
3.2.15.U Materials—
1. Kjeldahl electric digestion manifold
2. Kjeldahl electric distillation rack.
3. Room equipped with exhaust fan.
1*. Flasks, Kjeldahl, 800 ml.
82
-------
5. Flasks, Erlenmeyer, widemouth, 500 ml, marked at 230 ml.
6. Sieve, 20 mesh.
T. Balance, can "be read to 0.1 g.
8. Asbestos gloves.
3.2.15.3 Procedure—
1. Place 10 g unground sample (sieved to 20 mesh.) wrapped in filter paper
in Kjeldahl flask. Also prepare two blanks without soil, but containing
filter paper.
2. Add 2 packets of Ho. 3 Kel-pak.
3. Turn on exhaust fan.
h. Add kO ml concentrated I^SO^. NOTE: While rotating flask, run acid down
side to carry down sample.
5. Mix contents by gentle swirling and place flask carefully on Kjeldahl
rack.
6. When all flasks are in place, set all knobs so that a moderate boiling
and digestion of the sample can be seen.
7. After 30 minutes increase heat to a rapid boil for 30 minutes so that
sulfur dioxide can be released and to insure complete digestion of the
sample.
8. Rotate flasks l80° and continue heating until all the black organic
matter is digested (usually about 1 hour).
9. Allow sample to cool on digestion rack and stopper. "CAUTION. Do not
place stopper in hot flask as it may implode upon cooling.
10. Let stand until solution reaches room temperature and cautiously add
300 ml distilled water to each flask. NOTE: Rotate flasks while pouring
to wash neck.
11. Swirl flasks gently to dissolve crystals.
12. Add lA teaspoon granular zinc to each flask.
13. Pour 30 ml 113603 (h% containing indicator) into 500 ml wide mouth
Erlenmeyer flasks. NOTE: One required for each sample and blank and
numbered to correspond to each Kjeldahl flask.
lh. Place Erlenmeyer flasks on Kjeldahl distillation rack. NOTE: Top of
glass delivery tube must be below surface of 113603.
83
-------
15. Turn condenser water switch to manual. After 30 minutes turn water
switch to automatic if unit is so equipped.
16. Add 133 ml NaOH (U5#) slowly to each Kjeldahl flask. NOTE: Allow NaOH
to run down side of flask so that it lies on the bottom.
17. Place each flask on Kjeldahl distillation rack as NaOH is added, using
steps 18-21.
18. Wet hands with distilled water and apply water to rubber stoppers.
19. Place stopper securely in flask. Set flask on burner.
20. As soon as flask is in position, turn burner switch to make a moderate
boil but not enough to cause solution to boil into flask neck.
21. Swirl flask to mix NaOH layer with the rest of the sample solution and
set back in position making sure stopper is tight.
22. When 200 ml has distilled into receiving flask, set receiving flask
(Erlenmeyer) down and turn off heat. CAUTION: Be sure to set flask down
before turning off heat or distillate may suck back through condensers.
NOTE: Distillate color should be green or dark blue.
23. Wash delivery tube with a small stream of distilled water from a wash
bottle before removing receiving flask.
2k. When cool, titrate distillate with 0.1 N_ ^SOij until solution becomes
clear and then turns pink.
25. Record reading.
3.2.1^.6 Calculations—
1. Average of sample blanks = [reading (blank l) + reading (blank 2)]/2.
2. Corrected sample reading = (sample reading) - (average of sample blanks).
3. Constant = (N_ acid) X (meq. wt. of N) X (100) X (l/wt. of sample); where
1J acid = 0.1, meq. wt. of nitrogen = O.OlU, and 100 changes constant to
percent.
The equation can then be written:
Constant = (O.l) X (O.OlU) X (.100) X (l/wt. of sample), which can be
simplified to:
Constant = (0.1*0 X (l/wt. of sample).
k. % nitrogen = (corrected sample reading) X constant.
84
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3.2.16 Calcium Saturation Cation Exchange Capacity
3.2.16.1 Princ role—
Cation exchange capacity (CEC) is defined as the sum of the exchangeable
cations in a soil. Several methods are used for determining the CEC of a
soil.
In this method, a solution of calcium chloride is used to saturate the
soil exchange complex and remove all other exchangeable cations from the
exchange sites. Calcium is then removed from the exchange complex by
saturating the soil with magnesium acetate. By determining the amount of
calcium in the magnesium acetate extract, the CEC of the soil can be measured.
3.2.16.2 Comments —
Soils with a pH greater than 5.5 or surface soils less than pH 5.5 which
have been treated with lime must be pretreated with 1.0 1J sodium acetate
(pH 5.0) to move free carbonates (Jackson, 1958 pp. 62-63). To avoid this
pretreatment, sodium saturated CEC (see 3.2.17) can be used.
Since calcium chloride is used to saturate the soil instead of a buffered
acetate, the pH of the soil is not affected and the CEC is determined at
the actual pH of the soil. This is important because it is well known that
as pH rises the CEC increases (Coleman and Thomas, 1967).
3.2.16.3 Chemicals—
1. Calcium chloride (CaCl2«2H20), 1 N_: Dissolve 1*»7.03 g CaCl2«2H20 and
dilute to 1 liter with distilled water.
2. Methanol (CH3OH), 95$: Dilute 950 ml of methanol with 50 ml distilled
water.
3. Magnesium acetate (Mg(OAc)2), 1 N_: Dissolve 107.25 g of Mg(OAc)2 and
dilute to 1 liter with distilled and deionized water.
k. Calcium atomic absorption standard (1000 ppm).
5. Calcium (Ca) standard stock solution (100 ppm): Pipet 10 ml of calcium
atomic absorption standard (1000 ppm) in a 100 ml volumetric flask. Bring
to volume with deionized water. Make fresh daily.
6. Silver nitrate (AgN03), 0.1$: Dissolve 0.10 g of AgN03 and dilute to
100 ml with distilled water. Store in brown bottle.
7. Lanthanum chloride (LaCl3'6H20), 5%: Dissolve 127 g of LaCl3«6H20 with
deionized water and make to a volume of 1 liter.
3.2.16.4 Materials—
1. Balance, can be read to 0.0001 g.
85
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2. Centrifuge tubes, 100 ml.
3. Rubber stoppers (to fit centrifuge tubes).
k. Shaker, horizontal reciprocating type, 6.35 cm (2.5 in) stroke, 120
strokes per minute.
5. Centrifuge (international Equipment Company Model K with No. 279 head or
equivalent centrifuge and 12-place head).
6. Graduated cylinder, 100 ml.
T. Beaker, 100 ml.
8. Dropper bottle.
9. Bottle, polyethylene, 100 ml (one needed per sample).
10. Atomic Absorption unit (Perkin-Elmer Model ^03 or equivalent).
11. Flasks, volumetric, 100 ml (7 required for standards).
12. Desiccator with drierite drying agent.
3.2.16.5 Procedure (Modified from Rich, 196l)—
1. Weigh 5 g of less than 60 mesh soil into a 100 ml centrifuge tube.
2. Add 50 ml of 1 K CaCl2.
3. Stopper centrifuge tube and shake horizontally for ^5 minutes on a
reciprocating shaker insuring that the solid material in the bottom of the
tube is completely dispersed.
U. Remove stopper and centrifuge suspension until clear (at least 5 minutes
at 2000 RPM).
5. Pour off clear solution.
6. Repeat steps 2 through 5 two more times.
7. Add 50 ml of distilled water to the soil in the centrifuge tube.
8. Stopper and shake horizontally for 15 minutes on a reciprocating shaker
insuring that the solid material in the bottom of the tube is completely
dispersed.
9. Remove stopper and centrifuge for at least 5 minutes at 2000 RPM. Pour
off clear solution.
10. Repeat steps 7 through 9 one more time.
86
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11. Add 50 ml of 95% methanol to the soil in the centrifuge tube.
12. Stopper and shake horizontally for 15 minutes on a reciprocating shaker
insuring that the solid material in the bottom of the tube is completely
dispersed.
13. Remove stopper and centrifuge for at least 5 minutes at 2000 RPM.
1^. Repeat steps 11 through 13 one more time.
15. Repeat steps 11 through lU, but pour clear solution into a 100 ml beaker.
16. Add a few drops of 0.1$ AgN03 to the solution in the beaker. NOTE:
If no precipitations occur, no further washing with methanol is required.
If precipitation occurs, repeat steps 15 through 16 until no precipitation
occurs.
IT. Dry soil in the centrifuge tube in a drierite desiccator.
18. Weigh 0.5000 g dry, Ca-saturated soil into a 100 ml centrifuge tube.
19. Add 50 ml of 1 N Mg(OAc)2.
20. Stopper and shake horizontally for l6 hours on a reciprocating
shaker.
21. Remove stopper and centrifuge suspension until clear (for at least
5 minutes at 2000 RPM).
22. Pour solution into a 100 ml polyethylene bottle. Add 1.0 ml of
5% LaCl3«6H20 and cap bottle. NOTE: This solution will be used for
Ca determination by atomic absorption.
23. Prepare CEC determination standards from Table 7.
2k. Aspirate the standards on the atomic absorption unit following
the instruction manual of instrument.
25. Make a standard curve plotting ppm of calcium on the horizontal
axis and instrument reading on vertical axis.
26. Analyze samples for calcium and determine ppm of calcium from the
prepared curve. NOTE: If unknown does not fall within the range of
the standard curve, dilute sample with 1 N_Mg(OAc)o and add 5$ LaCl^-
but not exceeding 1$ La in the final dilution. The dilution factor is
obtained by taking the final volume and dividing it by the initial aliquot.
3.2.16.6 Calculations—
1. Legend:
A = ppm of calcium as read from standard curve.
87
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TABLE 7. STANDARDS FOR CALCIUM CEC DETERMINATION
Flask
No.
(100 ml)
1
2
3
U
5
6
7
ml of Ca
stock solution
(100 ppm)
0.0
1.0
2.0
U.O
6.0
8.0
10.0
ml of
Mg(OAc)2
(IN)
98.0
97-0
96.0
9^.0
92.0
90.0
88.0
ml of
LaClo'6H20
/C«M
\5fl)
2.0
2.0
2.0
2.0
2.0
2.0
2.0
Represented
Ca
(ppm)
0
1
2
U
6
8
10
DF = dilution factor, which is 1 if no dilution was necessary to read
within the range of the standard curve. The dilution factor is obtained
by taking the final volume and dividing it by the initial aliquot.
2. CEC (meq/100 g) = (A) X (DF) X (0.5l), where the 0.51 is derived from
the equation: (ppm/1,000,000) X (volume extracting solution/sample wt.) X
(1000 meq per eq/eq. wt of Ca) X 100 g basis. NOTE: The volume of the
extracting solution = 50 ml extracting solution + 1 ml LaCl2*6H20 = 51 ml.
3.2.17 Sodium Saturation Cation Exchange Capacity
3.2.17.1 Principle—
In this method, the soil is saturated with a solution of sodium acetate
to replace all other exchangeable cations on the exchange sites with sodium.
Sodium is then removed from the exchange complex by saturating the soil
with an ammonium acetate solution. CEC is measured by determining the
amount of sodium in the ammonium acetate extract.
3.2.17.2 Comments—
This method is used for both calcareous and noncalcareous soils. In mine-
soils, it is recommended that the sodium acetate method for determining CEC
be used. Minesoils with a pH as low as 5.5 can contain free carbonates
which interfere with the CEC determination by calcium saturation.
Cation exchange capacity may also be determined using ammonium acetate as
a saturating solution; however, because of variable amounts of calcium
88
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carbonate and gypsum present in minesoils and their solubility in ammonium
acetate, it is recommended that either sodium acetate or calcium chloride
saturation be used for determining CEC. Solubility of calcium carbonate
in 1 N_ sodium acetate at pH 8.2 is much lower than it is in neutral 1 N_
ammonium acetate.
Interferences occur in the sodium determination with some atomic absorption
units. This interference can usually be corrected by the addition of 2,000
ppm of potassium to both the standards and the unknowns.
3.2. IT. 3 Chemicals—
1. Sodium acetate (NaOAc), 1.0 N_: Dissolve 136 g of NaOAc in distilled
water and dilute to 1 liter. NOTE: The pH of this solution should be 8.2.
If needed, add a few drops of acetic acid or KaOH solution to adjust the
pH to 8.2.
2. Ammonium acetate (NH^OAc), 1.0 N_: Dilute ll^t ml of glacial acetic
acid (99-5$) with distilled water to a volume of approximately 1 liter.
Then carefully add 138 ml of concentrated ammonium hydroxide (iffl^OH) and
slowly add distilled water to obtain a. volume of approximately 1980 ml.
Check the pH of the solution and add more NHl^OH as needed to obtain a pH
of 7.0. Dilute the solution to a volume of 2 liters with distilled water.
3. Isopropyl alcohol, 99$.
U. Potassium stock solution, 10,000 ppm: Dissolve 19-07 g of potassium
chloride (KCl) in 1 liter of deionized water.
5. Standard sodium solution, 1000 ppm, atomic absorption spectroscopy grade.
3.2.17.1* Materials—
1. Centrifuge tubes, 50 ml, round bottom polypropylene.
2. Rubber stoppers (to fit centrifuge tubes).
3. Shaker, horizontal reciprocating type, 6.35 cm (2.5 in.) stroke,
120 strokes per minute.
It. Centrifuge (international Equipment Company Model K with No. 279 head
or equivalent centrifuge and 12-place head).
5. Volumetric flasks, 100 ml.
6. Atomic absorption spectrophotometer (Perkin-Elmer model *t03 or
equivalent).
7. Balance, can be read to 0.01 g.
89
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3.2.IT.5 Procedure—
1. Weigh U.O g of less than 60 mesh material and transfer to 50 ml
centrifuge tube. NOTE: If the material is very coarse textured (loamy
sand or sand), a 6.0 g sample is used.
2. Record weight of sample (A).
3. Add 33 ml of 1.0 N_NaOAc solution to the centrifuge tube.
k. Stopper the tube and shake in a reciprocating shaker at 120 strokes per
minute for 5 minutes insuring that the solid material in the bottom of the
tube is completely dispersed.
5. Unstopper the tube and centrifuge until the supernatant liquid is
clear (at least 5 minutes at 2000 RPM). Decant and discard the liquid.
6. Repeat steps 3 through 5 three more times.
7. Add 33 ml of 99% isoproply alcohol to centrifuge tube.
8. Stopper tube and shake on reciprocating shaker for 5 minutes insuring
that the solid material in the bottom of the tube is completely dispersed.
9. Unstopper centrifuge tube and centrifuge it until the supernatant
liquid is clear (at least 5 minutes at 2000 RPM). Then decant and discard
the liquid.
10. Repeat steps 7 through 9 two more times.
11. Add 33 ml of 1 N. NH^OAc to centrifuge tube, stopper tube and shake
for 5 minutes insuring that the solid material in the bottom of the tube
is completely dispersed.
12. Unstopper tube and centrifuge until supernatant liquid is clear (at
least 5 minutes at 2000 RPM).
13. Decant liquid into a 100 ml volumetric flask.
lit. Repeat steps 11 through 13 two more times.
15. Fill the volumetric flask to the 100 ml mark using the IN NH^OAc
solution.
16. Take 10 clean 100 ml volumetric falsks and label them 0, 5» 10, 20,
30, 40, 50, 60, 70, and 80 ppm sodium.
17. Pipet 0.5 ml of the 100 ppm sodium standard into the flask labeled
5 ppm sodium. Into the flasks labeled 10 through 80 ppm, pipet 1 ml through
8 ml, respectively, of the 1000 ppm sodium standard solution.
90
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18. Dilute all flasks to volume with 1 H_ NH^OA solution. NOTE: The flask
labeled 0 ppm will contain only the 1 N NH^OAc extracting solution.
19. Turn on the atomic absorption unit and wet it for emission mode.
Read instruction manual carefully and set all operating parameters according
to the instrument instruction manual.
20. After the atomic absorption unit is ready, zero the instrument using
the 1 N_ ammonium acetate extracting solution, not distilled water. Aspirate
standards and record readings.
21. Plot a standard curve using ppm sodium on the horizontal axis and the
instrument readings on the vertical axis.
22. Record the instrument readings for all unknowns and read the concentra-
tion (B) of sodium from the standard curve. NOTE: If the unknown does
not fall within the range of the standard curve which you have plotted,
dilute the unknown with NH^OAc and potassium stock solution using 2 ml of
the potassium stock solution for every 10 ml of NE^OAc. Then measure the
amount of sodium present.
3.2.17.6 Calculations—
1. Legend:
A = Sample weight.
B = ppm of sodium as read from the standard curve.
DF = dilution "factor, which is 1 or unity if no dilution of the unknown had
to be made to get it to read within the range of the standard curve.
2. CEC (meq./100g) =
(B/1,000,000) X (DF) X (Vol. extracting solution/sample wt.) X (1000 meq/
eq. wt Na) X lOQg,
Where:
Vol. extracting solution = 100 ml
eq. wt of Na = 23.
The above equation can be reduced to:
CEC (meq/lOOg) = (B X DF X 10) / (23 X A).
3.2.18 Electrical Conductance of Soil Extract
3.2.18.1 Principle—
Pure water (water which contains no dissolved substances) is not a good
91
-------
conductor of an electrical current. Water becomes a better electric current
conductor with the addition of dissolved salts. The amount of electric
current conducted through this water is approximately proportional to the
amount of salts dissolved in the water. Based on this fact, a measurement
of the amount of electric current that is conducted by a soil extract will
provide information as to the amount of salts present in the soil. This
simple measurement provides an accurate indication of the concentration of
ionized constitutents in the soil extract. The electrical conductivity
of a soil extract is closely related to the sum of cations (or anions) as
determined chemically. This measurement usually correlates closely with
the total dissolved solids.
3.2.18.2 Comments—
Extracts to be used for electrical conductivity measurements should be
taken from a saturated soil paste. Measuring the salt concentration of
an extract obtained at the field moisture state would be an ideal method;
however, it is much easier to obtain a soil extract from a saturated paste.
This is extremely important when doing electrical conductivity measure-
ments on a routine basis.
When making a saturated soil paste, some practice is necessary to obtain
consistent results. Dried peat or muck usually require an overnight wetting
period to obtain a satisfactory saturated paste. Add water to fine textured
soils without stirring and allow the sample to wet slowly. This will enable
the fine textured material to reach saturation without puddling occurring.
Care must be taken not to overwet coarse textured soils. If water stands
on the surface, the soil has been over saturated and a small additional
amount of soil must be added.
The soil material used for electrical conductivity measurements should not
be oven dried. Material should be air dried and ground to pass a 60 mesh
sieve (see 3.1.2).
3.2.18.3 Chemicals—
1. Distilled water.
2. Potassium chloride (KCl), 0.01 II: Dissolve 0.7^56 g of KC1 in distilled
water, and dilute with distilled water to 1 liter. This is the standard
reference solution and at 25°C it has an electrical conductivity to O.OOlUl
mho/cm.
3. Sodium metaphosphate ((NaK>3)g), 0.1$: Dissolve 0.1 g of (NaP03)g
(Fisher Scientific #S-333) in distilled water and dilute to 100 ml.
3.2.18. ^ Materials—
1. Wheatstone bridge, alternating-current type, suitable for conductivity
measurements, (industrial Instruments Incorporated Model RC-16B2 or
equivalent).
92
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2. Conductivity cell, pipette-type, with platinized platinum electrodes.
The cell constant should be approximately 1.0 reciprocal centimeter.
3. Flask, volumetric, 1000 ml.
h. Balance, can be read to 0.01 g.
5. Aluminum can with lid (large enough to contain sample).
6. Spatula.
7. Aluminum weighing pan.
8. Drying oven.
9. Dessicator, with silica gel dessicant.
10. Buchner type filtering funnel, 11 cm inside diameter.
11. Filter flask.
12. Filter paper (Whatman k2 or equivalent).
13. Vacuum source.
N *
lU. Graduated cylinder, 100 ml volume.
15. Pipette, measuring, 10 ml capacity.
3.2.18.3 Procedure (modified from U.S. Salinity Laboratory Staff, 195*0—
1. Weigh UOO g of air-dried soil. Transfer the soil to an aluminum
can (with lid).
2. Add water to the sample in small increments by pouring the water down
the side of the can. Water is added to the sample in this fashion until
the saturation point of the soil is almost reached.
NOTE: Do not stir soil sample while adding water. Since water movement
through puddled soil is very slow, the soil is allowed to wet by capillarity
and then mixed to ensure against puddling.
3. Stir the wetted soil with a spatula until a condition of saturation
is reached. Small amounts of water may be added while mixing to insure
that the saturation point has been reached. NOTE: At saturation the soil
paste glistens as it reflects light and the mixture slides off of the
spatula easily.
k. After the mixing has been completed, place the lid on the aluminum
can and let sample stand for 1 hour or more.
93
-------
5. After sample has set for the required amount of time, check sample
for saturation. NOTE: If the paste has stiffened or lost its glisten,
add more water and mix it again. On the other hand, if free water has
collected on the surface of the paste, add additional air-dry soil to
absorb free water and remix the sample.
6. After a saturated paste has been obtained, remove a teaspoon-full
of the saturated paste for oven-drying and replace lid. Allow the saturated
soil paste to stand at least k hours.
7. Weigh an oven-dry aluminum weighing pan to the nearest 0.01 g.
Record weight (A).
8. Place subsample of the saturated soil paste (from step 6) in aluminum
weighing pan. Weigh pan and sample to the nearest 0.01 g. Record weight (B).
9. Place weighing pan and sample in an oven at 105°C for 16 hours (or
overnight). Remove from oven and cool in a dessicator.
10. Weigh oven-dry sample and pan. Record weight (C).
11. After the saturated soil paste has stood for at least k hours (from
step 6), transfer it to a Buchner funnel fitted with one sheet of Whatman #1*2
(or equivalent) filter paper.
12. Attach filter flask to vacuum source, apply vacuum, and collect
filtrate. Terminate filtration when air begins to pass through the filter.
NOTE: Refilter if filtrate is turbid.
13. Add one drop of 0.1$ sodium hexametaphosphate solution for each
25 ml of extract.
Ik. Allow the standard 0.01 N_ KC1 solution and the sample of the soil-
water extract to adjust to room temperature. NOTE: As long as the tem-
perature of the room is within the range of 20-30°C, the absolute temperature
of the solutions are not important. However, it is extremely important
that the standard solution and the extract be at the same temperature. If
greater precision is required bring the standard solution and soil-water
extracts to a temperature of 25°C in a constant temperature bath.
15. Turn on Wheatstone bridge and allow instrument to warm up.
16. When instrument is ready, rinse and fill the conductivity cell with
the standard 0.01 W_ KC1 solution.
17. Balance the wheatstone bridge according to the instruction manual
provided by the manufacturer. Record the cell resistance (D) in ohms.
18. Rinse and fill the cell with the soil-water extract. NOTE: If the
volume of the extract is limited, rinse the cell with distilled water
followed by acetone. Dry the cell by drawing air through it until the
acetone has evaporated. Allow the cell to come to room temperature.
94
-------
19. Balance the bridge and record the cell resistance (E) in ohms.
3.2.18.6 Calculations —
1. Legend:
A = Weight of oven-dry weighing pan.
B = Weight of saturated soil and weighing pan.
C = Weight of oven-dry soil and weighing pan.
D = Initial cell resistance.
F = Final cell resistance.
2. % Moisture of sample at saturation = [(B-C)/(C-A) ] X 100.
3. Electrical conductivity (EC) mmhos/cm, at 25°C = [(0.0014118 X D)/F].
h. Total cation concentration, meg/liter = 10 X (EC).
3.2.19 Sodium- Absorption-Ratio
3 . 2 . 19 . 1 Princ iple —
Plants growing in saline soils are affected by the salt concentrated in the
soil solution. The principle cations present are calcium, magnesium, and
sodium with small amounts of potassium. If the proportion of sodium is
high, the alkali hazard is high. By making a soil-water extract and
measuring the salt concentration of the extract, the salinity hazard of
the soil can be determined.
3. 2 . 19 . 2 Comment s —
Lanthanum chloride must be added to both the standards and the extract to
eliminate interferences in determining calcium and magnesium by atomic
absorption. Interferences may also occur in the sodium determination and
should be corrected by the addition of an excess (1000-2000 ppm) of
potassium or lithium to both the standards and samples (see manuals supplied
with atomic absorption unit ) .
3.2.19.3 Chemicals—
1. Calcium atomic absorption standard (1000 ppm).
2. Magnesium atomic absorption standard (1000 ppm).
3. Sodium atomic absorption standard (1000 ppm).
k. Lanthanum chloride (LaCl^-gO) , 5$: Dissolve 127 g of
with deionized water and bring to a volume of 1 liter.
95
-------
5. Sodium metaphosphate ((NaPC^g), 0.1$: Dissolve 0.1 g of
(Fisher Scientific No. S-333) in distilled water and dilute to 100
3.2.19.H Materials—
1. Atomic absorption spectrophotometer (Perkin-Elmer Model U03 or
equivalent).
2. Flasks, volumetric, 100 ml.
3. Pipet, 1 ml.
^. Balance, can be read to 0.01 g.
5. Aluminum can with lid (large anough to contain sample).
6. Spatula.
J. Weighing pan.
8. Drying oven.
9. Desiccator.
10. Buchner filter funnel.
11. Filter paper (Whatman h2 or equivalent)
12. Vacuum source pulling a constant vacuum.
13. Bottle (to collect filtrate).
3.2.19.5 Procedure (modified from Bower and Wilcox, 1965; U.S. Salinity
Laboratory Staff, 195*0—
1. Weight UOO g of air-dry soil. Transfer soil to an aluminum can
(with lid).
2. Add water to the sample in small increments by pouring the water down
the side of the can. Water is added to the sample in this fashion until
the saturation point of the soil is almost reached. NOTE: Do not stir
sample while adding water. Since water movement through puddled soil is
very slow, the soil is allowed to wet by capillarity and then mixed to
insure against puddling.
3. Stir the wetted soil with a spatula until a condition of saturation is
reached. Small amounts of water may be added while mixing to insure that
the saturation point has been reached. NOTE: At saturation the soil
paste glistens as it reflects light and the mixture slides off of the
spatula easily.
96
-------
k. After the mixing has been completed, place the lid on the aluminum
can and let stand for at least 1 hour.
5. After sample has set for the required amount of time, check sample
for saturation. NOTE: If the paste has stiffened or lost its glisten,
add more water and remix. If free water has collected on the surface,
add additional air-dry soil to absorb the free water and remix.
6. After a saturation paste has been obtained, remove a teaspoonful of
the saturated paste for oven-drying and replace lid. Allow the saturated
soil paste to stand at least k hours.
7. Weigh an oven-dry aluminum weighing pan to the nearest 0.01 g.
Record weight (A) .
8. Place subsample of saturated soil paste (from step 6) in aluminum
weighing pan. Weigh pan and sample to the nearest 0.01 g. Record weight
(B).
9. Place weighing pan and sample .in an oven at 105°C for 16 hours.
Remove from oven and cool in dessicator.
10. Weigh oven-dry sample and pan. Record weight (C).
11. After the saturated soil paste has stood for at least k hours (from
step 6), transfer it to a Buchner funnel fitted with one sheet of Whatman
No. 1*2 (or equivalent) filter paper.
12. Attach filter flask to vacuum source, apply vacuum, and collect
filtrate. Terminate filtration when air begins to pass through the filter.
NOTE: Ref ilter if filtrate is turbid.
13. Add one drop of 0.1$ sodium hexametaphosphate solution for each
25 ml of extract.
Ik. Take 10 clean 100 ml volumetric flasks and label them 0, 5, 10, 20,
30, 1+0, 50, 60, 70, and 80 ppm sodium.
15. Pipet 0.5 ml of 1000 ppm sodium standard into the flask labeled 5
sodium. Into the flasks labeled 10 through 80 ppm, pipet 1 through 8 ml,
respectively, of the 1000 ppm sodium standard solution.
l6. Dilute all flasks to volume with deionized water. NOTE: The
flasked labeled 0 ppm will contain only deionized water.
17. Turn on the atomic absorption unit and set it for emission mode.
Read instrument instructions manual carefully and do all settings
accordingly.
18. After the atomic absorption unit is ready, zero the instrument using
the 0 ppm standard. Record the reading for each of the other standards.
97
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19. Plot standard curve -using ppm sodium on the horizontal axis and
instrument reading on the vertical axis.
20. Measure the amount of sodium present in the unknowns. NOTE: If the
unknown does not fall within the range of the standard curve, dilute with
deionized water and remeasure the amount of sodium present. Record the
dilution factor (DF). The dilution factor is obtained by taking the final
volume and dividing it by the initial aliquot.
21. For each 100 ml of extract, or part thereof, of the volume found in
step 13, add 2 ml of 5$ LaCl3'6H20.
22. Prepare calcium and magnesium standards as shown in Table 8 using
100 ml volumetric flasks.
23. Set atomic absorption unit to absorption setting according to the
instruments instruction manual.
2k. After the atomic absorption unit is ready, zero the instrument using
the 0 ppm standard (flask no. l). Record the reading for each of the other
standards.
25. Plot standard curves using ppm of element on the horizontal axis and
instrument reading on the vertical axis.
26. Measure the amount of calcium and magnesium present in the unknowns.
NOTE: If the unknown does not fall within the range of the standard curve,
dilute with deionized water and add 5% LaClg^I^O, but not to exceed 1%
La in the final dilution. Remeasure the amount of calcium and magnesium
present and record the dilution factor. The dilution factor is obtained by
taking the final volume and dividing it by the initial aliquot.
3.2.19.6 Calculations—
1. Legend:
A = Weight of oven-dry weighing pan.
B = Weight of saturated soil and paste and weighing pan.
C = Weight of oven-dry soil paste and weighing pan.
2. Meq/1 of Na = ppm of Na (read from curve)/23.00, where 23.00 is the
equivalent weight of sodium.
3. Meq/1 of Ca = ppm of Ca (read from curve)/20.0l», where 20. Qk is the
equivalent weight of calcium.
h. Meq/1 of Mg = ppm of Mg (read from curve)/12.l6, where 12.16 is the
equivalent weight of magnesium.
98
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TABLE 8. CALCIUM AND MAGNESIUM STANDARDS FOR SODIUM-ADSORPTION RATIO
Flask
No.
1
2
3
k
5
6
7
Calcium stock
solution
(100 ppm)
(ml)
0.0
1.0
2.0
H.O
6.0
8.0
10.0
Magnesium stock
solution
(10 ppm)
(ml)
0.0
2.0
lt.0
6.0
8.0
10.0
15.0
LaClo'6HpO
(5*)
(ml)
2.0
2.0
2.0
2.0
2.0
2.0
2.0
Deionized Represents
water
(ml)
98.0
95.0
92.0
88.0
8U. 0
80.0
73. 0
ppm
Ca
0.0
1.0
2.0
k.o-
6.0
8.0
10.0
Mg
0.0
0.2
O.U
0.6
0.8
1.0
1.5
5. Sodium-adsorption-ratio = Na+// (Ca"1"1" + Mg"1"1")/^, where Na+, Ca++,
and Mg++ refer to the concentrations of designated cations expressed in
millequivalents per liter as found in calculations no. 2 through k.
6. Saturated water percentage = [(B-C)/(C-A)] X 100.
3.3 MINERALOGICAL METHODS
3.3.1 Summary
Minerals occurring in overburden materials can be identified using a
petrographic microscope or x-ray diffraction unit. Individual soil or
rock grains are identified by placing the grains in an oil with a known
index of refraction and examining them with the aid of a petrographic
microscope. Individual grains and their relationships to surrounding
grains are identified and examined in thin section using the petrographic
microscope. Using x-ray diffraction, the types of clay minerals present
in a sample can be determined.
All of the procedures require some technical knowledge for the mineral
identification. A person experienced in the use of a petrographic
microscope and/or x-ray diffraction instrument should make the identi-
fications.
99
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3.3.2 Identification of Grains by Immersion Method
3.3.2.1 Principle—
Many minerals may be identified by measuring their indices of refraction
and then referring to determinative tables. The index may be measured by
using the immersion method. Liquids of known index of refraction ranging
from about 1.U3 to 1.71 in steps of 0.01 should be available. The mineral
grains to be identified are placed on a glass slide, covered with liquid
of known index, and a small cover glass placed on top of the liquid. The
grains are then observed under a petrographic microscope using a medium
power objective. If the mineral grains have the same index as the liquid,
they will be practically invisible. If the grains do not "match" the
liquid, one can determine whether the grains have a higher or lower index
than the liquid by the Becke Line Test. When a mineral grain is slightly
out of focus, a narrow line of light known as the Becke line forms near
the edge of the grain. The line is usually more conspicuous if light is
reduced by partially closing the diaphragm in the substage. If the tube
of the microscope is raised (or microscope stage lowered), the Becke line
will move into the medium of higher index. In this way, it is possible to
determine whether the grain has an index higher or lower than the liquid.
As an example, if the grain is lower than the liquid, a new immersion is
prepared using a liquid of lower index of refraction. If the grain still
does not have the same index as the liquid, different liquids are used until
a match is attained. In using a white light source, two Becke lines form
when the grain and liquid are nearly matched—one line is yellowish and the
other line bluish. When the microscope tube is raised, the brighter of
these two lines moves toward the medium of higher index. The grain and
liquid have the same index of refraction when the intensities of these
two lines are the same.
3.3.2.2 Comments—
Amorphous material (no crystal structure) and isometric (cubic) crystals
are said to be optically isotropic, having only one index of refraction
which can be measured at any position of the microscope stage. All other
minerals have two or more indices of refraction and are said to be aniso-
tropic. Isotropic substances remain dark as the microscope stage is rotated
with crossed nicols (upper polarizing element inserted). Anisotropic
minerals, on the other hand, will generally be illuminated under crossed
nicols, becoming dark every 90 degree turn of the microscope stage. These
dark settings are called extinction positions. At these extinction positions
the indices of refraction of anistropic minerals are measured.
Hexagonal and tetragonal minerals have two indices of refraction called
n0 and nE. A mineral is said to be positive when n0 is less than nE and
. negative when n0 is larger than nE. The index n0 can be measured on any
| grain by turning the stage to the low index extinction position in a posi-
tive mineral or to the high index position for a negative mineral. At the
other extinction position an index called nE'lying between n0 and'the true
n is obtained.
100
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In positive minerals the highest value of nE", as determined on several
grains of the same mineral, is closest to true nj«. In a negative mineral,
the lowest value obtained vould be closest to n^. Precise measurements
of ng require use of interference figures which are explained in standard
optical mineralogy textbooks.
Orthorhombic, monoclinic, and triclinic minerals have three indices of
refraction with the lowest index called nx, the intermediate index ny, and
the highest index ng. Exact determination of these indices involves some-
what complicated techniques which are explained in standard optical
mineralogy textbooks. However, if several grains of the same mineral are
examined, the lowest index obtainable on any of these grains will be fairly
close to the nx index. The highest index obtainable on the grains will be
close to the ng index. The difference between the highest and lowest index
in a given mineral is called birefringence.
Most minerals under crossed nicols will show spectral colors called inter-
ference colors. Interference colors result from the double refraction of
light in the crystal. As the two rays emerge from the grain, they undergo
interference as they combine in passing through the upper nicol. The color
sequence is the same as in Newton Colors. The actual color observed depends
on the thickness of the grain, its orientation, and difference between its
highest and lowest index (birefringence). A mineral in randomly oriented
grains of the same thickness will show all of the colors up to a certain
maximum on the Newton Scale. This maximum color is very useful in identi-
fication. Although the general properties of two minerals may be quite
similar, their interference colors may be clearly different.
Most of the 50-100 mesh constituents in a soil can be readily identified
with the petrographic microscope by the immersion method using liquid
1.5^- The most common minerals and rock particles with their distin-
guishing features are as follows:
1. Quartz can be distinguished from most other minerals by the fact that
its low index (ng) is always 1.5^- The birefringence of quartz is weak
and is similar to that of feldspar. However, unlike feldspar, quartz has
no cleavage and is free of alteration or weathering to argillaceous or
clayey material.
2. Chert, which is an aggregate of fine-grained quartz, may occur as
grains in soil. Chert has the same optical properties as coarse quartz
but under crossed nicols shows a mosaic or salt and pepper effect because
of the diverse orientation of constituent quartz domains. Chert is
distinguished from aggregates of clay which sometimes have a mosaic
appearance by its lower index of refraction.
3. Orthoclase can be distinguished from most other minerals because its
indices of refraction are noticeably lower than 1.5^- The grain edges
are commonly straight and parallel because of cleavage. Orthoclase is
usually not as clear as quartz due to alteration. The birefringence of
orthoclase is weak.
101
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4. Microcline is similar to orthoclase but under crossed nicols shows
spindle-shaped twin plates. Plates meet at right angles forming a grid-
iron-like pattern.
5. Plagioclase commonly shows parallel bands or stripes under crossed
nicols because of twinning. The indices of refraction of plagioclase
vary with its composition. The more sodium-rich plagioclases have
indices below 1.5UU but not as low as potassium-rich feldspars.
Plagioclases with a small amount of calcium have indices close to 1.5^.
The calcium-rich plagioclases have indices well above 1.5^.
6. Muscovite occurs in colorless flakes with indices of refraction
considerably higher than that of quartz or feldspar. In immersions, these
flakes have a gray color under crossed nicols.
T. Biotite also occurs in flakes and in immersions under plain light
is dark brown or less commonly green. Under crossed nicols hardly any
light passes through the flakes.
8. Carbonate in the form of calcite or dolomite has a very high index
in one extinction position and a low index near or below 1.5^ in the other
extinction position. This change in index as the stage is rotated is
ordinarily very conspicuous and distinguishes carbonate from most other
minerals. Under crossed nicols, carbonates have a unique pinkish tan
color. Small carbonate particles mixed with clay may be recognized by
introducing the substage condensing lens and crossing the nicols. Under
these conditions, the carbonate will normally appear as bright specks.
9. Pyrite is opaque even with strong transmitted light obtained with the
substage condensing lens. In reflected light pyrite has a brass yellow
color and the crystal faces or polished surfaces look like metallic mirrors.
10. Limonite (goethite) is yellow or brown on thin edges under strong
transmitted light and opaque in thicker masses. Under reflected light,
limonite is yellowish brown to brown.
11. Hematite is opaque and black in reflected light where massive but
commonly translucent and red in reflected light at thin edges of the mater-
ial.
12. Sandstone fragments are recognized by the constituent grains of
quartz which have the characteristic low index of 1.5UU and gray to
white interference colors. The grains may be bound together by cement
of quartz, carbonate, clay or iron oxide.
13. Shale and mudstone usually show a fine layering due to parallel align-
ment of flakes of clay minerals. The index of refraction is moderately
high (distinctly higher than 1.5^*0 and interference colors are white to
yellowish white. The fragments go to extinction when the layering is
parallel to the polarizing elements because of the parallel alignment of
the constituent clay minerals.
102
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lU. Limestone fragments have a high index of refraction which causes the
fragments to appear somewhat dark. Under crossed nicols the fragments have
a slight pinkish tan color. If the constituent grains are sufficiently
coarse, a change from high to low index can be observed on a given grain
as the microscope stage is rotated.
15. Glass may develop in the partial fusion of shale (red dog). Glass is
amorphous (no crystal structure) and remains dark as the stage is turned
under crossed nicols. Glass also has a lower index than most minerals
(lower than 1.5^*0 and commonly contains small air bubbles.
3.3.2.3 Chemicals—
1. Acetone (CI^COCHj), reagent grade.
2. Dispersing agent: Dissolve 35.7 g sodium metaphosphate (Fisher
S-333 or equivalent) and 7 = 9** g sodium carbonate and dilute to 1 liter
with distilled water.
3. 1.5^ Index oil (available from R. P. Cargille Laboratories, Inc.,
Cedar Grove, N.J. 07009 or other suppliers).
3.3.2. It. Materials—
1. Polarized petographic microscope with micrometer stage with 10 X
eyepiece and a range in objectives from 3.5 to 50 X.
2. Variable intensity white light source.
3. 7.62 X 2.5*). cm (3 x 1 in) glass microscope slide.
h. Slide cover glasses.
5. Thermometer 0-100°C in 1°C divisions.
6. Sieve, 0.25 mm openings (60 mesh).
7. Sieve, 0.177 nun openings (80 mesh).
8. Shaker, horizontal reciprocating type, 6.3 cm (2.5 in) stroke, 120
strokes per minute.
9. Beakers, 250 ml, low-form.
10. Bottles, 950 ml (32 oz dry square).
11. Two beakers, UOO ml, low-form.
12. Two polyethylene bottles, 250 ml.
13. Lens paper.
103
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14. Balance, can be read to 0.1 §.
3.3.2.5 Proc edur e —
1. Mix bulk field sample thoroughly. CAUTION: Do not use steel utensils
to mix sample as some magnetic minerals may be attracted to the iron in the
steel.
2. Weigh approximately 100 g of fine-textured (50 g of coarse textured)
minesoil.
3. Place weighed sample in a 950 ml (32 oz) dry square bottle.
k. Add 20 ml of dispersing agent.
5. Place bottle on reciprocating shaker. Shake sample overnight.
6. Make a nested series with the 60 mesh and 80 mesh sieves placing the 60
mesh sieve on top.
7. Wet sieve entire sample, being sure to thoroughly wash sample from
the bottle.
8. Place sample retained on 80 mesh in a 250 ml beaker. Oven dry sample.
9. Thoroughly mix dried sample. NOTE: See caution step 1.
10. Fill two 250 ml polyethylene bottles with acetone. Label one bottle
"Acetone Wash" and the second bottle "Acetone Rinse." Similarly label two
ml beakers.
11. Pour acetone from bottle marked "Acetone Wash" into corresponding
ml beaker. Repeat for bottle marked "Acetone Rinse."
12. Thoroughly wash and then rinse glass microscope slide and glass slide
cover.
13. Air dry glass microscope slide and glass slide cover.
Ik. Return acetone to appropriate polyethylene bottles. NOTE: The acetone
can be used for several wash and rinse cycles. Throw out acetone in
"Acetone Wash" bottle when it becomes too contaminated to thoroughly wash
slides. Replace discarded acetone from "Acetone Wash" bottle with acetone in
"Acetone Rinse" bottle. Put fresh acetone in "Acetone Rinse" bottle.
15. Thoroughly clean glass microscope slide and cover glass with lens
paper.
l6. Thoroughly clean microscope lens and mirror with lens paper.
17. Place a few grains of the thoroughly mixed oven-dry sample on a glass
microscope slide.
104
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18. Add 1.5UU index oil by drops until all grains are covered.
19. Place one edge of the cover glass on the microscope slide. Gently
lower the opposite edge being careful not to trap air bubbles under the
cover glass.
20. Place slide on microscope stage.
21. Adjust white light source, microscope mirror, and microscope diaphragm
for best light refraction without being strongly bright.
22. Move stage micrometer to one corner of the cover glass. Note both
micrometer readings.
23. While moving stage micrometer in increments of one and doing one row
at a time, count various types of grains (see 3.3.2.2) as they appear
under the cross hairs until the area under cover glass has been completely
covered.
2k. Record results for each slide.
25. Thoroughly wash and rinse slide and cover glass (see steps 11-lit).
Discard grains from bottom of beaker after washing.
3.3.3 Petrographic Analysis of Thin Sections
3.3.3.1 Principle—
Overburdens and minesoils can be studied in slices called thin sections
which are 30 microns thick. Thin sections are examined under the
petrographic microscope and are useful in observing how individual
constituents are arranged and in determining the size and shape of pores.
The technique of studying morphological features under the microscope is
basically an extension of methods used in studying samples with a hand
lens or the unaided eye.
3.3.3.2 Comments—-
Coherent samples can be thin sectioned directly but friable samples have to
be impregnated usually with a polyester resin (Buol and Padness, 1961).
Normally thin sections are prepared by professionals who advertise in several
geological and mineralogical journals and magazines.
Thin sections should first be examined with low magnification to study
larger scale features and familiarize the observer with the minerals and
fabrics within the thin section. Magnification is increased to observe
finer details. Observation with transmitted light is conducted in plain
light, crossed polarized light with and without substage condensing lens,
and with light stopped down to different degrees. Some features may be
more visible in reflected light. The determination of approximate percentage
105
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of constituents can be ascertained by visual estimation. More accurate
determinations can be made by counting the different kinds of grains, voids
and special features.
The mineral composition of the larger grains (skeletal grains) observed
in thin section can be determined by procedures similar to those used in
the immersion method (see 3.3.2.2). The larger grains are generally
embedded in a matrix of very fine-grained material composed largely of
fine silt and clay. Some of the matrix material may be identified
(see 3.3.2.2) but complete identifications require x-ray diffraction and
differential thermal analysis.
More information on identification of minerals in thin sections may be
obtained from Cady (1965) and Kerr (1959); however, the following special
features may be seen in thin sections:
1. Cuban is a general term coined by Brewer (196k) to designate accumu-
lations on soil particle surfaces or textural changes along a surface of
movement. Accumulations may be composed of various materials such as clay,
organic matter, silica, iron oxides or hydroxides, or manganese oxides
or hydroxides.
2. Argillans or clay skins are cutans composed of clay minerals and occur
on the natural surfaces of soil particles. They have a smooth or ropy
surface with a waxy luster in reflected light. In thin sections they have
the same index as the clay matrix but a higher index than that of quartz
or feldspar grains. Under crossed nicols argillans commonly appear as
white borders on grains or soil units. The borders go to extinction at
the points where they are parallel to the polarizing elements ("north-south
and east-west").
3. Ferrans are iron oxides or hydroxides occurring on soil surfaces.
In thin sections they are translucent or opaque. Under reflected light
they are yellow, brown, or red.
It. Mangans are manganese oxides or hydroxides which are usually opaque
and very dark brown or black in reflected light.
5. Concretions differ in composition from the material which surrounds
them. Concretions may be composed of any mineral matter, but they are
more commonly made up of carbonate, chert, sulfate, or oxides and hydroxides
of iron or manganese. Normal technqiues of mineral identification are
used to distinguish between the different types of concretions.
6. Earthworm casts appear as tubes of material commonly containing rounded
aggregates representing excreta. The aggregates have dark outer borders
of humus and may occur in clusters.
7. Root channels are voids left from decayed roots. These voids resemble
worm burrows but may contain remnants of roots with characteristic cellular
structure. The channel system may also show more of a tree-like pattern
than do the worm burrows.
106
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8. Pores (voids) in thin sections are colorless in plain light and remain
black when the stage is rotated under crossed nicols. The percentage of
observed pores can be estimated by visual inspection or determined more
accurately by the point count method as described by Anderson and Binnie
(1961).
The shape of the pore may be spherical, tubular, planar, or irregular.
Spherical voids are commonly referred to as vesicles, some of which result
from gas bubbles or solution of spherical grains. The apparent shape of
the other pores depends on how they are cut during thin section preparation.
Tubular pores will appear round in sections cut at right angles to the
tubes. The shape will be elliptical and more elongate the more nearly the
section parallels the length of the tubes. Tubular pores commonly result
from burrowing by earthworms and insects or from the decay of plant roots.
The cut of the section is not as critical in recognizing planar voids,
although the true width of the opening can be determined only on sections
at right angles to the plane of the voids. The planar voids commonly
originate as a result of shrinkage of soil material as it dries.
Our data show that soil fabrics, as described by Brewer (196*1-), do not
normally occur in young minesoils. Remnant soil fabrics may be seen in
minesoils that have been "top soiled" or mixed with a natural soil.
More details on soil fabrics can be found in Brewer (196*0. Sampling
procedures and number of grains to be counted are given by Cady (1965),
Kerr (1959K and Winchell (1937)- Accurate percentage determinations by
point counting methods are given by Hutchison (197*1-) and Anderson and
Binnie (1961).
3.3.3. 3 Chemicals—
Hone required.
3.3.3.4 Materials—
1. Polarized petrographic microscope with micrometer stage with 10 X
eyepiece and a range of objectives from 3.5 to 50 X.
2. Variable intensity white light source.
3.3.3.5 Procedure—
1. Place thin section on the stage of the petrographic microscope.
2. Adjust light intensity so grains can be easily seen.
3. Examine thin section under low magnification. Use higher magnification
to clarify details.
k. Determine kinds of voids and percent por'osity.
5. Examine for oriented clay bodies and determine position and percentage
in sample.
107
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6. Determine mineralogy and percentage of the skeletal grains.
7. Examine for special features (see 3.3.2.2) and record percentage of
each.
3.3.U Identification of Clay Minerals by X-Ray Diffraction
3. 3. U.I Principle—
The clay minerals of greatest interest (e.g. kaolinite, illite (mica),
vermiculite, chlorite, and montmorillonite) are mostly flaky or platy in
shape. They are readily identified and distinguished from one another by
observing the effect of different chemical and heat treatments on the inter-
layer spacings along the axis perpendicular to the platy surfaces with the
use of x-ray diffraction.
The pretreatment used to distinguish montmorillonite from vermiculite
and chlorite and to identify illites is saturation of the exchange complex
of the clay with magnesium and treatment with glycerol. Vermiculite is
distinguished from chlorite and kaolinite by saturating the clays with
potassium and heating on a. glass slide at 500°C. Intermediate heat
treatments, 110°C and 250°C, can be used to study inter layering in the
collapsing minerals or other special problems. Stronger x-ray diffraction
peak intensities are obtained due to preferred orientation of the clays on
the glass slide. This preferred orientation results since the clay plates
settle parallel or nearly parallel upon drying from the suspension.
3.3.^.2 Comments —
Due to the length of time involved in sample preparation, several samples
should be prepared at the same time. The commonly used radiation sources
are copper and cobalt. If copper radiation is used, free iron oxides will
have to be removed (see Jackson, 1958 p. 168) to eliminate interference.
Interpretation of data should be performed by a person qualified in x-ray
analysis and clay mineralogy.
3. 3. U. 3 Chemicals —
1. Sodium hydroxide (NaOH), 1 N_: Dissolve UO.O g of NaOH pellets with
carbon dioxide-free water (See 3.2.3.3 No. l) and dilute to a volume of
1 liter. Protect from C02 in air with ascarite tube.
2. Sodium carbonate (NagO^), 1 N_: Dissolve 53 g of Na2C03 with
carbon dioxide-free water (See 3.2.3.3 No. l) and dilute to a volume of
1 liter. Protect from COg in air with ascarite in a guard tube.
3. pH 10 water: Dilute 10 ml of 1.0 N_ Na2C03 to 10 liters with
distilled and deionized water. Check pH with a pH meter and adjust to
pH 10 by the addition of 0.1 W_ HC1 or 1.0 N Na2C03.
k. Acetone
108
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5. Hydrochloric acid (HCl), 1.0 H_: Dilute 83 ml of concentrated HC1 to
a volume of 1 liter with distilled water.
\
6. Hydrocholoric acid (HCl), 0.1 N_: Dilute 100 ml of 1 If HCl to a volume
of 1 liter with distilled water.
7. Bromophenol Blue.
8. Hydrogen peroxide (H202), 30% » ACS certified (without added preservative).
9. Sodium acetate (NaC2H302), 1 N: Dissolve 82 g of NaC2H302 with dis-
tilled water and dilute to a volume of 1 liter. Buffer to pH 5.0 with
acetic acid or sodium hydroxide.
10. Magnesium chloride (MgCl2-6H20) , 1 N_: Dissolve 102 g of MgCl2-6H20
with distilled water and dilute to a volume of 1 liter.
11. Magnesium chloride (MgCl^HgO) , 10 N: Dissolve 1020 g of MgCl2-6H20
with distilled water and dilute to a volume of 1 liter.
12. Potassium chloride (KCl), 1 N: Dissolve 7^.5 g of KC1 with distilled
water and dilute to a volume of 1 liter.
13. Potassium chloride (KCl), 10 N.: Dissolve 7^5 g of KCl with distilled
water and dilute to a volume of 1 liter.
. Magnesium acetate (Mg(C2H302)-UH20) , 1 K_: Dissolve 107 g of Mg(C2H302)-
with distilled water and dilute to a volume of 1 liter.
15. Potassium acetate (CH3COOK), 1 N: Dissolve 98 g of CH3COOK with
distilled water and dilute to a volume of 1 liter.
16. Methanol (CH3OH).
17. Silver nitrate AgN03, 10$ : Dissolve 10 g of AgN03 with distilled
water and dilute to a volume of 100 ml.
18. Glycerol solution, 20$ : Dilute and mix 20 ml of glycerine
(CH2OHCHOHCH2OH) to 100 ml with distilled water.
3.3.**.** Materials—
1. Balance, can be read to 0.1 g.
2. Soil dispersion mixer with baffled cup.
3. Sieve, 300 mesh.
k. Rubber policeman.
5. Funnel, large powder, polyethylene.
109
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6. Beakers, 1000 ml, 600 ml, and UOO ml.
7. Drying oven.
8. Spatula.
9. Spot plate.
10. Hot plate.
11. Centrifuge bottles, 250 ml with screw caps and centrifuge tubes, 50 ml.
12. Centrifuge; equipped with tachometer and timer (IEC Model K with No. 277
and 279 heads or equivalent centrifuge with U-place and 12-place heads).
13. Bottle, French square, 1 liter (32 oz) capacity.
1^. Shaker, horizontal reciprocating type, 6.3 cm (2.5 in) stroke, 120
strokes per minute.
15. Flask, Florence, 2000 ml with rubber stopper.
16. Vacuum desiccator.
17. X-ray diffraction instrument.
18. Glass x-ray slides.
19. Vortex mixer.
3.3.^.5 Procedure—
NOTE: If soil samples are analyzed instead of rock samples, omit 3.3.^-5.1-
3.3.*<-.5.1 Separation of clay from rock samples — The following steps are
for the separation of clay from rock samples only.
1. Weigh 100 g of ground (less than 60 mesh) rock material in a 600 ml
beaker.
2. Add 300 ml distilled water.
3. Adjust the pH to 8.5 with 1.0 N NaOH.
k. Transfer suspension to metal container used with the soil dispersion
mixer.
5. Fill to two-thirds of the container's volume with pH 10 water.
6. Stir suspension vigorously (using soil dispersion mixer) for 30 to 60
minutes.
110
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7. Pour most of the suspension (all except heavy soup near bottom of
container) into a 300 mesh sieve, aiding passage of the suspension through
the sieve with a gentle jet of pH 10 vater. NOTE: Sieve should be mounted
in a large polyethylene funnel leading into a 1000 ml beaker.
8. Wash residue remaining on sieve with a gentle jet of pH 10 water, gently
breaking up any clay or silt lumps with a rubber policeman.
9. Add pH 10 water to residue in the metal container and repeat steps 5
through 8.
10. Repeat step 9 until most of the silt and clay has been washed from the
container. Transfer the sand in the container to the sieve and wash several
times with a jet of pH 10 water, being certain to break up the lumps of silt
and clay with a rubber policeman.
11. Wash sand with acetone to remove most of the water.
12. Dry the sand. After drying, shake sieve for about 10 minutes either by
hand or mechanical shaker. Add material that passes sieve to the 1000 ml
beaker containing silt and clay fractions.
13. Carefully pour contents of the sieve onto a black glazed paper,
turning the sieve over and tapping its rim with the handle of a spatula.
1^. Weigh sand and store in vial if analysis of the sand is desired. If
sand is not needed for analysis, discard after weighing.
15. Go to 3.3.^.5.2 step 18.
3.3.U.5.2 Separation of soil fractions — The following steps are for
separation of soil fractions only.
1. Weigh 50 g of soil and transfer to a 1000 ml beaker.
2. Add 150 ml deionized water.
3. Adjust to pH 3.5 with 1.0 IJ HC1 using bromophenol blue indicator and a
spot plate. So as not to lose any soil, wash the drops of suspension on
the spot plate back into the original beaker.
h. Add 25 ml of 30$ 1^02 and cover with a watch glass. Allow to stand
overnight without heating.
5. The following day, add an additional 25 ml of 30$ H202 and heat gently
to 90°C on a hot plate. Continue heating for at least one hour maintaining
the sample at 90°C. NOTE: If the soil contains a large amount of organic
matter, add an additional 25 ml of HL^Q after 1 to 2 hours and continue to
repeat the additions until most of the organic "scum" is destroyed (this may
take all day with 3 or h applications of
Ill
-------
6. Wash soil into a 250 ml centrifuge bottle, adjust to pH 3.5 if necessary,
and centrifuge at 1,500 RPM until the supernatant liquid is clear (about 5
minutes). '
7. Discard the clear liquid, transfer soil to a UOO ml beaker and adjust to
pH 10 using a pH meter and 1.0 H_Na2C03 solution.
8. Pour suspension into a 1 liter bottle and fill to two-thirds of volume
with pH 10 water.
9. Place horizontally on a reciprocating shaker and shake for 16 hours at
120 strokes per minute.
10. Place a 300 mesh sieve in a large polyethylene funnel and place funnel
over a 1000 ml beaker.
11. Pour most of the suspension from the bottle into the sieve, washing
silt and clay through sieve with a gentle jet of pH 10 water.
12. Wash remaining material from the bottle onto the sieve with a gentle jet
of pH 10 water.
13. Wash silt and clay through sieve with a jet of pH 10 water, breaking
silt and clay lumps with a rubber policeman.
l4. Wash remaining sand with acetone to remove most of the water.
15. Dry sand. Add a sieve cover and receiving pan to the sieve and
vigorously shake either by hand or mechanical shaker for 10 minutes.
Material passing sieve is added to the 1000 ml beaker containing silt and
clay fractions.
16. Carefully pour the contents of the sieve onto black glazed paper,
turning the sieve over and tapping its rim with the handle of a spatula.
17. Weigh sand and transfer to storage vial. If sand is not needed for
analysis, discard after weighing.
18. Pour contents of the 1000 ml beaker into a 250 ml centrigute bottle,
using one bottle per sample. Balance bottles. Centrifuge at 2000 RPM for
5 minutes. Pour supernatant suspension into a 2000 ml Florence flask
labeled less than 2 micron fraction. NOTE: Since all of the suspension in
the 1000 ml beakers will not fit into the 250 ml centrifuge bottle, centri-
fuging must be repeated by making additions to the bottle after each
decantation until all of the suspension in the 1000 ml beaker is centrifuged.
Do not stir material in the bottom of the-centrifuge bottle between these
additions.
19. After all of the suspension in the 1000 ml beaker has been added and
centrifuged, add pH 10 water to the bottles, stir, and centrifuge at 1500
RPM for 10 minutes. Decant supernatant liquid into the Florence flask.
112
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20. Add pH 10 water, stir, and this time centrifuge at 1600 RPM for exactly
2 minutes. Decant into the Florence flask.
21. Repeat step 20 until the supernatant liquid is about clear. NOTE: If
the Florence flask becomes filled, an auxiliary container such as a 2000 ml
beaker can be used. Both the Florence flask and the auxiliary container
must be kept covered with a stopper or watch glass.
22. Add 20 ml of 1 W_ NaC2H302 to flocculate the clay. After clay flocculates,
siphon off as much of the liquid as possible without removing any of the clay.
23. Stir remaining liquid and clay by hand and pour mixture into a beaker.
2k. Wash remaining clay from the Florence flask into the beaker with
deionized water.
25. Place beaker in a vacuum desiccator, attach vacuum line, and evaculate
until clay is air-dry.
3.3.1*. 5.3 Mg (or K) saturation of clay fraction — The following steps
include procedures for either Mg or K saturation of clays depending on
analyses required.
1. Weigh 0.10 g of air-dry clay and suspend in 100 ml of 1 N NaC2H302
(buffered to pH 5.0) in a 250 ml centrifuge bottle. Boil gently for 5
minutes.
2. Add 20 ml of 1 N_ MgCl2'6H20 (or KC1 for samples to be K saturated) to
the suspension.
3. Mix the suspension thoroughly and centrifuge at 2000 RPM for 5 minutes.
It. If the supernatant liquid is clear, discard the liquid; if not, add
10 ml of 10 K_MgCl2-6H20 (or KCl) to insure flocculation. Centrifuge and
discard clear supernatant liquid.
5- Wash clay once with 1 M_ Mg(C2H302)-lffi20 (or CHoCOOK) and twice with 1
N_ MgCl2'6H20 (or KCl) to remove acetates centrifuging and discarding clear
supernatant liquid between washings.
6. Wash and centrifuge clay twice with 20 ml deionized water and then with
methanol until free from chlorides (Cl~ is present if a precipitate occurs
with the addition of a few drops of 10$ AgW03 to a few ml. of the supernatant.
T. Pipet about half the suspension. Spread suspension on a glass slide
and allow to dry at room temperature (25°C)(see 3.3.^.5.5, step 2).
8. Dry remaining clay over drierite in a desiccator at room temperature
(25°C) and proceed directly to glycerol solvation (3.3.H.5.1+) if glycerol
treatment is needed; if not, proceed to 3.3.^-5.5.
113
-------
3.3.^.5.^ Glycerol solvation — The following steps are necessary if
glycerol saturation is required.
1. Weigh 0.050 g air-dry clay (Mg saturated) and place in a 50 ml centri-
fuge tube.
2. Add 0.5 ml of 20% glycerol solution.
3. Let stand for 30 minutes, centrifuge, and let drain for at least 30
minutes.
h. Add about 1 ml of water to the centrifuge tube to make a free flowing
slurry and mix using a Vortex mixer.
3.3.^.5.5 Slide preparation and treatment selection — From the following
steps, x-ray slides can be prepared and proper treatments chosen.
1. Select appropriate treatments and temperatures from Tables 9 and 10.
NOTE: All heat treatments are heated at the given temperatures for 2 hours.
2. Carefully pipet 1 or 2 ml suspension onto glass slide. Do not allow
suspension to run off the glass slide, but cover an area large enough to
cover the entire x-ray beam.
3. Dry at room temperature (25°C).
k. Run x-ray analysis following manual supplied with the x-ray diffraction
equipment.
5. Perform appropriate treatments as determined in 3.3.^.5*5, step 1.
Rerun slides on x-ray diffraction unit.
o
6. Determine basal spacing in angstroms (A) depending on type of radiation
used.
7. Determine type of clay minerals using data from Tables 9 and 10.
3.3.^.5.6 Explanatory notes — The following notes are for Tables 9 and 10.
1. Peaks sharp and higher orders distinct; beidellite closes easier on
K saturation than montmorillonite from bentonite.
2. Peaks broad; higher orders very weak.
3. Peaks broader than mica; higher orders not quite as distinct and may 0
not be exactly integral; may be interstratified with montmorillonite; 10 A
peak sharpened on heating clay.
k. First order peak sharper than montmorillonite but not as sharp as mica;
higher orders are weak.
o
5. Strong 2nd order reflection; peaks sharp; spacing may vary +_ 0.2 A.
Ilk
-------
TABLE 9. BASAL SPACINGS OF CLAY MINERALS AS INFLUENCED BY
Mg-SATURATION AND GLYCEROL TREATMENTS
Basal Spacings
(A units)
Mineral Name
Mica
Montmorillonite (mont.)
Illite
Vermiculite (verm. )
Chlorite
Interstratified mont.
and illite
Interstratified verm.
and chlorite
Interstratified verm.
and illite
Montmorillonite with
"inter layer islands"
Vermiculite with
"interlayer islands"
Interstratified mont. with
"islands" and illite
Interstratified verm, with
"islands" and illite
Kaolinite
Hydrated halloysite
Dehydrated halloysite
H20
25°C
10
12-15
10
14.5
14.4
11-14
14.5
11-14
14-15
14-15
11-14
l^U
7.0-7.2
10
7.2
glyc
25°C
10
18
10-11
14.7
14.4
15-17
14.6
11-14
14-15
14-15
n-14
JWi
7.0-7.2
10
7.2
Notes
(see 3.3.4.5.6)
1
2,
3,
^
5,
6,
6,
6,
7,
7,
7,
7,
8,
8,
9
10
10
10
10
10
10
10
10
10
10
10
10
9
115
-------
TABLE 10. BASAL SPACINGS OF CLAY MINERALS AS INFLUENCED
BY K-SATURATION AND HEAT TREATMENTS
Basal Spacing
Mineral Name
Mica
Montmorillonite (mont. )
Illite
Vermiculite (verm. )
Chlorite
Interstratified mont.
and illite
Interstratified verm.
and chlorite
Interstratified verm.
and illite
Montmorillonite with
"interlayer islands"
Vermiculite with
"interlayer islands"
Interstratified mont.
with "islands" and illite
Interstratified verm.
with "islands" and illite
Kaolinite
Hydrated halloysite
Dehydrated halloysite
25°C
10
10-12
10
10.5
14.4
10-11
11-13
10-11
Ik
11-14
11-14
n-i4
7-0-7.2
10
7.2
100°C
10
10
10
10.2
14.4
10
11-13
10-11
13-14
11-14
11-14
11-13
7.0-7.2
7.2
7.2
__
(A units
300°C
10
10
10
10.1
Ik.k
10
11-13
10-11
11-12
11-12
11-13
11-13
7-0-7.2
7.2
7.2
)
Notes
525°C (see 3.3.4.5-6)
10
10
10
10.1
Ik.k
10
11-13
10
10-11
10-11
10
10
None
None
None
1
2,
3,
k,
5,
6,
6,
6,
7,
7,
7,
7,
8,
8,
9
10
10
10
10
10
10
10
10
10
10
10
10
9
116
-------
6. Higher orders not integral.
7. Peaks may not sharpen on heating but shift to smaller "d" values.
8. Well crystallized kaolinite has a sharp peak at 7.0 A and higher
orders are present; poorly crystallized kaolinite has a broader peak
at 7-2 and may be confused with halloysite.
9. If hydrated halloysite is oncg dried in the absence of some excess
salts it does not reexpand to 10 A. If dried in a slurry of HC1 or
o
the spacing remains at 10 A.
10. All 2:1 minerals are probably interstratified or interlayered with
"islands" of nonexchangeable groups to some degree. When it is slight there
is some shifting of the spacing indicated. The greater the proportion of
a particular phase, the more the spacing will be like that of the pure
mineral.
PHYSICAL METHODS
Summary —
The methods listed in this section are primarily for minesoil and soil
materials. These methods measure parameters that dictate the long-term
use of the soil. Where chemical properties are of extreme importance in
the short term, physical properties of minesoils are extremely important
to long-term management and use. Chemical properties can be more easily
modified and changed than physical properties.
The size distribution of particles can be measured by either of the two
methods, pipette or hydrometer. The pipette (3.^.2) is the more exact
while the hydrometer method (3.^.3) is less time consuming. Bulk density
can be measured by methods 3.h.k through 3.^-7. The type of materials found
in minesoils with the large variety of particle sizes dictated that more than
one method be presented to the user for measuring bulk density. The other
methods are self-explanatory and need no further clarification; however,
material used in each of the physical methods is only sieved when taken
from the field and not subjected to grinding.
3.^.2 Particle Size Analysis (Pipette Method)
3.^.2.1 Principle —
The pipette method depends on differential settling rates of silt- and
clay-size soil particles from a water suspension. Since large particles
settle faster than small particles of similiar density (as stated by Stokes1
Law) , sampling a suspension at constant depth over increasing longer periods
of time will yield increasingly smaller sizes of the suspended solids. By
sampling the suspension with a pipette at a 10 cm depth at the time cal-
culated from Stokes' Law, a sample of specific equivalent particle sizes
will have already settled past the 10 cm depth at each sampling time.
117
-------
3.U.2.2 Comments —
Normally soil samples are pretreated with hydrogen peroxide to remove
organic matter. Materials which contain concentrations of soluble salts
and gypsum must be leached with enough water to remove them before good
dispersion of the sample can be accomplished. If the need should arise,
procedures for the removal of organic matter, soluble salts, and gypsum are
available (Day, 1956; Kiljner and Alexander,
3.^.2.3 Chemicals —
Dispersing agent: Dissolve 3^.7 g sodium metaphosphate (NaCPOg)^) (Fisher
Scientific Co. No. S-333 or equivalent) and 7^9^ g sodium carbonate
in distilled water and dilute to one liter. The Na2COo is used as an
alkaline buffer to prevent the hydrolysis of the metaphosphate back to the
orthophosphate which occurs in acidic solutions. NOTE: Instant Calgon
available from Calgon Corp., Pittsburgh, Pa. can be used.
3.b.2.b Materials—
1. Sieve, 2 mm (10 mesh) openings.
2. Sieve, approximately .05 mm (300 mesh) openings.
•
3. Bottles, pyrex nursing, 237 ml (8 oz) with rubber stoppers.
4. Pipette, Lowry automatic, 25 ml (available from Arthur H. Thomas, Co.,
Philadelphia, Pa.).
5. Shaw pipette rack. NOTE: If not available, a substitute pipette rack
can be made using a cathetometer or a support stand with a sliding clamp.
The pipette rack is required for lowering and positioning the tip of the
pipette at a controlled depth below the upper mark of the 1000 ml graduated
cylinder.
6. Balance, can be read to 0.001 g.
7. Drying oven.
8. Hot plate
9. Wooden rolling pin.
10. Beakers, 250 ml.
11. Watch glass.
12. Desiccator with drierite desiccant.
13. Funnel.
lit. Rubber policeman.
118
-------
15. Shaker, horizontal reciprocating type, 6.3 cm (2.5 in) stroke, 120
strokes per minute.
16. Cylinders with a 1000 ml graduation (KIMAX brand (20023) or equivalent).
17. Aluminum pan.
18. Plunger (see 3.U.3.1* No. 6).
19. Vacuum assembly, vacuum source and suction hose with valves and trap to
control rate (Kilmer and Mullins 195^, Figure 6, p.
20. Weighing bottles, 60 ml capacity or 100 ml beakers.
3.^.2.5 Procedure (Adapted from Kilmer and Alexander, 19^9)—
1. Mix and quarter air-dry soil.
2. Roll one quarter with a wooden rolling pin to break up clods.
3. Pass sample through 2 mm sieve. NOTE: Rolling and sieving are
repeated until only rock fragments and pebbles are retained on the sieve.
CAUTION: Care must be taken to avoid breaking the rock fragments.
k. Material not passing the 2 mm sieve are weighed and reported as a
percentage of the air-dry weight of the whole sample.
5. Two 10.000 g samples of air-dry material passing the 2 mm sieve are
weighed.
6. One sample is placed in a weighing bottle and dried at 105°C overnight.
Then it is cooled in a dessicator and weighed to the nearest milligram.
This weight is recorded as organic-free, oven-dry weight.
7. The other 10.000 g subsample is placed in a 237 ml (8 oz) nurse bottle
with 10 ml of the dispersing agent.
8. Add distilled water to bring volume to about 177 nil (6 oz.). Stopper
bottle and shake overnight in a horizontal position on a reciprocating
shaker at 120 strokes per minute.
9.- After shaking, bring bottle to room temperature by allowing it to
stand for a few minutes if necessary.
10. Place 300 mesh sieve in a funnel and then place funnel in a 1000 ml
graduated cylinder.
11. Wash the dispersed sample on the 300 mesh sieve. Wash all sample from
the bottle using a jet of distilled water. CAUTION: Jets of water should
be avoided in washing the sample through the sieve. The funnel should be
gently tapped with the side of the hand to facilitate the washing procedure.
Care should be taken not to spill any material over the top of the sieve.
119
-------
12. Continue washing until the volume in the cylinder totals about 500 ml.
NOTE: Sands remain on the sieve. It is necessary that all particles of
less than about 50 microns diameter be washed through the sieve.
13. Remove sieve, place in a tarred aluminum pan and dry in the oven.
Cool sieve and transfer sands to the pan using a brush. Dry the pan and
contents for about 2 hours at 105°C. The pan is then placed in a desiccator
to cool and the contents weighed to the nearest 0.01 g.
Ik. Wash materials retained in the funnel into the cylinder. Bring volume
to 1000 ml graduation mark with distilled water.
15. Cover cylinder with a watch glass and set in sedimentation cabinet.
16. Place the Lowry pipette on the pipette rack.
17. Make adjustments required to immerse the pipette 10 cm in the suspension
when proper sampling time has arrived.
18. Attach vacuum line to pipette and adjust vacuum assembly to fill pipette
in 12 sec using distilled water.
19. Stir the material in the sedimentation cylinder for 6 minutes (8 minutes
if the suspension has stood for more than 16 hours) with a motor driven
stirrer. CAUTION: Do not let any of the suspension spill over the top of
the cylinder.
20. After mechanical stirring, stir the sample using an up and down motion
for 2 minutes with the plunger (see 3.^.3.^- No. 6). Record time at
completion of stirring and suspension temperature. NOTE: The temperature
should remain constant during the settling process by using a constant
temperature room or placing cylinders in a constant temperature bath.
Samples should be placed where they are free of vibrations.
21. Using Table 11, determine the settling time for the less than 20 micron
fraction.
22. About one minute before the determined settling time, the tip of the
pipette is lowered slowly into the suspension to a depth of 10 cm by means
of the pipette rack.
23. At the appropriate time, fill the pipette by controlled suction calibrated
to require 12 seconds to fill. Remove pipette. Drain freely into a pre-
weighed weighing bottle or beaker.
2k. Add' one rinse from the pipette to the weighing bottle or beaker using
distilled water.
25. Repeat steps 22 through 2k until all cylinders have been sampled for
the less than 20 micron fraction.
26. Restir samples for 2 minutes using an up and down motion with the plunger.
120
-------
TABLE 11. TIMES FOR PARTICLE SIZE ANALYSIS (PIPETTE METHOD)
BASED ON TEMPERATURE
°c
20°
21°
22°
23°
24°
25°
26°
27°
28°
29°
30°
Less Than 20 Micron
4
4
4
4
4
4
4
3
3
3
3
min.
min.
min.
min.
min.
min.
min.
min.
min.
min.
min.
40 sec.
33 sec.
27 sec.
20 sec.
Ik sec..
9 sec.
3 sec.
58 sec.
53 sec.
48 sec.
43 sec.
Less Than 2 Micron
466
455
444
434
424
415
405
396
388
379
372
min.
min.
min.
min.
min.
min.
min.
min.
min.
min.
min.
— *7
= 7
= 7
= 7
= 7
= 6
= 6
= 6
= 6
= 6
= 6
hr.
hr.
hr.
hr.
hr.
hr.
hr.
hr.
hr.
hr.
hr.
46
35
24
14
4
55
45
36
28
19
12
min.
min.
min.
min.
min.
min.
min.
min.
min.
min.
min.
27. Record time and temperature.
28. Using Table 11, determine the settling time for the less than 2 micron
fraction.
29^ Repeat steps 22 through 2k until all cylinders are sampled.
30. Dry weighing bottles or beakers in an oven at 90°C until the volume has
been reduced by one-half. Then dry for 12 hours at 105°C.
31. Cool in desiccator and record weights of the individual fractions.
32. Prepare a blank by placing 10 ml of the dispersing agent in a 1000 ml
graduated cylinder. Bring volume to 1000 ml with distilled water. Pipette
25 ml and place in preweighed weighing bottle or beaker along with one
rinse of the pipette. Dry at 105°C, cool in desiccator, and record weight
as weight correction factor for dispersing agent.
121
-------
3.^.2.6 Calculations—
1. % sand = (Weight of sand fraction/Weight of oven-dry, organic-free total
sample) X 100.
2. Constant (K) = 1000/Volume of pipette.
3. D = 100/Weight oven-dry, organic-free total sample.
IK % Clay = (A - B) KD, where:
A = Weight in grams of the less than 2 micron fraction plus dispersing
agent.
B = Weight in grams of dispersing agent correction.
5. % (20 to 2 micron) = [(A - B)KD] - (% clay), where:
A = Weight in grams of the less than 20 micron fraction plus dispersing
agent.
B = Weight in grams of dispersing agent correction.
6. % (50 to 20 micron) = 100 - [% sand + % clay + % (20 to 2 micron)].
7. % silt = (% 20 to 2 micron) + (% 50 to 20 micron).
3.U.3 Particle Size Analysis (Hydrometer Method)
3.^.3.1 Principle—
This method depends on the rate at which soil particles settle from a
water suspension. The soil particles are put into suspension by mechanical
stirring with the aid of a dispersing agent. Sodium metaphosphate solution
is used to disperse the soil and avoid flocculation of the clays. Sodium
replaces exchangeable calcium and the precipitation of the calcium, in the
form of calcium phosphate, prevents its recombination with the clays. The
net negative charge on the clay particles increases due to the addition of
sodium ions, causing the particles to repel each other and disperse. Since
large partilces settle faster than the same kind of small particles as
stated by Stokes1 Law, the concentration of soil particles in suspension
at a given time is dependent upon the size of the particles.
3.^.3.2 Comments—
Temperature is important in the sedimentation procedure since the density
and viscosity of water change with temperature. As the temperature
increases, the time required for particles to settle out of suspension
decreases. The hydrometer is usually calibrated for 19.k or 20°C (67 or
68°F). For each °F above the hydrometer calibration temperature, add 0.2 g
to the reading. Subtract 0.2 g from the hydrometer reading for each °F
below the calibration temperature. Although the correction factor for
122
-------
temperature can be used, it is best to carry out the procedure in a
constant temperature room or maintain the sedimentation cylinders in a
constant temperature bath.
The material is mixed using a reciprocating shaker; however, a soil
dispersion mixer with baffled cup (similar to a drink mixer) can be used
as an alternate method if a reciprocating shaker is not available. With
this apparatus, a weighed sample is placed in the baffled cup with distilled
water and dispersing agent. The cup is placed on the mixer and stirred for
a maximum of 5 minutes. Many minesoil samples can usually be mixed in
3 minutes.
3.U.3.3 Chemicals—
1. Dispersing agent: Dissolve 35.7 g sodium metaphosphate C
(Fisher Scientific Co. No. S-333 or equivalent) and 7.91* g sodium
carbonate (NagCC^) in distilled water and dilute to a volume of 1 liter.
The Na2CC>3 is used as an alkaline buffer to prevent the hydrolysis of
the metaphosphate back to orthophosphate which occurs in acidic solutions.
NOTE: Instant Calgon available from Calgon Corp., Pittsburgh, Pa. can
be substituted.
2. Distilled water.
3.U.3.U Materials—
1. Bottles, French square, 1 liter (32 oz) with caps.
2. Shaker, horizontal reciprocating type, 6.3 cm (2.5 in) stroke, 120
strokes per minute.
3. Glass sedimentation cylinder with markings at the 1130 ml and 1205 ml
levels (Bouyoucos cylinder).
k. Standard hydrometer (ASTM 152 H, with Bouyoucos scale in grams per
liter).
5. Balance, can be read to 0.1 g.
6. Plunger. NOTE: This can be made using 3 mm (0.125 in) diameter wire.
At one end make a circle 5.5 cm (2.125 in) in diameter. The wire should be
manipulated so the handle extends at a right angle from the center of the
circle for 56 cm (22 in). Stretched rubber bands bisecting the wire
circle are spaced around the circumference until it is largely covered by
rubber bands overlapping at the center.
7. Thermometer, 0-100°F.
3.^.3.5 Procedure (Modified from Bouyoucos, 1951)—
1. Weigh 50 g (oven-dried at 105°C overnight) of a fine textured or 100 g of
coarse textured (90-100$ sand) soil and place in a shaker bottle.
123
-------
2. Add 125 ml of dispersing agent and kOO ml of distilled water to
shaker bottle.
3. Cap bottle snugly and place horizontally on a reciprocating shaker
for 16 hours at 120 strokes per minute.
h. Remove bottle and bring suspension to room temperature.
5. Wash all contents of shaker bottle into a sedimentation cylinder.
6. Set cylinder in a place away from vibrations.
7. Place hydrometer in suspension.
8. Fill to lower mark (1130 ml) with distilled water for a 50 g sample.
Fill to upper mark (1205 ml) for a 100 g sample.
9. Remove hydrometer. Take plunger in one hand holding the cylinder
with the other. Strongly move plunger up and down being careful not to
spill contents of cylinder.
10. After all sediment is off cylinder bottom, carefully remove plunger
and record time immediately. NOTE: Add a drop of amyl alcohol if the
surface is covered with foam and restir the suspension if necessary.
11. Record hydrometer reading at meniscus top at the end of ko seconds.
NOTE: About 10 seconds before taking reading, carefully insert hydrometer
and steady by hand.
12. Remove hydrometer from suspension. CAUTION: Do not leave hydrometer
in suspension longer than 20 seconds as particles will settle out on its
shoulders.
13. Measure and record suspension temperature. For each °F above the
calibrated temperature of the hydrometer add 0.2 g to the reading. For
each °F below the calibrated temperature subtract 0.2 g.
lk. Record corrected hydrometer reading.
15. With the plunger, restir suspension. Take a reading at the end of
two hours. Correct hydrometer reading (see step 13) and record corrected
hydrometer reading.
16. Make 3 blanks by placing 125 ml of dispersing agent in 3 sedimentation
cylinders. NOTE: Blanks should be run for each new batch of dispersing
agent.
17. Fill cylinders two-thirds full with distilled water. Insert hydrometer
and fill cylinder to the lower mark (1130 ml) with distilled water.
18. Take hydrometer reading and temperature of suspension. Correct
hydrometer reading using step 13.
-------
3.^.3.6 Calculations—
1. Dispersing agent correction factor = Sum total of temperature corrected
hydrometer readings of blanks/3.
2. Weight corrected 2 hour reading = (Temperature corrected 2 hour
hydrometer reading) - (Dispersing agent correction factor).
3. Weight corrected Uo second reading = (Temp, corrected kO second
hydrometer reading) - (Dispersing agent correction factor).'
k. % Clay = (Weight corrected 2 hour reading/oven-dry weight of total
sample) X 100.
5. % Silt = [(Weight corrected ^0 second reading - Weight corrected 2 hour
reading)/oven-dry weight of total sample] X 100.
6. % Sand = 100 - (% clay + % silt).
3.k.k Bulk Density (Core Method)
3.^.4.1 Principles—
The soil bulk density determination is based on two measurements, a mass
measurement and a. volume measurement. The mass is measured by oven drying
the sample at 105°C until a constant weight is obtained. The bulk volume
measurement includes the space between the soil particles as well as the
space occupied by the soil particles. Bulk density, the ratio of sample
mass to sample volume, is expressed as grams per cubic centimeter (Blake,
1965).
3.^.^.2 Comments—
This method may be difficult or impractical in soil containing many rock
fragments.
A flat soil surface is prepared at the desired depth and the core sampler is
driven into the soil. If driven with a heavy hammer, the head of the tool
must be protected with a tough wooden plank or block. Care must be taken to
see that no compaction takes place so that a known volume of soil is obtained.
The sample is transferred to the laboratory and weighed while still moist.
The sample is then dried in an oven and weighed again. This sample must be
immediately placed in a desiccator after removing from the oven as the dry
sample will absorb moisture from the atmosphere (Baver, 1956, p. 180-182).
3.U.U.3 Chemicals—
Hone required.
3.h.k.k Materials—
1. Double-cylinder core sampler with steel cutting edge, driving head,
125
-------
and removable brass or aluminum sleeves.
2. Core cylinder, 7.6 cm (3 in) in diameter and 1.6 cm (3 in) in height
with 3.2 mm (0.125 in) thick walls.
3. Balance, can be read to 0.1 g.
k. Drying oven.
5. One-pint containers.
6. Air tight plastic bags.
7. Aluminum weighing pans.
8. Cloth diapers
9. Desiccator containing drierite.
3.^.^.5 Procedure—
1. Assemble double-cylinder core sampler according to the instruction
manual.
2. Prepare a'flat soil surface at depth in profile to be sampled.
3. Drive core sampler into the soil with the driving head until the soil
fills the brass or aluminum sleeve and extends slightly above it.
^. Remove driving head and twist double-cylinder core sampler.
5. Excavate soil on one side of the core sampler until the bottom of
the cutting edge can be clearly seen.
6. To insure that the contact of the core with the main soil body is
broken, run a knife across the bottom of the cutting edge. NOTE: Do this
step taking care not to disrupt the soil core.
7. Pack a cloth diaper into the top of the double-cylinder core sampler
until it rests on the top of the soil core and hold in place with one hand.
8. Gently tilt the top of the sampler towards the excavated side until the
cutting edge of the sampler is exposed. Put the other hand across the
bottom of the cutting edge to hold soil core in place. Remove core sampler
from excavation.
9. Remove the core and sleeve from sampler by raising the cutting edge and
applying gentle pressure to bottom of soil core while using the cloth diaper
to insure that the soil core does not slide or fall from the sleeve.
10. Trim any excess soil off both ends of the soil core so a flat surface
exists flush with the edges of the sleeve.
126
-------
11. Remove the soil from the sleeve ring and place in a pint container
lined with a plastic bag. Take care that no soil is lost in transfer.
12. Label the sample as to location, depth sampled and any other pertinent
information.
13. Transfer the samples to the laboratory.
Ik. Weigh a labeled aluminum pan and record the weight (A).
15. Transfer the moist soil sample to the pan and record the weight (B).
16. Place the pan with sample in an oven and allow to dry for 2k hours
at 105°C.
17. Remove the pan with sample from the oven and cool in a desiccator.
Weigh pan and contents. Record weight (C).
3.^.U.6 Calculations —
1. Bulk Density = (C - A)/3U7.5 cc, where 3^7-5 cc is the volume of the
cylinder .
2. Percent Field Moisture = ((B - C)/(C - A)) X 100.
3.^.5 Bulk Density (Saran Method)
3.4.5.1 Principle—
See l.k.k.l
3.U.5.2 Comments —
Care should be exercised when handling methyl ethyl ketone. This chemical
is toxic and flammable. An exhaust hood should be used during the mixing
of the plastic solution. Containers used for storing the solvent and the
plastic solution must have lids which provide a tight seal.
One sampling pit can be used to collect samples from several different
depths. Start at the surface and work downwards. Take a sample at the
surface and then remove all material until the horizontal layer at the
desired depth is exposed. Then take sample and repeat process until all
samples needed are collected.
When trimming a clod to the desired size, be careful not to compact or
otherwise destroy it. Careful handling of the clod is necessary until
final coatings of plastic have been applied.
3.1*. 5. 3 Chemicals —
1. Water.
127
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2. Methyl ethyl ketone
3. Dow Saran F310 solution in methyl ethyl ketone. NOTE: This solution
consists of I part Saran and 7 parts of methyl ethyl ketone. It is pre-
pared as follows: Under an exhaust hood, add 2310 ml of methyl ethyl ketone
to a 3.785 liter (l gallon) paint can. Add 330 g of Dow Saran Resin F310
to the solvent. The plastic is mixed with an air-powered or nonsparking
electric stirrer until the resin dissolves. If a high-speed stirrer is
used, the resin should dissolve in about one hour. Seal the container
tightly with lid to prevent evaporation of solvent. Care should be exer-
cised when using methyl ethyl ketone since the solvent is flammable and
its vapors mix with air to form explosive mixtures. Always work with
this solvent under an exhaust hood.
3.k.5.k Materials—
1. Tile spade and shovel.
2. Sharp knife.
3. Scissors.
k. Thread or fine wire.
5. Plastic bags (large enough to contain sample) with ties.
6. Boxes, heavy, cardboard (large enough to contain samples).
7. Cloth diapers or other suitable packing material.
8. Exhaust hood.
9. Beaker, 600 ml.
10. Balance, can be read to 0.1 g.
11. Weighing pan, aluminum or other metal.
12. Support stand with ring clamp.
13. Drying oven.
lU. Wooden rolling pin.
15- Paper (to crush clods on).
16. Sieve with 2 mm openings (10 mesh).
3.^.5.5 Procedure —
1. Dig a pit from the surface of the soil downward until a vertical cross-
section of the soil is exposed.
128
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2. Starting at the surface, work downward and remove a section of soil
larger than the clod to be studied from the face of the pit with a tile
spade.
3. Take a soil clod, about 5 cm in diameter, weighing form 30 to 150 g
from a larger piece of soil using a sharp knife to carefully cut away
excess material.
k. Carefully break or cut off all protruding points, cut off all roots
with scissors, and brush all loose materials from clod.
5. Loop thread or fine wire around clod and tie securely. Be sure to
leave a loose end of at least 50 cm (20 in) of thread or fine wire.
6. Open can containing the plastic solution. Holding the clod by the
loose thread or fine wire, immerse it in the plastic solution for 5-10
seconds.
7. Remove clod from plastic solution and suspend from a previously
prepared line (like a clothes line) for 30 minutes to allow coating to dry.
NOTE: Seal container containing plastic solution tightly to prevent
evaporation of solvent.
8. When dry, place coated sample in airtight plastic bag. Label the sample.
Record location, depth sampled, and other pertinent information in data
book.
9. Put the bag in a rigid cardboard container to prevent breaking or
crushing of clod. NOTE: To insure that sample bag will be immobilized,
use cloth diapers for packing material around the plastic bag.
10. Transport sample to the laboratory.
11. Under an exhaust hood, open can containing plastic solution. Remove
sample from plastic bag holding it by the loose thread or fine wire and
immerse it in the plastic solution for 30 seconds.
12. Remove clod from plastic solution, reseal container of plastic solution,
and hang clod on a line under the exhaust hood for 30 minutes.
13. Repeat steps 11 and 12 four more times.
lU. Fill a 600 ml beaker with approximately 350 ml of water.
15. Place beaker, with water, on a balance and weigh it to the nearest
0.1 g. Record weight (A).
16. Attach a ring clamp to the top of a support stand and position stand
so that the ring clamp extends over the beaker of water on the balance.
17. After the final coating has dried, take loose end of thread or fine
wire and lower clod into beaker of water until clod is resting on the
129
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bottom of the beaker. Record weight (B). NOTE: Do not allow loose end
of thread to fall into the beaker.
18. Loop loose end of thread or fine wire over ring clamp and slowly raise
clod off the bottom of beaker.
19. When clod is completely surrounded by water, record weight (C).
NOTE: It is extremely important that the clod is not touching any part
of the beaker and is entirely surrounded by water.
20. Remove clod from beaker and place on tray in an oven at 105°C for
1*8 hours.
21. Remove clod from oven, cool in a desiccator and weigh to the nearest
0.1 g. Record weight (D).
22. Take a knife and carefully cut plastic coating and thread or fine
wire from clod.
23. Put all clod material on a sheet of paper and crush with a wooden
rolling pin. NOTE: Be careful not to crush soft coarse fragments, but
be sure to remove all fines from coarse fragments.
2k. Pass crushed material through a 2 mm sieve.
25. Transfer all material caught on 2 mm sieve to a weighing pan and
dry in an oven at 105°C for k hours.
26. Cool weighing pan and sample in a desiccator. Weigh to nearest
0.1 g and record weight (E).
27. Discard material and weigh weighing pan. Record weight (F).
3.^.5*6 Calculations—
1. Legend:
A = Weight of beaker and water.
B = Weight of beaker, water, and moist clod.
C = Weight of beaker, water, and moist clod suspended in water.
D = Weight of oven-dry clod.
E = Weight of weighing pan and clod material greater than 2 mm in
effective diameter.
F = Weight of weighing pan empty.
V = Volume of moist clod.
130
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X = Volume of coarse fragments in clod.
2. Bulk density of clod = D/V,
Where V = (C-A)/(l.OO g/ml), the density of water is assumed to be 1.00 g/ml.
3. Bulk density of the less than 2 mm material of the clod = [D - (E - F)]/
(V - X), where: X = (E - F)/(2.65 g/ml) NOTE: This calculation assumes
that all material greater than 2 mm in effective diameter has no porosity
and has a particle density fo 2.65 g/ml.
k. Percent moisture of field sample on an oven-dry weight basis =
[((B - A) - D)/D] X 100.
3.^.6 Bulk Density (Varsol Method)
3.^.6.1 Principle—
(See 3.U.U.1)
3.^.6.2 Comments —
The nonpolar liquid, Varsol, is used because of its availability,
cheapness and absence of an offensive odor. Because of its nonpolar
nature, it can replace air trapped in pores without causing the clod
to slake like a polar liquid (water).
Clods used must hold together without breaking during routine field
and laboratory work. When samples are packed for transportation to the
laboratory, cushioning agents (i.e. diapers, styrofoam chips, crumpled
paper) should be used to reduce the chances of clod breakage.
Corrections can be made for soils containing coarse fragments using steps
28 through 31 in the procedure.
The density of each new container of Varsol should be determined by using
a clean and dry 50 ml volumetric pipet and pipetting the Varsol into a
clean and dry preweighed beaker. The weight of the Varsol is recorded
to 0.01 g. The pipetting and weighing is repeated a total of three times.
An average weight of the three readings is divided by 50 (ml of Varsol used
to determine the density).
3.U.6.3 Chemicals —
Varsol - Trade name of EXXON cleaning fluid (but can usually be purchased
from other suppliers). We have found Varsol to have a rather consistent
density of 0.77 g/cc.
3.U.6.4 Materials —
1. Digging implements (spade and shovel).
k,
2. Knife.
131
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3. Plastic bags (large enough to contain sample) with ties.
U. Containers, rigid cardboard (large enough to contain samples).
5. Drying oven.
6. Thread (or similar light weight, thin cord).
7. Balance, can be read to 0.1 g.
8. Weighing pan (preferably aluminum, but glass or other metal can
be substituted).
9. Blotting paper.
10. Desiccator apparatus, vacuum type, with hole in center of lid for
a rubber stopper (Corning 3100 or equivalent). Supported above the
bottom of the desiccator is a perforated porcelain desiccator plate
having a large center hole. A two-hole rubber stopper is placed in
the desiccator lid. In one hole is placed a 8 mm o.d., T-shaped tubing
connector. From one end of the T-connector, a short piece of tubing
with a hosecock clamp is applied to allow air back into the desiccator
after evacuation. From the other end of the T-connector, attach a length
of vacuum hose with a hosecock clamp to the vacuum source equiped with
vacuum gauge. A short piece of 8 mm o.d. glass tubing (bent at 90°) is
inserted into the second hole of the rubber stopper with the 90° bend
being outside the desiccator. A length of tygon tubing is attached to the
inside end of the glass tubingo so that when the desiccator is closed, the
tubing extends below and through the center hole of the porcelain plate.
Another piece of tygon tubing with hosecock is applied to the other end
of the glass tubing and cut to extend to near the bottom of the Varsol
container.
11. Support stand with ring clamp (aluminum rod can be substituted for
the ring clamp).
12. Beaker, 600 ml.
13. Wooden rolling pin (optional).
lit. Brown paper (optional).
3.1*. 6.5 Procedure —
1. Dig a pit from the surface of the soil downward until a vertical
cross section of the soil is exposed through the depths to be sampled.
2. Remove a large layer of soil with a spade from the face of the
sampling pit. Take a soil clod about 5 cm in diameter and weighing from
30 to 150 g from the layer of soil. NOTE: Use a knife to cut the clod
from the soil. More than one clod can be taken for testing.
132
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3. Put the sample in an airtight plastic bag. Label the sample.
Record location, depth sampled, and other pertinent information in data
book.
if. Put the bag in a rigid cardboard container to prevent breaking or
crushing the clod. NOTE: To insure that sample bag will be immobilized,
use cloth diapers for packing material around the plastic bag.
5. Transport the sample to the laboratory.
6. Weigh an oven-dry weighing pan and record the weight (A).
7. Carefully break off all protruding points and brush all loose
material from the clod.
8. Loop thread around clod and tie leaving about 50 cm (20 in) of thread
loose.
9. Place moist clod in weighing pan and weigh it to the nearest 0.1 g.
Record weight (B).
10. Place moist clod on a small square of heavy blotting paper in the
vacuum desiccator.
11. Apply grease to the ground glass surfaces of the lid and the bowl
of the desiccator.
12. Place the lid on the bowl and make a tight seal. NOTE: Make sure
the tubing extends below and through the center hole of the porcelain base
plate in the bottom of the desiccator.
13. Clamp off the hoses that lead to the supply of Varsol and air inlet.
Ik. Evacuate to a pressure of less than 0.1 bar.
15. Clamp off hose leading to vacuum source.
16. Open clamp to hose leading to Varsol and admit fluid slowly until it
completely covers sample.
17. After sample is completely covered with Varsol, allow sample to
soak for one hour.
18. Fill a 600 ml beaker with enough Varsol to cover sample completely
(approximately 350 ml) and weigh on balance to nearest 0.1 g. Record
weight (C).
19- Take a support stand and attach a ring clamp at the top of stand.
Position stand in such a manner that the ring clamp extends over the
beaker of Varsol on the balance.
133
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20. After soaking, open clamp on air inlet to allow the inside of the
desiccator to return to atmospheric pressure.
21. Remove lid of desiccator carefully. Remove clod on its "base of blotting
paper from the fluid.
22. Separate blotting paper and clod. Carefully place clod into beaker
of fluid on the balance pan and allow clod to rest on beaker bottom. Do
not let the loose end of thread fall into the beaker. Record weight (D).
NOTE: Separation of blotting paper and clod after removal of both from
Varsol will eliminate a few drops of surplus fluid from the sample, but
the drainage tension will be slight.
23. Take loose end of thread attached to clod and loop thread over the
ring clamp (or straight rod) and slowly raise the clod off the bottom of
beaker.
2k. When clod is completely surrounded by. fluid, record weight (E).
NOTE: It is essential that clod is not touching the sides or bottom
of the beaker and is entirely surrounded by the fluid.
25. Remove clod from beaker and place in weighing pan (pre-weighed in
step 6). Allow samples to air dry overnight under a hood.
26. Dry clods in an oven at 105°C for 2k hours.
2J. Remove samples from oven. Cool in desiccator and weigh to nearest
0.1 g. Record weight (F). NOTE: Steps 28 thru 31 are necessary if
bulk density and porosity of the textural particles without coarse
fragments are required.
28. Put clod on sheet of brown paper and crush with a wooden rolling pin.
NOTE: Be careful not to crush small, soft coarse fragments, but be sure
to remove all fines from coarse fragments.
29- Pass sample through a 2 mm sieve.
30. All material caught on 2 mm sieve is transferred to a weighing pan
(pre-weighed in step 6) and dried in an oven at 105°C for k hours.
31. Cool weighing pan and sample in deiccator. Then weigh sample plus
weighing pan and record weight (G).
3.^.6.6 Calculations—
1. Legend:
A = Oven-dry weight of weighing pan.
B = Weight of moist clod and weighing pan.
C = Weight of beaker and Varsol.
134
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D = Weight of beaker, Varsol, and clod.
E = Weight of beaker, Varsol, and clod suspended in Varsol.
F = Oven-dry weight of clod and weighing pan.
G = Oven-dry weight of coarse fragments contained in clod and weighing pan.
X = Volume of water in clod (equals the volume of pore space filled
with water).
Y = Volume of Varsol in clod (equals the volume of pore space filled
with Varsol).
Z = Volume of clod.
T = Volume of coarse fragments.
Density of water =1.00 g/cc.
Density of Varsol = 0.77 g/cc (see 3.^.6.2).
2. Bulk density of clod = (F - A)/Z, where:
Z = (E - C)/Density of Varsol.
3. Total pore space = X + Y, where:
X = (B - F)/Density of water; and
Y = [(D - C) - (B - A) - (F - A)]/Density of Varsol.
k. Total porosity = [(X + Y)/Z] X 100.
5. Bulk density of the less than 2 mm material in the clod.
Bulk density = (F - G)/(Z - T), where: T = (G - A)/2.65
NOTE: The coarse fragments are assumed to have no porosity; therefore,
a particle density of 2.65 g/cc is used to find the volume of the
coarse fragments. When coarse fragments have porosity the calculated
bulk density and porosity of the fines (less than 2 mm material) will be
incorrect, but bulk density and porosity of the whole clod, including coarse
fragments, will be correct.
3.4.7 Bulk Density (Sand Method)
3.^.7.1 Principle—
See 3.^.it.l
3.^.7.2 Comments—
The calculated volume of the jar and attachment remain constant as long as
135
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both maintain the same relative position to each other. If the two are to
be separated, match marks should be made to permit reassembly to this
position. The individual measured volumes of water (Q^, l^,, and Q^^) require
filling the jar and attachment repeatedly (see 3.U.7.6, no. l). Replicates
should not differ more than 3 ml between the highest and lowest volume
determined. Vibration of the sand during any of the weighings or density
determinations may cause an increase in the sand bulk density and a decrease
in accuracy. Sand bulk density (T) may change over time due to changes
in moisture content or effective graduation. Field measurements should be
run as soon as possible after the sand density (T) has been determined.
Each new bag of sand must have its sand density determined (ASTM, 197*0.
Care should be taken in excavating to minimize compaction of the soil
surrounding the hole. Any material falling from the sides of the hole
must be removed and placed with the material to be weighed. In this method,
discrimination of very thin horizons is lost; however, due to the relatively
large sample size, small errors in measuring the sand weight results in
insignificant errors (Blake, 1965).
This method is especially suited to minesoils where coarse fragments
prevent using a core sampler. The procedure also works well in coarse
textured or unconsolidated materials that cannot be tested with either
the Varsol or Saran techniques.
3.^.7.3 Chemicals—
Acetone (CH^COCHg) (optional).
3.^.7.^ Materials--
1. Template consisting of a thin, flat, metal plate 30.5 cm (12 in)
square, with a 16.5 cm (6.5 in) diameter hole in its center.
2. Sand-funnel apparatus consisting of a lower cone flanged to l6.5
cm (6.5 in) to fit the above template and a top cone section that is
threaded to receive the sand jug. A valve is located between the two
cones to control the sand flow into the density hole (specifications
in ASTM, 197^ p. 211).
3. A standard sand that is clean, dry, and free-flowing. Particle
size should be uniform passing a sieve with 0.81*1 mm openings (20 mesh)
and retained on a sieve with a 0.250 mm openings (60 mesh). (Ottawa
sand or equivalent).
iu Balance, 20 kg (UU.10 Ib) capacity which can be read to 1.0 g
(Model L-500 available from Soiltest, Inc., Evaijston, IL or equivalent).
5. Large spoon.
6. Sand scoop.
7. Brown paper (optional).
136
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8. Wooden rolling pin (optional).
9. Sieve, 2 mm openings (10 mesh).
3.4.7.5 Procedure (modified from ASTM, 1974) —
NOTE: Steps 1-16 and 3.4.7.6 no. 1-3 should be completed in the
laboratory prior to going to the field. Steps 1-8 and 3.4.7.6 no. 1
must be completed when either the jar or funnel apparatus is replaced.
Steps 9-12 and 3.4.7.6 no. 2 must be repeated for each new bag of sand.
Steps 13-16 and 3.4.7.6 no. 3 must be repeated if the funnel apparatus
is replaced.
1. Assemble apparatus and place match marks on both the jar and funnel
apparatus to permit accurate realignment in case of separation.
2. Weigh assembled apparatus empty and record weight (A).
3. Place apparatus upright. Open valve and fill with water until the
water appears over the valve.
4. Close valve and pour off excess water. Remove any water remaining in
the funnel by sponging and then wiping dry.
5. Weigh apparatus filled with water. Record weight (B). Determine
temperature of the water and record temperature (C).
6. Discard water in apparatus.
7. Repeat steps 3-6 two more times and determine the volume of the
apparatus from an average of the three weighings.
8. Thoroughly dry apparatus by the addition of acetone to absorb water,
followed by drying with a jet of moisture-free air or drying on a drying rack.
9. Place dry density apparatus upright on a firm, level surface. Close
valve and fill funnel with sand.
10. Open valve and fill apparatus. NOTE: Keep funnel at least half full
of sand during the filling procedures.
11. Close valve sharply and remove sand remaining in funnel.
12. Weigh apparatus filled with sand and record weight (D).
13. Invert apparatus and seat in template on a clean, level, planar surface.
l4. Open valve and keep open until sand stops running.
15. Close valve sharply. Weigh apparatus and remaining sand. Record
weight (E).
137
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16. Replace sand following steps 9-11.
IT. In the field, prepare the surface of the location to be tested so
that it is a level plane.
18. Place template on surface.
19. Using a large spoon, dig the test hole inside the template hole, being
careful to avoid disturbing the soil bounding the hole. NOTE: The exca-
vated hole should have a diameter equal to the diamter of the template hole.
The excavated walls of the finished hole should be as close to vertical as
possible. The hole depth should be at least T.6 cm (3 in) but not exceed-
ing l6.5 cm (6.5 in) deep.
20. Place all loosened soil in a container, being careful not to lose any
material.
21. Seat the density apparatus on the template and open the valve. After
the sand has stopped flowing, close the valve sharply.
22. Weigh apparatus and remaining sand. Record weight (F).
23. Replace as much sand as possible from the hole back into the jar, being
careful not to get contaminants in the sand from the hole.
2^. Refill apparatus with sand using steps 9-H-
25. Preweigh a weighing pan and record weight (G).
26. Place moist material removed from the test hole on the preweighed pan.
Record weight (H).
27. Place material in an oven at 105°C for l6 hours.
28. Cool in desiccator and reweigh. Record weight (l).
NOTE: Steps 29-32 are optional and are used when bulk density without
coarse fragments is required.
29. Put excavated material on a sheet of brown paper and crush with a
wooden rolling pin. NOTE: Be careful not to crush small soft course
fragments, but be sure to remove all fines from coarse fragments.
30. Pass sample through a 2 mm sieve.
31. All material caught on a 2 mm sieve is transferred to weighing pan
and dried in an oven at 105°C for k hours.
32. Cool weighing pan and sample in desiccator. Weigh sample plus
weighing pan and record weight (j).
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Calculations
1. Legend:
A = Weight of empty apparatus.
B]_ = Weight of apparatus filled with water from first weighing
(see 3.^.7.5, steps 2 through 7).
~&2 = Weight of apparatus filled with water from second weighing
(see 3.U.7.5, steps 2 through 7).
63 = Weight of apparatus filled with water from third weighing
(.see 3.^.7.5, steps 2 through 7).
C = Temperature of water.
D = Weight of apparatus filled with sand.
E = Weight of apparatus and sand excluding sand in funnel.
F = Weight of apparatus and sand excluding sand in excavated hole and
sand in funnel.
G = Weight of weighing pan.
H = Weight of moist sample and weighing pan.
I = Weight of oven-dry sample and weighing pan.
J = Weight of coarse fragments and weighing pan.
K = Volume of coarse fragments.
N^ = Weight of water required to fill apparatus on first weighing
(see 3.^.7.5, steps 2 through 7).
W2 = Weight of water required to fill apparatus on second weighing
(see 3.U.7.5, steps 2 through 7).
No = Weight of water required to fill apparatus on third weighing
(see 3.H.7.5, steps 2 through 7).
P]_ = Volume-temperature correction factor from Table 12 for first weighing
(see 3.U.7.5, steps 2 through 7).
PO = Volume-temperature correction factor from Table 12 for second weighing
(see 3.^-7.5, steps 2 through 7).
Pg = Volume-temperature correction factor from Table 12 for third weighing
(see 3.^-7.5, steps 2 through 7).
139
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TABLE 12. VOLUME OF WATER PER GRAM BASED ON TEMPERATURE
•MMBIMI^to^M^^^^H^^^MI^Hi^H^M^M^V^^^VBIM^V^V^^M
Temperature (C)
°C
12
Ik
16
18
20
Volume of
Water (P)
ml/g
l.OOOW
1.00073
1.00103
1.00138
1.00177
Temperature ( C )
°C
22
2k
26
28
30
32
Volume of
Water (P)
ml/g
1.00221
1.00268
1.00320
1.00375
1.00U35
1.00^97
Qj_ = Volume of water required to fill apparatus from first weighing
(see 3.^.7-5, steps 2 through 7).
Q2 = Volume of water required to fill apparatus from second weighing
(see 3.U.7.5, steps 2 through 7).
Qg = Volume of water required to fill apparatus from third weighing (see
3.^.7.5, steps 2 through 7).
R = Average volume of density apparatus.
S = Weight of sand required to fill apparatus.
T = Bulk density of sand.
U = Weight of sand required to fill funnel.
V = Weight of sand required to fill excavated hole and funnel.
W = Volume of excavated hole.
Y - Weight of oven-dry sample
Z = Weight of moist sample.
2. R = (Q-j^ + Q2 + Q3)/3, where:
Ql = % X P-L.
140
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Q2 = N2 X P2.
Q3 = N3 X P3, and
Nx = B1 - A.
N2 = B2 - A.
H3 = B3 - A.
3. T = S/R, where:
S = D - A.
U. U = D - E.
5. V = D - F.
6. ¥ = (V - U)/T.
T. Bulk density of soil = Y/W, where Y = I - G.
8. Percent moisture = [(Z - Y)/Y] X (100), where Z = H - G.
9. Bulk density of the less than 2 mm material in sample.
Bulk density = [Y - (J - G)]/(¥ - K), where K = (j - G)/2.65.
NOTE: The coarse fragments are assumed to have no porosity; therefore, a
particle density of 2.65 g/cc (density of quartz) is used to find the volume
of the coarse fragments. See note under 3.U.6.6.
3.k.8 Particle Density
3.^.8.1 Principle—
The relationship of the solid soil particles to their total volume excluding
the pore spaces between particles is called the particle density. It is
normally expressed as grams per cubic centimeter. The mass of the solid
particles is found by weighing and their total volume is determined by the
displacement of a liquid whose mass and density are known (Blake, 1965).
3.^.8.2 Comments—
If measurements of volumes and weights are done carefully, this method is
precise. A lack of precision in either measurement may result in serious
error.
A non-polar liquid, Varsol, is used in the procedure instead of water because
of the higher density values water gives for finely divided, active powders.
Other polar liquids (e.g. toluene, xylene, or carbon tetrachloride) can be
used, but they need special care in handling.
lUl
-------
This measurement is used to mathematically determine porosity, airspace, and
sedimentation rates for particle-size analysis. Minesoil samples are
screened through a 2 mm sieve after rolling with a rolling pin. Sample is
not ground with mortar and pestle.
3.4.8.3 Chemicals—
Varsol - Trade name of EXXON cleaning fluid (but can usually be purchased
from other suppliers). We have found Varsol to have a rather consistent
density of 0.77 g/cc.
3.^.8.U Materials—
1. Pycnometer flask with ground glass lid (modified Hubbard-Carmick,
Pyrex brand 1620 or equivalent).
2. Balance, can be read to 0.0001 g.
3. Vacuum desiccator.
3.^.8.5 Procedure (modified from Blake, 1965 and Gradwell, 1955)—
NOTE: All weights are recorded to +_ 0.0001.
1. Oven dry the less than 2 mm sample at 60°C overnight.
2. Weigh a clean, dry pycnometer flask and lid. Record weight (Wa).
3. Add about 10 g of oven-dry sample to pycnometer. Clean outside and
neck of pycnometer of any soil that may have spilled during transfer.
k. Weigh the pycnometer, including lid, and its contents. Record
weight (Ws).
5. Fill pycnometer about one-half full with Varsol, washing any soil
adhering to the neck into the pycnometer.
6. Place pycnometer into the vacuum desiccator, apply vacuum, and remove
any entrapped air. Entrapped air will be removed when all bubbling ceases.
7. Remove the pycnometer and shake gently. NOTE: Repeat steps 6 and 7
until all bubbling ceases.
8. Fill the pycnometer with enough Varsol so that when the lid is put in
place, the hole in the lid will be completely filled with Varsol.
9. Insert the lid and seat it carefully.
10. Thoroughly dry and clean the outside of the pycnometer with a dry cloth.
11. Weigh the pycnometer and its contents. Record weight (Wsv).
142
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12. Remove sample and Varsol from the pycnometer. NOTE: Thoroughly wash
pycnometer and lid with Varsol to insure removal of sample.
13. Fill pycnometer with enough Varsol so that the hole in the lid will be
filled with Varsol when the lid is seated.
Ik. Insert and seat lid. Thoroughly dry the outside with a dry cloth.
15. Weigh pycnometer filled with Varsol. Record weight (Wv).
3.^.8.6 Calculations—
Particle density (Dp) = dv (WB - Wa)/[(Ws - Wa) - (WSY - Wv)], where:
dv = Density of Varsol in g/cc (see note below).
Wg = Weight pycnometer plus sample.
Wa = Weight of pycnometer filled with air.
Wsv = Weight of pycnometer filled with sample and Varsol.
Wv = Weight of pycnometer filled with Varsol.
NOTE: The density of Varsol must be"determined for each new supply of
Varsol. Using a pipette, add exactly 50 cc to a previously tared beaker.
Record weight of the Varsol.
dv = weight (g) of Varsol/50 cc.
3.^.9 Total Porosity
3.U.9.1 Principle—
The bulk volume of a field moist soil sample contains soil particles,
moisture, and air. The portion of the bulk volume filled with moisture
and air is called pore space. Bulk density measurements (3.^.^-3.^-7) are
calculated by dividing the oven-dry weight of the mass (in grams) by the
bulk volume. This value is considerably lower than the average particle
density (3.^.8). This means that part of the bulk volume is pores filled
with air. Calculation of total porosity is done by converting data from
densities into volumes. The volume (VB) of the bulk sample is derived
from a bulk density measurement. The volume (VP) is the collective volume
occupied by solid particles and is derived from the particle density
measurement. Therefore, VP/VB is the fraction of the volume occupied by
solid particles. In this manner, total porosity can be calculated using
the equation in 3.^.9.6 (Vomocil, 1965).
3.^.9.2 Comments—
Total porosity can be measured directly if the "Varsol" method is used to
find the bulk density. The procedure and calculations are given in 3.U.6.
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Do not use an assumed particle density of 2.65 g/cm3 if carbolithic
materials are present in the sample in appreciable amounts. Measure the
particle density of this material using 3.^.8.
3.U.9.3 Chemicals—
None required.
3.k.9.k Materials—
Hone required.
3.U.9.5 Procedure—
1. Determine the bulk density using one of the following methods:
(a) 3.^; (b) 3.1*.5; (c) 3.1*.6; or (d) 3.1*.7.
2. Determine particle density using method 3.^.8. NOTE: In cases where
great accuracy is not required, use the assumed value of 2.65 g/cm-3 for
the particle density of mineral soils.
3.^.9-6 Calculations—
1. TP = Total porosity: percentage of the bulk volume not occupied by
solids.
2. BD = Bulk density of soil.
3. PD = Particle density of soil.
k. TP = [(PD - BD)/PD] X 100.
3.1*. 10 Free Swelling (Settling Volume)
3.1*. 10.1 Principle—
Swelling is an innate property of the clays. Swelling may arise in two
different ways: (l) water molecules becoming positioned between the
particles of clay; (2) water molecules becoming positioned within the
molecular structure of the clay mineral. Kaolinite and mica-like clays
will only exhibit swelling due to the former process; therefore, these
clays will have limited volume change, especially kaolinite. Clays of
the montmorillonite type exhibit extensive swelling mainly because of the
latter process. Free swelling is an important property of this type of
clay mineral (Marshall, 19^9).
3. *t. 10.2 Comments—
Step number k of 3.1*.10.5 (procedure) should be performed very carefully and
slowly so that no sample is lost. Also, step number 10 should be performed
exactly as described.
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This simple method can be used effectively to evaluate the stability of
materials. Materials exhibiting extensive swelling would be unstable on
steep slope, haul-road, etc. Also, future land use would be affected by
subh materials.
3.^.10.3 Chemicals—
Distilled water
3.^.10.^ Materials —
1. Graduated cylinders, 100 ml capacity with 1 ml graduations.
2. Powder funnels.
3. Sieve, 0.25 mm openings (60 mesh).
1*. Polypropylene wash bottle.
5. Balance, can be read to 0.001 g.
6. Pencil, yellow or any color that can be seen easily through turbid water.
7. Standard liquid limit device (Sowers, 19659 Fig- 1-1 » P- 395) adjusted
to drop a distance of 1 cm.
3.U.10.5 Procedure —
1. Weigh a 10.00 g air-dry sample of earthy material ground to pass a
60 mesh sieve.
2. Fill a 100 ml graduated cylinder to the 85 ml mark with distilled
water .
3. Put a powder funnel in the neck of the graduated cylinder.
k. Slowly add the 10.00 g of earthy material to the graduated cylinder in
several small increments. NOTE: This step must be done slowly so that all
earthy material is transferred into the cylinder without unnecessary
entrapment of air.
5. Add distilled water to the cylinder until the liquid level reaches the
100 ml mark, washing off any particles adhering to the sides of the cylinder.
6. Set cylinder aside and let stand undisturbed for 6 hours.
7. At the end of 6 hours, place cylinder on cup of liquid limit device and
turn crank 30 times at a rate of one revolution per second. NOTE: After
every five revolutions straighten cylinder without changing the rate if
necessary to keep cylinder upright.
8. Set cylinder aside and let stand undisturbed for an additional 18 hours.
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9. At the end of the prescribed time, take a yellow pencil and place it
behind the cylinder so that the pencil can only be seen by looking through
the cylinder and the material in the cylinder.
10. Starting at the top of the cylinder, lower pencil down the back of the
cylinder until the pencil can no longer be seen.
11. Record the volume at the point where the pencil cannot be seen.
3.^.10.6 Calculations—
Free swelling (settling volume) is expressed on a volume per mass basis
(cc/g).
Free swelling = volume/10.00 g air-dry sample.
3.^.11 Moisture Retention (Pressure Plate Method)
3.^.11.1 Principle—
The amount of work needed to remove water from soil is measured by the
pressure plate apparatus. This work equals the energy with which the soil
sample holds the water. In this procedure a saturated soil sample rests on
a semipermeable membrane and is subjected to controlled pressures in excess
of atmospheric pressure. A water continuum, which is at atmospheric
pressure outside the apparatus, exists from the surface of the soil sample
to the open-air side of the semipermeable membrane; therefore, the com-
pressed gas forces water out of the pores of the sample through the membrane
by way of the water continuum. Water outflow from the chamber ceases when
equilibrium has been reached (i.e., when the pressure exerted by the gas is
counteracted by the tension (negative pressure) with which the soil
particles hold onto the water). It is possible to determine directly the
moisture content of the soil at that particular tension. Normally a curve
called the moisture characteristic curve is developed by equilibrating soils
at pressures from 0 through 15 bars or higher (Richards, 1965).
3.^.11.2 Comments—
Errors in these measurements can come from many sources. Some of the
principle errors come from nonrepresentative subsamples, losses due to
evaporation during the approach to equilibrium due to a leak in the air
pressure chamber of the semipermeable membrane, pressure to temperature
effects in excess of 1°C causing hysteresis effect, failure to obtain out-
flow equilibrium, and inadequate pre-wetting of samples. Additional errors
can also come from evaporation losses when the samples are being removed
from the chamber and loss of sample during removal from the chamber; however,
these errors can be overcome as the operator becomes more proficient.
The semipermeable membrane, which may be a ceramic plate or cellulose disc,
has a definite bubbling pressure. Below bubbling pressure of these membranes,
the membrane will allow free movement of moisture from one side to the other;
however, soil particles and air are not transmitted. The membrane contains
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pores which are full of water and form the continuum from the soil sample
through the membrane to the atmosphere on the outside. When the bubbling
pressure of a membrane has been exceeded, some pores contain gas instead of
water and the gas moves freely through the membrane and pressure is lost.
After the system and the apparatus have been checked, determine which
pressure range will be measured. The USDA - SCS commonly measures moisture
retention at 1/3 and 15 bar tensions; however, the range of tensions of
prime interest for plant growth may be from 0 to 2 bars or other ranges.
For highly disturbed soils, coarse fragments sometimes constitute a major
part of the soil volume. Therefore, the particle sizes used to get a
moisture characteristic curve are not necessarily the same as for soils with
few coarse fragments. Soils sieved to contain only particle sizes of less
than 6.35 mm effective diameter are used at West Virginia University to
determine a moisture characteristic curve. Also, moisture characteristic
curves can be determined for the particle size range of 6.35 vw. to 2 mm in
effective diameter, as well as for the less than 2 mm particles (Richards,
1965).
3.^.11.3 Chemicals—
1. Distilled water.
2. Compressed nitrogen gas.
3.^.11.^ Materials—
1. Five bar pressure plate extractor (Soil Moisture Equipment Company
Catalog No. 1600 or equivalent).
2. Pressure control manifold, accuracy of control within 1/100 psi in the
0.50 psi range (Soil Moisture Equipment Company Catalog No. 700-3 or
equivalent).
3. One bar pressure plate cells (Soil Moisture Equipment Company Catalog
No. 1290 or equivalent).
U. Three bar pressure plate cells (Soil Moisture Equipment Company
Catalog No. 1690 or equivalent).
5. Soil sample retaining rings (Soil Moisture Equipment Company Catalog
No. 1093 or equivalent).
6. Connecting hose (Soil Moisture Equipment Company Catalog No. 1293 or
equivalent).
7. Nitrogen gas tank gauges - 1 for tank pressure and 1 for outflow
pressure.
8. Large spatula or small pancake turner.
9. Wax paper.
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10. Plastic teaspoon.
11. Balance, can be read to 0.01 g.
12. Drying oven.
13. Aluminum pans, for weighing samples.
±k. Laboratory notebook.
15. Desiccator, with silica gel desiccant.
3.1*. 11.5 Procedure—
NOTE: This apparatus and procedure are used for negative pressures of 0
to -3 bar. Read instrument's instruction manual before starting procedure.
1. Check pressure in the nitrogen tank.
2. Check all fittings by pressurizing system. NOTE: Take a toothbrush
and a bar of soap and mix up a soapy foam. Brush foam over each fitting
to see if there are any leaks in the system when pressurized.
3. Check ceramic plates by forcing compressed air into outlet valve. Seal
off valve and submerge ceramic plate in pan of water. If any bubbles
appear, there is a hole in the rubber gasket sealed to the plate. Repair
the leak or do not use the plate.
k. Place the ceramic plate to be used in a pan of distilled water and
soak overnight (12-16 hrs). This is done when the ceramic plates have
been dried over a period of time. If the ceramic plate has been used
for a previous determination, this prolonged soaking is not necessary.
5. Take the aluminum pans and place a soil sample retaining ring inside
the pan. Draw a line around the top of the ring so that the approximate
height of the ring is outlined on the inside of the aluminum pan. The
desired volume of subsample that would be put into the aluminum pan would
be slightly less than needed to fill the soil sample retaining ring.
6. Use a thin plastic teaspoon and lift the soil from the container and
fill the aluminum pan to the volume mark. Do two replicates in the same
manner. NOTE: Be sure that all the pans are marked with the soil sample
number.
7. After the ceramic plate has been soaked overnight, place the soil sample
retaining rings on the ceramic plate in such a fashion that a diagram can be
easily made of the set up showing the sample number for each particular ring.
8. Take the aluminum pan containing the approximate volume of soil sample
needed and carefully dump it into the proper soil sampling retaining ring
on the ceramic plate. Take the spatula or the spoon and carefully flatten
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the sample until it is level with the top edge of the soil sample retaining
ring. NOTE: Do not compact this material. Just carefully flatten by
spreading.
9. After all the soil samples have been placed on the soaked ceramic
plates, add an excess of water to the surface of the ceramic plate and
allow the samples to soak for l6 hours. NOTE: Be sure there is enough
water on the ceramic plate to allow samples to wet without removing water
from the pores of the plates.
10. Cover samples and ceramic plate with wax paper to prevent evaporation.
11. After the samples have soaked overnight (l6 hours), remove the excess
water from the surface of the ceramic plate by means of a pipette.
12. Remove the wax paper from the soil samples. Connect the outflow tube
on the ceramic plate to the outflow tube on the wall of the extractor.
13. Cover the extractor with the metal top. NOTE: Be sure that the "0"
ring seal is in place.
1^. Clamp the lid to the bottom of the extractor with clamping bolts.
Tighten the wing nuts on the clamping bolts by hand.
15. With the needle valve, the "Nullmatic" type regulator, and the coarse
adjustment regulator on the manifold all closed, pressurize the system by
means of the controls on the nitrogen tank. Turn the "Nullmatic" type
regulator valve to wide open and use the coarse adjustment valve on the
manifold to get a reading on the pressure gauge of very slightly in excess
of the desired pressure.
16. Use the "Nullmatic" type regulator to get the desired pressure
reading on the manifold's pressure gauge.
17. Slowly open the needle valve at the end of the manifold and pressurize
the pressure plate extractor. NOTE: Two hours after system is pressurized,
check pressure gauge on manifold for any final adjustment.
18. Samples that are 1 cm high can be removed any time after kQ hours
from initiation of the extraction. Some soils approach equilibrium in 18
to 20 hours; therefore, after 20 hours the outflow tube is tested period-
ically with blotter paper. If no moisture accumulates on the blotter paper
after it has been held against the outflow tube for approximately 1 minute,
equilibrium has been reached and the extraction can be stopped.
19. Clean aluminum pan previously used. Oven dry, cool in desiccator, and
weigh to nearest 0.01 g. Record weight (A)..
20. Put a piece of tubing over the outflow tube and clamp the tubing off
with a pinch clamp. Shut the pressure source off, then drain the system of
compressed gas slowly by using the coarse adjustment valve on the manifold.
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21. After the system has been drained of compressed gas, disconnect the
hose leading to the extractor. NOTE: This will insure that the extractor
is no longer pressurized.
22. Remove the clamping bolts and extractor lid.
23. Remove the samples one at a time and place in weighed aluminum pans.
2k. Quickly weigh the aluminum weighing pan and the sample. Record
weight (B).
25. Place samples in the drying oven at 105°C. Allow samples to dry
overnight. x
26. Remove samples from drying oven and place in a desiccator filled with
silica gel desiccant. Allow samples to cool.
27. Weigh samples and weighing pan. Record weight (C).
28. Discard sample.
29. Make sure that the pressure at which the extraction was carried out
is recorded in the laboratory notebook.
3.^.11.6 Calculations—
1. Legend:
A = Weight of aluminum weighing pan.
B = Weight of moist sample and aluminum weighing pan.
C = Weight of aluminum weighing pan and oven-dry sample.
2. Percent moisture = [(B - C)/(C - A)] X 100.
3.^.12 Moisture Retention (Pressure Membrane Method)
3.^.12.1 Principle—
See 3.U.11.1
3.4.12.2 Comments—
See 3.U.11.2
3.^.12.3 Chemicals—
1. Distilled water.
2. Compressed nitrogen gas.
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3. U. 12. it Materials—
1. Pressure membrane extractor (Soil Moisture Equipment Company Catalog
No. 1000 or equivalent).
2. Pressure control manifold, 0-225 psi range vith Mercury Differential
Regulator (Soil Moisture Equipment Company Catalog No. 700-1 or equivalent),
3. Torque wrench and socket (Soil Moisture Equipment Company Catalog No.
1090 or equivalent).
k. Two connecting hoses (Soil Moisture Equipment Company Catalog No. 1091
or equivalent).
5.- Soil sample retaining rings (Soil Moisture Equipment Company Catalog
No. 1093 or equivalent).
6. Cut cellulose membrane discs (Soil Moisture Equipment Company Catalog
No. 1096 or equivalent.
7. Two nitrogen gas tank gauges - one for tank pressure (0-U,000 psi) and
one for outflow pressure (0-500 psi).
8; Large spatula or small pancake turner.
9. Wax paper.
10. Plastic teaspoon.
11. Balance, can be read to 0.01 g.
12. Drying oven.
13. Aluminum pans, for weighing samples.
1^. Laboratory notebook.
15. Desiccator, with silica gel desiccant.
3.^.12.5 Procedure—
NOTE: Read instrument's instruction manual before starting procedure.
1. Place a cut cellulose membrane disc in a pan of distilled water and
allow disc to soak for at least 30 minutes.
2. Check pressure in the nitrogen tank.
3. Check all fittings by pressurizing system. NOTE: Take a toothbrush
and a bar of soap and mix up a soapy foam. Brush foam over each fitting
to see if there are any leaks in the system when pressurized.
151
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U. Take the aluminum pans and place a soil sample retaining ring inside
the pan. Draw a line around the top of the ring so that the approximate
height of the ring is outlined on the inside of the aluminum pan. The
desired volume of subsample that would be put into the aluminum pan would
be slightly less than needed to fill the soil sample retaining ring.
5. Use a thin plastic teaspoon and lift the soil from the container and
fill the aluminum pan to the volume mark. Do two replicates in the same
manner. NOTE: Be sure that all the pans are marked with the soil sample
number.
6. Remove the screen drain plate from the base of the pressure membrane
extractor. Clean the screen to remove all soil grains that might puncture
the membrane. Wet screen drain plate with distilled water and be sure that
the drain hole is open.
7. Place the screen drain plate in its proper position. Remove the
cellulose membrane disc from the water and place it on the screen drain
plate. NOTE: The membrane should completely cover the screen drain plate.
Arrange the membrane so there is a minimum of wrinkling. The membrane can-
not be handled in this manner when it is dry because cracking will occur.
8. Place an "0" RING on the cellulose membrane. Put the standard cylinder
(16 mm high) on top of the "0" RING. NOTE: Be sure that the "0" RING is in
the lower groove of the standard cylinder and that the air-entry is pointing
to the back of the pressure membrane extractor where the PM Hinge is mounted.
9. Latch the turn buttons (eccentric clamping screw assembly) into the
grooves on the outside of the standard cylinder and tighten wing nuts.
NOTE: The turn buttons hold everything in place when the samples are left
to soak overnight.
10. Place soil sample retaining rings on the membrane. Draw a diagram of
the arrangement of the rings on the membrane using the air-entry port as a
guide. NOTE: A sample number is shown on the diagram for each soil sample
retaining ring.
11. Attach a short piece of rubber tubing to the outflow tube on the
bottom of the screen drain plate. Close off the outflow tube by attaching
a pinch clamp to the rubber tubing.
12. Take the aluminum pan containing the approximate volume of soil sample
needed and carefully dump it into the proper soil sampling retaining ring
on the membrane. Take the spatula or the spoon and carefully flatten the
sample until it is level with the top edge of the soil sample retaining ring.
NOTE: Do not compact this material. Just carefully flatten by spreading.
13. Add an excess of water to the surface of the membrane and allow the
samples to soak for l6 hours. NOTE: Be sure there is enough water on the
membrane to allow samples to wet without removing water from the pores of
the membrane.
152
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iM. Cover samples and membrane with wax paper to prevent evaporation.
15- After the samples have soaked overnight (l6 hours) remove the excess
water from the surface of the membrane by means of a pipette.
16. Place an "0" RING in the groove on the top of the standard cylinder.
17. Depress the PM hinge, put the lid in place and close the cell. NOTE:
Be sure that the rubber diaphragm is between the lid and the top "0" RING
before closing the cell.
18. Bolt the pressure membrane extractor shut using a torque wrench to
tighten the bolts uniformly. A torque of 25 foot-pounds is usually adequate
for air pressure up to 15.5 bars (225 psi).
19. The connecting hose coming from the mercury differential regulator is
attached to the air-entry port on the side of the standard cylinder.
20. The other connecting hose is attached to the air-entry port on the
top of the lid.
21. Remove pinch clamp from rubber tubing on outflow tube on bottom of
pressure membrane extractor. Put 100 ml beaker under outflow tube and
catch excess water.
22. Pressurize the system up to the first regulator on the manifold by
turning the tank regulator on. Set the gas pressure in the line 2 bars
(29 psi) higher than the desired cell pressure.
23. Open the bypass valve on the mercury differential regulator.
2U. Admit gas into the cell slowly using the regulator on the manifold
until the desired pressure is attained.
25. After about 2 hours, or when the outflow rate has decreased appreciably,
close the bypass valve at the top of the "U" tube and open the exhaust valve
on the air pressure test gauge side of the manifold. When gas is heard
bubbling past the mercury in the "U" tube, close the exhaust valve and
readjust the gas pressure using the first regulator on the manifold. NOTE:
The membrane should be tested for leaks by submerging the rubber tubing
connected to the outflow tube in a beaker of water. If there is rapid
bubbling and/or a hissing of gas can be heard, then there is a leak in the
membrane. The gas should be shut off and the procedure started again using
a new membrane.
26. Check the pressure gauge reading after a few hours and readjust the
gas pressure if needed.
27. Samples that are 1 cm high can be removed any time after U8 hours
from initiation of the extraction. Some soils approach equilibrium in 18 to
20 hours; therefore, after 20 hours the outflow tube is tested periodically
with blotter paper. If no moisture accumulates on the blotter paper after
153
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it has been held against the outflow tube for approximately 1 minute,
equilibrium has been reached and the extraction can be stopped.
28. Clean aluminum pan previously used. Oven dry, cool in desiccator, and
weigh to nearest 0.01 g. Record weight (A).
29. Attach piece of tubing to the outflow tube and clamp with a pinch
clamp. Open the bypass valve and shut the pressure source off. Drain the
system of compressed gas slowly using the first regulator on the manifold.
X
30. After the system has been drained of compressed gas, disconnect the
hoses leading to the top and side of the extractor. NOTE: This will insure
that the extractor is no longer pressurized.
31. Remove the clamping bolts, extractor lid, and rubber diaphragm.
32. Remove the samples one at a time and place in weighed aluminum pans.
33. Quickly weigh the aluminum weighing pan and the sample. Record weight
(B).
3^. Place samples in the drying oven at 105°C. Allow samples to dry over-
night.
35. Remove samples from drying oven and place in a desiccator filled with
silica gel desiccant. Allow samples to cool.
36. Weigh samples and weighing pan. Record weight (C).
37. Discard sample.
38. Make sure that the pressure at which the extraction was carried out is
recorded in your laboratory notebook.
3.^.12.6 Calculations'—
1. Legend:
A = Weight of aluminum weighing pan.
/
B = Weight of moist sample and aluminum weighing pan.
C = Weight of aluminum weighing pan and oven-dry sample.
2. Percent moisture = [(B - C)/(C - A)] X 100.
3.5 MICROBIOLOGICAL METHODS
3.5.1 Summary
Early soil microbiologists developed and published original versions of the
154
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procedures described in this publication. These procedures were used in
soil investigations by their contemporaries and later soil microbiologists
the vorld over. The data obtained have played an important role in our
continual quest to unravel the mysteries of the soil.
These procedures, on the whole, are simple, easy to use, and require a
minimum of equipment. Because they were developed years ago, none of the
so-called "modern sophisticated" laboratory apparatus is involved.
/
These procedures were used in minesoil or strip mine spoil investigations
over a 15-year period. Some were chosen because no better method was
available, or because of a lack of equipment. These generally simple
methods used in studying minesoils have again played an important role as
they did earlier on conventional soils.
Though mainly simple procedures, careful planning, careful work, and a
conscientious worker are basic requirements. A technician can be trained
to perform the routine laboratory work described. Complex biological
interpretations of these laboratory measurements in relation to field
problems should include a person knowledgeable in soil microbiology.
3.5.2 Buried Slide Technique
3.5.2.J. Principle—
This technique was developed independently by both Cholodony (1930) and
Rossi et al. (1936). It is a simple procedure and provides useful infor-
mation concerning the microbes, particularly to their spatial relationships
to each other, plant roots, debris, and soil particles. If the organisms
remain intact, observations may be made of colony characteristics, feeding
of organisms on materials, and response of organisms to environmental
factors, such as water films (Frederick, 1965).
3.5.2.2 Comment s —
The method is not quantitative but can be used to show microbial differ-
ences among various treatments of a native soil or minesoil. Burying two
or more slides in each minesoil and/or treatment and removing one from each
at weekly intervals will yield information on relative abundance and
associations of the microbes.
Often the actual microorganism is no longer attached to the slide, but
after staining, the size, shape, and location of the missing entity is
revealed by stain deposition. This often reveals locations where organic
debris and sometimes soil aggregates have been in contact with the slide.
Some determination of individual organisms can be made by placing the slide
flat on the surface of an agar medium plate. The plate is incubated 2-3
hours, the slide aseptically removed, then incubation continued for at least
2k hours. This procedure will require duplicate slides, as a slide used in
this manner is no longer useful for staining and microscopic observation and
most organisms on a stained slide are dead.
155
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One familiar with bacteria, f ungi, actinomyces and diatoms, for example,
will find the interpretation of the microscopic examination of a stained
contact slide much easier than one without such familiarity. The technique
is more useful when used in conjunction with other microbial methods for
soil microbial studies than when used alone.
3.5.2.3 Chemicals— •
NOTE: All chemicals must be ACS Certified pure grade.
1. Phenol (CgH^OH),
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16. Pan. NOTE: Any pan that will hold the cups can be used.
3.5.2.5 Procedure (modified from Allen, 19^9; Wilson and Hedrick, 1957a;
Frederick, 1965)—
1. Place a circle of filter paper, cut to fit exactly, on the brass
perforated bottom of a Hilgard cup, and moisten the filter paper.
2. Weigh the complete unit. Record weight (A).
3. Fill the cup with air-dried minesoil.
U. Compact the minesoil by dropping the cup 10 times through a distance
of approximately 3 cm (l in).
5. Level the soil surface with a spatula.
6. Weigh cup and minesoil. Record weight (B).
7. Lay two glass rods on the bottom of the pan.
8. Place the cup of minesoil on glass rods.
9. Add water to the pan to reach about half cup height.
10. Allow the soil to become saturated and remain in pan and water for
2U hours.
11. Remove cup, carefully wipe outside cup surfaces and underneath bottom
to remove adhering water.
12. Weigh the cup with the soil in a saturated condition. Record weight
(C).
13. Place cup in drying oven for 2U hours at 105°C.
lk. Cool in desiccator and weigh immediately. Record weight (D). Remove
soil, brush cup and filter paper free of soil and weigh immediately.
Record weight (E).
15. Calculate soil moisture of the air-dried soil as well as the water
holding capacity (see 3.5.2.6).
16. Prepare glass microscope slides by cleaning them thoroughly. If
desired, flame slides just before use to insure sterility. NOTE: It is
desirable to use new slides.
17. Pass samples through 2 mm hardware cloth sieve to remove the rocks
and pieces of coal.
18. To 3 tumblers containing 150 g (oven-dried at 105°C for l6 hours)or some
constant weight of soil, add the following: (First tumbler) no treatment -
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control; (Second tumbler) soil thoroughly- mixed with 0.5$ autoclave-sterilized
ground straw; (Third tumbler) soil thoroughly mixed with 0.5$ autoclave-
sterilized ground alfalfa.
19. Bring the soil moisture to 50$ of the sample's water-holding capacity
in the glass containers. Add slightly more so the treatment material will be
moistened without diminishing the 50$ water-holding capacity.
20. Insert carefully the prepared glass slides (2 per tumbler) vertically
into the soil leaving about 13 mm (0.5 in) of each slide above the surface.
21. Press soil gently against slide.
22. Weigh tumbler, sample, and slides.
23. Cover tumblers with paper caps to prevent excessive evaporation, but
not to exclude aeration.
2k. Incubate soil tumblers at room temperature for one week.
25. Add water during incubation (about twice a week) to replace that
lost by evaporation. NOTE: Add water until weight of sample and tumbler
is same as weight found in step 22.
26. After incubation remove soil from only one side of one slide using a
spatula. NOTE: Gently break the slide away from the soil without sliding
the slide.
27. Remove large clumps of sand and soil from the slide surface to be
observed by means of a dissecting needle or some small sharp pointed
instrument.
28. Air dry slide.
29- With the aid of a small gentle stream of water, remove excess soil from
the undisturbed side until only a thin film remains.
30. Clean disturbed side with a damp cloth. NOTE: This is the side that
will not be stained.
31. Air dry slide.
32. Fix slide by passing it over a bunsen burner at low flame four or five
times. Do not cook. This "fixes" the material on the slide reducing the
likelihood of loss during the staining procedure.
33. Place the fixed slide over a steam bath (or beaker of boiling water).
Flood slide for 6 to 10 minutes with phenolic rose bengal. NOTE: Avoid
drying slide by adding stain as needed.
3^. Remove excess stain by washing the slide gently with water until no
more stain is removed.
158
-------
35. Air dry slide.
36. Examine the slide microscopically using a 10X or 15X eyepiece with a
97X oil immersion objective. CAUTION: Avoid scratching oil immersion
objective by making sure that all soil particles have been removed from
the slide.
37- Continue incubation of second slide for another week. Examine slide
in identical manner.
38. Examine at least 5 fields per slide.
39- Make drawings of representative fields. Arrange the drawings in two
rows so that a comparison of the slides per treatment can be readily
observed.
3.5.2.6 Calculations—
1. Legend:
A = Weight of cup and moist paper.
B = Weight of cup, moist paper, and air-dried soil.
C = Weight of cup, moist paper, and saturated soil.
D = Oven-dry weight of cup, paper, and soil.
E = Oven-dry weight of cup and paper.
. S = Weight air-dry soil.
T = Weight saturated soil.
U = Weight oven-dry soil.
V = Weight water in air-dry soil.
W = Weight water in saturated soil (water loss).
X = Percent moisture in air-dry soil.
Y = Percent water-holding capacity of soil.
Z = Grams of water per 100 g oven-dry soil needed to make 50$ water-
holding capacity.
2. S = B - A.
3. T = C - A.
Ij. U = D - E.
159
-------
5. V = S - U.
6. W = T - U.
7. X = (V/U) X 100.
8. Y = (W/U) X 100.
9. Z = Y/2.
3.3.3 Total Microbial Count (Agar-Plate Method)
3.5.3.1 Principle—
When a soil dilution is dispersed in appropriate agar medium and incubated
under favorable conditions, discrete and macroscopically visible colonies of
microorganisms -will develop. Calculations using the number of colonies
developing on the agar will give the "total count." The total count
obtained, however, is only a fraction of the total number of microbes
present. If the conditions are uniform throughout, relative if not absolute,
microbial populations can be counted successfully (Clark, 1965).
3.5.3.2 Comments—
The agar-plate method is highly empirical. Care must be taken of details
in the technique if individual workers are to obtain comparable results.
Soil samples should be processed the same day they are collected in their
natural, undried condition. Drying of the soil reduces the total count,
whereas storing moist samples at room temperature more than one day
increases the total count.
Primary soil sample dilutions should be withdrawn within ten minutes after
shaking. Rapid multiplication of organisms may result if counting is
delayed. All samples should be withdrawn from the middle of the suspension
immediately after vigorous hand shaking, since soil particle settling tends
to move microorganisms to the bottom of the suspension. Care should be
taken not to count soil particles that have settled from the solution as
colonies.
The melted medium must be cooled to a temperature of h2° to 1*5°C before
mixing with the soil, as some of the organisms are killed at higher
temperatures. If the flask containing the melted medium is too hot when
touched to the cheek, it's too hot for microorganisms.
Although the procedure uses soil-extract agar, egg-albumen, or yeast-
extract agar can be used (Clark, 1965).
3.5.3.3 Chemicals—
NOTE: All chemicals must be ACS Certified pure grade..
160
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1. Soil-extract (Lockhead, 19^0): Mix the following: 1000.0 g of fertile
soil and 1500.0 ml of distilled water. Autoclave mixture for 30 minutes at
15 psi. After partial cooling and settling, filter suspension using a
Buchner funnel, filter-aid, and medium-grade filter paper. If extract
cannot be filtered easily in this way, pour turbid soilrwater suspension
into a 2 liter graduated cylinder and let stand in a refrigerator at h°C
overnight. Settling and clearing will usually result.
2. Soil-extract agar (Lockhead, 19^0): Mix 20.0 g agar, 0.5 g dipotassium
phosphate (K2HPOi|), and 0.1 g of dextrose with 1000.0 ml of soil-extract.
Adjust pH to between 6.8 and 7.0 with 3 N HC1 or 3 N. NaOH. Sterilize medium
by autoclaving at 15 psi for 15 minutes.
3. Egg-albumen agar (Waksman and Fred, 1922): Dissolve 0.25 g of egg
albumen in 10 ml of 0.1 1J NaOH. Add 15.0 g agar, 1.0 g dextrose, 0.5 g
dipotassium phosphate (K^HPOl,.), 0.2 magnesium sulfate (MgSOij/TH^O), a trace
amount of ferric sulfate ^62(30^)3), and 1000.0 ml of distilled water.
After a preliminary heating of the medium, adjust pH to 6.8 with 3 N. HOT or
3 N. NaOH. Sterilize medium by autoclaving for 30 minutes at 15 psi.
U. Yeast-extract agar (Stevenson and Rovatt, 1953): Mix 15.0 g agar, 1.0 g
dextrose, 1.0 g sodium chloride (NaCl), 0.01 g ferric chloride (FeClj),
1.0 g yeast extract, and 1000.0 ml distilled water. Adjust pH to 6.8 with
3 N. HC1 or 3 N. NaOH. Sterilize medium by autoclaving for 30 minutes at
15 psi.
3.5.3.*+ Materials —
1. Bottle, French square, 237 ml (8 oz) with caps. NOTE: 8 required per
sample.
2. Three dozen spherical glass beads of 2 mm (0.079 in) diameter.
3. Autoclave, steam, capable of holding 15 psi and 121°C.
k. Sieve, 2 mm (10 mesh) openings.
5. Shaker, horizontal reciprocating type, 6.3 cm (2.5 in) stroke, 120
strokes per minute.
6. 10 ml pipette, sterile
7. 1 ml pipette, sterile.
8. Petri dishes, sterile. NOTE: 15 required per sample.
9. Balance, can be read to 0.01 g.
10. Humidified incubator. NOTE: A glass container with moistened paper
towels in the bottom can be used.' Place container in an oven.
161
-------
11. Quebec colony counter or a wide-field, low-power microscope.
12. Sample bags.
3.5.3.5 Procedure (Adapted from Clark, 1965)--
1. From a thoroughly mixed bulk sample, transfer about 900 g of soil to a
polyethylene bag for transport to the laboratory. NOTE: Containers must
be clean and at least sanitized so as not to harbor other microorganisms
not in the bulk sample. Avoid exposing the sample to heat or drying. If
the sample is not used that day, it may be stored in a closed container
(pinholed for aeration) at U°C for 1 or 2 weeks without serious detriment.
2. Pass entire sample through a 2 mm sieve.
3. Mix sample thoroughly.
h. Withdraw a 10 g subsample and weigh. Record weight (A). Oven dry
subsample in weighing container, cool in desiccator, and reweigh. Record
weight (B). Determine soil moisture.
5. Put approximately 3 dozen spherical glass beads and 95 ml of water in a
237 ml screw cap bottle. NOTE: The purpose of the beads is to facilitate
disintegration of soil aggregates.
6. To seven 237 ml screw cap bottles add 90 ml of water and no beads.
NOTE: More than 7 bottles will be required for dilution series if sample
is high in microorganisms. Less than 7 bottles required if low in micro-
organisms.
7. Cap all bottles.
8. Sterilize bottles by autoclaving at 15 pounds pressure for 15 minutes
and cool to room temperature prior to use. Make sure caps are loose
during autoclaving.
9. Transfer 10 g of moist soil into the bottle containing 95 ml of water
and glass beads.
10. Tightly cap bottle.
11. Shake bottle containing sample for 3 minutes in a horizontal position
in a reciprocating shaker or for an equal time by hand.
12. No longer than 10 minutes after removing the bottle from the shaker,
shake bottle vigorously by hand for a few seconds and immediately transfer
10 ml from the center of the suspension to a bottle containing 90 ml water
and no beads, using a sterile 10 ml pipette. NOTE: This establishes a
10~2 dilution.
13. Continue this dilution process by similarly transferring 10 ml
quantities to successive bottles of 90 ml and no beads to provide a dilution
162
-------
series through 10-T. NOTE: Experience with different soils will provide
a basis for estimating whether the highest dilution will need to be no more
than 10-° or 10"7, or whether it will need to be as high as 10-8 Or 10"9.
ik. From the highest dilution prepared, transfer a 1 ml portion of the
freshly agitated suspension to each of 5 sterile petri dishes by means of
a sterile, 1 nil pipette. Shake a few times before withdrawing the 1 ml
portion.
15. Make similar transfers from the two next lower dilutions into other
dishes. Shake as above.
16. Into each petri dish, pour about 15 ml of soil-extract agar, which
previously has been steamed sufficiently to insure complete melting, and
then cooled to h2°C. NOTE: Agar media that are starting to solidify, at
about UO°C, are not suitable for pouring into plates.
17. Immediately after adding agar, cover dish and carefully rotate by hand
to swirl the agar and to insure its thorough mixing with the inoculant.
CAUTION: Do not splash medium-sample mixture on petri dish cover. If
this should occur, discard and replace.
18. Permit poured plates to stand upright until the agar has solidified.
19. Invert plates in a humidified incubator at 28°C. NOTE: Some workers
prefer 25°C; others 30°C. Do not use 37°C as is commonly the practice in
medical bacteriology laboratories.
20. Leave the plates undisturbed for k days for fast growing bacteria.
NOTE: Incubation time would depend upon type of bacteria being determined.
If slow growing bacteria are being determined, 7 days are required and
preferably 10 to lU days. Actinomycetes require 10 days. Fungi can cover
a medium if left more than 5 days. However, once a time period is estab-
lished all samples must be counted at the established period of time.
21. Remove plates from the incubator.
22. Inspect all plates prepared from a single sample to see whether a
proper dilution range has been plated and whether a proper dilution effect
is apparent. NOTE: The proper dilution effect means that a plate prepared
from a given dilution should have only approximately one-tenth as many
colonies as the plate prepared from the next lower dilution. If there
are numerous colonies on the plates or a dilution effect is not apparent,
contamination has occurred. Discard all plates and rerun.
23. If incubation plates appear satisfactory, select the plates from the
dilution at which 30 to 300 colonies have developed per plate. NOTE: (l) If
the plate from the highest dilution shows greater than 300 colonies, the
dilution has been too low. (2) If the lowest dilution shows less than 30
colonies, the dilution has been too high. In either event, discard all the
plates. (3) If one or two plates within the 30 to 300 colony range have one
or more large bacterial or fungal colonies (greater than 2 cm in diameter),
163
-------
discard such plates without counting.
2k. With the aid of a Quebec colony counter or a wide- field, low-power
microscope, count the total number of colonies on each of the three or more
remaining suitable plates.
3.5.3.6 Calculations —
1. Legend:
A = Weight moist soil.
B = Weight oven-dry soil.
2. Water loss = A - B.
3. Percent soil moisture = (Water loss/B) X 100.
1*. Total viable count per gram of the initial moist soil sample = (average
number of colonies per plate for a given dilution) X (dilution factor).
5. Grams of dry matter per gram of moist soil = B/A.
6. Total count per gram of dry soil = (count per gram of moist soil)/ (grams
of dry matter per gram of moist soil).
3.5.^ MPN of Aerobic Cellulose-Decomposing Bacteria
3. 5. U.I Principle—
The most-probable-number (MPN) method permits estimation of aerobic
cellulose-decomposing bacteria without actually counting single cells or
colonies. The method is based on the presence or absence of cellulose-
decomposing bacteria on strips of paper. A strip of paper is needed for
each dilution of a minesoil. A positive (or presence) reading indicates
that at least one (it could be several) cellulose-decomposing bacterium was
present (Alexander, 1965).
3.5.^.2 Comments —
Cellulose-decomposing bacteria must meet one of the following conditions:
(l) Bacteria must bring about a change in the medium that is easily
recognizable or (2) after the bacteria have multiplied, they must be
recognizable on the strip of paper on which they are growing.
Single cellulose-decomposing bacterial cells must be capable of growth in
the medium or the method is not reliable. That is, no growth in the medium
without cellulose source, but growth with cellulose source added.
Some quantitative changes in the original number of bacteria can occur over
a period of time, even with refrigeration. The samples should be passed
164
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through a 2.0 mm sieve to remove rocks and coal. Samples must be prepared
the same day as collected (Alexander, 1965).
3.5.^.3 Chemicals —
NOTE: All chemicals must be ACS Certified pure grade.
1. Ammonium sulfate-cellulose solution (Fred and Waksman, 1928): Mix 1.0 g
ammonium sulfate ( ( Nlty ) 2SO^ ) , 1.0 g dipotassium phosphate (K2HPO^), 0.5 g
magnesium sulfate (MgSOl|'7H20) , 2.0 g calcium carbonate (CaC03), trace
amount of sodium chloride (NaCl), and 1000.0 ml of distilled water. NOTE:
The CaCOj can be left out and a trace of FeSO^ introduced.
3.5.U.U Materials—
1. Samples sieved through 2 mm sieve from depth of 0-13 cm (0-5 in) or any
other depth range of interest.
2. Medium-sized test tubes, 150 X 18 mm (6 X 0.7 in).
3. Strips of filter paper (see 3.5.^-5, No. l).
k. Pipette, 1 ml, sterilized.
5. Microscope slides, glass, 7-62 X 2.5^ cm (3 X 1 in), sterile.
6. Microscope with 10X or 15X eyepiece and 97X oil immersion objective.
7. Autoclave, steam, capable of holding 15 psi and 121°C.
8. Rubber stoppers (to fit test tubes).
3. 5 A. 5 Procedure (Fred and Waksman, 1928) —
1. Prepare a series of medium-sized test tubes containing 5 ml of the
medium and a strip of filter paper. Part of the paper should protrude
above the surface of the medium.
2. Plug test tubes with rubber stoppers. Sterilize by autoclaving for 15
minutes at 15 psi. NOTE: Make certain stoppers are loose or they will blow
out. Fold a bit of paper and insert between tube and stopper before auto-
claving and remove after autoclaving.
3. Prepare a 10- fold soil: water dilution series, stopping at 10~9. (See
3.5.3.5 Steps 5 through 13).
k. Withdraw by sterile 1 ml pipette, 5 aliquots from the 10~9 soil
suspension. Discharge 1 ml into each of 5 test tubes containing the medium.
5. Repeat step h for the next four lower dilutions, 10~° through 10~5. NOTE:
Use lower dilutions if the number of organisms is expected to be small.
165
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6. Incubate tubes at 25°C or 30°C.
7. Examine tubes daily.
8. Presence of cellulose-decomposing bacteria will be shown by the
decomposition of the paper just at the surface of the liquid.
9. After k weeks storage, make final observations.
10. Record the number of tubes at each dilution in which growth has
occurred as positive tubes.
11. Calculate the most-probable-number (MPN) of bacteria.
3.5«^«6 Calculations (Alexander, 1965)—
1. Select as P(l) the number of positive tubes of the least concentrated
dilution in which all tubes are positive or in which the greatest number of
tubes are positive.
2. P(2) and P(3) are the next two higher dilutions.
3. Using Table 13, find the row of numbers in which P(l) and P(2) corres-
pond to the experimentally observed values.
k. Follow the row of numbers across the table to the column headed by the
observed value of P(3). NOTE: This number is the MPN of organisms in the
quantity of the original sample represented in the inoculum added in the
second dilution, P(2) dilution factor.
5. Multiply the number found in step k by the dilution factor of P(2) to
obtain the MPN for the original sample.
Example A -
Using a 10-fold dilution and 5 tubes per dilution, the following numbers of
' positive tubes were observed: 5 at 10~5; 5 at 10~6; k at 10"?; 2 at 10~8;
1 at 10-9. in this series, P(l) = 5, P(2) = U, and P(3) = 2. Table 13 gives
a value of 2.2 for a dilution series of 10~T, the dilution of P(2). Multi-
plying 2.2 times 10' gives a MPN for the original sample of 22 million
bacteria, 2.2 X 10' = 22,000,000.
6. The 95$ confidence limits for MPN values can be determined from Table lU.
Upper confidence limit at 95% level = (MPN value) X (factor from Table lit).
Lower confidence limit at 95$ level = (MPN value)/(factor from Table lU).
166
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TABLE 13. MOST-PROBABLE-NUMBERS FOR USE WITH 10-FOLD
DILUTIONS AND 5 TUBES PER DILUTION
(FROM COCHRAN, 1950)
pl
0
0
0
0
0
0
1
1
1
1
1
1
2
2
2
2
2
2
3
3
3
3
3
3
1*
1*
k
k
k
k
5
5
5
5
5
5
P2
0
1
2
3
1*
5
0
1
2
3
1*
5
0
1
2
3
1*
5
0
1
2
3
4
5
0
1
2
3
1*
5
0
1
2
3
1*
5
0
_
0.018
0.037
0.056
0.075
0.091*
0.020
o.oi*o
0.061
0.083
0.11
0.13
o. 0*1.5
0.068
0.093
0.12
0.15
0.17
0.078
0.11
O.ll*
0.17
0.21
0.25
0.13
0.17
0.22
0.27
0.31*
0.1*1
0.23
0.33
0.1*9
0.79
1.3
2.1*
Most probable
1
0.018
0.036
0.055
0.071*
0.091*
' 0.11
o.oi*o
0.061
0.082
0.10
0.13
0.15
0.068
0.092
0.12
O.Ik
0.17
0.20
0.11
O.ll*
0.17
0.21
0.21*
0.29
0.17
0.21
0.26
0.33
0.1*0
0.1*8
0.31
0.1*6
0.70
1.1
1.7
3.5
number for
2
0.036
0.055
0.071*
0.093
0.11
0.13
0.060
0.081
0.10
0.13
0.15
0.17
0.091
0.12
O.ll*
0.17
0.20
0.23
0.13
0.17
0.20
0.21*
0.28
0.32
0.21
0.26
0.32
0.39
0.1*7
0.56
0.1*3
0.61*
0.95
1.1*
2.2
5-1*
indicated
3
0.051*
0.073
0.092
0.11
0.13
0.15
0.080
0.10
0.12
0.15
0.17
0.19
0.12
O.ll*
0.17
0.20
0.23
0.26
0.16
0.20
0.2U
0.28
0.32
0.37
0.25
0.31
0.38
0.1*5
0.5l*
0.61*
0.58
0.81*
1.2
1.8
2.8
9.2
values of
1*
0.072
0.091
0.11
0.13
0.15
0.17
0.10
0.12
0.15
0.17
0.19
0.22
O.ll*
0.17
0.19
0.22
0.25
0.29
0.20
0.23
0.27
0.31
0.36
0.1*1
0.30
0.36
0.1*1*
0.52
0.62
0.72
0.76
1.1
1.5
2.1
3.5
16
P3
5
0.090
O.ll
0.13
0.15
0.17
0.19
0.12
O.ll*
0.17
0.19
0.22
0.2U
0.16
0.19
0.22
0.25
0.28
0.32
0.23
0.27
0.31
0.35
0.1*0
O.U5
0.36
0.1*2
0.50
0.59
0.69
0.81
0.95
1.3
1.8
2.5
1*.3
-
167
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Example B -
The factor for example A using five tubes with a dilution of 10-fold and a
MPN equaling 2.2 obtained from Table lU is 3.30.
Upper confidence limit at 95% level = (2.2) X (3.30).
Upper confidence limit at 95% level =7.26.
Lower confidence limit at 95% level = (2.2)/(3.3).
Lower confidence limit at 95% level = 0.67.
NOTE: New tables must be used if these particular number of tubes and
dilutions are not used. MPN has a low order of precision. Large numbers
of tubes must be inoculated for each dilution for precise estimates.
Increasing the number of tubes inoculated at each dilution or narrowing the
dilution ratio, reduces the confidence limit intervals at the 95% level.
3.5.5 Carbon Dioxide Production
3.^.5*1 Principle—
This method determines the amount of carbon dioxide produced, under laboratory
conditions, by microbial decomposition of finely ground (Uo mesh) straw
(or any other additive). The quantity of carbon dioxide produced is an
index of intensity for microbial activity. Minesoils, like other soils, have
a microbial population. Vegetated minesoils are expected to contain larger
numbers and a wider variety of microorganisms than nonvegetated minesoils
(Hedrick and Wilson, 1956; Wilson and Hedrick, 1957b).
3.5-5.2. Comments —
The simplicity of this method is the ready accessibility of the materials.
Care must be taken in preparation and standardization of the barium
hydroxide, Ba(OH)2, since exact concentration (Normality) is important
(Hedrick and Wilson, 1956; Wilson and Hedrick, 1957b).
3.5.5.3 Chemicals—
NOTE: All chemicals must be ACS Certified pure grade.
1. Calcium hydroxide (Ca(OH)p), 0.0*1 I[, saturated solution: Dissolve
1.5 g (use some excess) of Ca(OH)2 in carbon dioxide-free water (See 3.2.3.3
No. l) and dilute to 1 liter. Filter off CaC03 and protect from C02 of the
air with soda lime or ascarite in a guard tube.
2. Sodium nitrate (NaN03).
3. Calcium phosphate (CaHPOj.).
168
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TABLE Ik. FACTORS FOR CALCULATING THE CONFIDENCE LIMITS FOR THE
MOST-PROBABLE-NUMBER COUNT (FROM COCHRAN, 1950)
No. of tubes
per dilution
(n)
1
2
3
U
5
6
7
8
9
10
Factor for 95$ confidence limits with
indicated dilution ratios
2
U.OO
2.67
2.23
2.00
1.86
1.76
1.69
1.6U
1.58
1.55
k
7.1U
U.OO
3.10
2.68
2. *a
2.23
2.10
2.00
1.92
1.86
5
8.32
U.U7
3.39
2.88
2.58
2.38
2.23
2.12
2.02
1.95
10
1U.U5
6.6l
U.68
3.80
3.30
2.98
2.1k
2.57
2. U3
2.32
U. Monopotassium phosphate
5. Barium hydroxide (Ba(OH)2), 0.1 N_: Dissolve 15.75 g of Ba(OH)2 in
carbon dioxide-free water (See 3.2.3.3 No. l) and dilute to 1 liter. Filter
off BaCOo and protect from COp of the air with soda lime or ascarite in a
guard tube.
6. Hydrochloric acid (HCl), 0.1 H.
7. Phenolphthalein indicator.
3.5.5.U Materials—
1. Sieve, 2 mm openings (10 mesh).
2. pH meter (Corning model 12 or equivalent) with combination electrode.
3. Refrigeration unit.
169
-------
k. Straw, ground, kO mesh, sterilized, or other biodegradable material.
5. Griffin beaker, 50 ml.
6. Griffin beaker, 600 ml.
7. Mason jars, UJ3.2 ml (l pt).
8. Plastic cylinder, 3.8l cm (1.5 in) length.
9- Rubber stoppers.
10. Fiber board (pokerchip).
11. Metal lids, 2 piece to fit Mason jar.
12. Flasks, Erlenmeyer, 250 ml.
13. Balance, can be read to 0.1 g.
3.5.5.5 Procedure (Adapted from Hedrick and Wilson, 1956; Wilson and
Hedrick, 1957b)—
1. Collect bulk samples representing the minesoil and depth in question,
usually 0-8 cm (0-3 in).
2. Save material that will crush easily with fingers and pass through a
2 mm sieve.
3. Determine water-holding capacity (See 3.5-2.5, Steps 3 through 15).
U. Place 10.0 g of minesoil sample into a series of 250 ml Erlenmeyer
flasks.
5. Add different amounts of O.OU N Ca(OH)2 to the flasks. NOTE: 5 ml of
O.OU IT Ca(OH)2 is equivalent of 1 ton of pulverized limestone per acre.
6. Dilute to 100 ml with distilled water.
7. Add 3 drops of chloroform. NOTE: The chloroform is added to prevent
microbial activity.
//8. Stopper flasks.
9. Thoroughly shake flasks twice a day.
10. Repeat step 9 for k days.
11. Determine pH values of the suspension.
12. Note the amount of O.OU N Ca(OH)2 required for 10.0 g of minesoil to
have a pH of about 7.0.
170
-------
13. Place 100 g of minesoil into each of two 600 ml beakers.
NOTE: One beaker will have the untreated sample and the other beaker will
have the treated sample.
lU. Adjust minesoil in both beakers to a pH of about 7.0 with Ca(OH)2 using
the data acquired from step 12.
15. To one beaker, add 1.0 g of ground straw, or other additive, and
thoroughly mix.
l6. To the same beaker add nitrogen (as NaM^), phosphorus (as CaHPO^), and
potassium (as KH2PO^) at an equivalent rate of 1000 Ibs per acre of U-12-U
fertilizer and thoroughly mix.
IT. Close both ends of two 3.8l cm (1.5 in) plastic cylinders with rubber
stoppers.
18. On one end cement a small disc of fiber board (pokerchip) to each
cylinder.
19. Place a cylinder inside each of the Mason jars (incubation chambers)
with the pokerchip end up.
20. While holding the cylinder firmly against the bottom, transfer the 100 g
sample from the 600 ml beakers.
21. Bring minesoil to 50 percent water-holding capacity by the addition of
distilled and/or deionized water.
22. Shake the jar gently to level the material and then gently tap it on a
table to settle the material around the cylinder.
23. Place a 50 ml beaker containing 20 ml of 0.1 N_ Ba(OH)2 and 7 drops of
phenolphthalein on top of the pokerchip. NOTE: Ba(OH)2 is used to absorb
the COo and the phenolphthalein is used as an indicator to show if the
Ba(OH)2 was converted to BaC03 before the one day incubation period was
completed. If this occurs, quickly open the incubation chamber and replace
with a new beaker of Ba(OH)2 and note for the calculations.
2b. Close the jars with two-piece metal lids.
25. After 2k hours, remove the 50 ml beakers from the Mason jars.
26. Titrate the Ba(OH)2 with 0.1 N HC1 until it clears.
27. Make a blank for each titration. NOTE: This is necessary to determine
the amount of C02 in the stock Ba(OH)2 solution.
28. After each titration, thoroughly aerate the incubation chamber by
rapidly drawing carbon dioxide-free air into the jar for about 3 minutes.
29. Repeat steps 23 through 28 for 10 days.
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3.5.5-6 Calculations—
1. ml BaC03 = (ml Ba(OH)2 used) - (ml of HC1/2).
2. mg C02 = (ml BaC03) X (N. of Ba(OH)2 X kk).
3. Total mg C02/10 days = Sum total of mg C02 for each of the ten days.
3.5.6 MPN of Sulfur-Oxidizing Bacteria
3.5.6.1 Principle—
When sulfur is added to a minesoil, the sulfur at first oxidizes slowly.
As the soil becomes acid, sulfur begins to oxidize rapidly.
Inoculation is made in "a""medium free of any organic compounds and carbonates.
Sulfur is added as the only energy source. The bacteria convert sulfur into
sulfuric acid thus lowering the pH.
3.5.6.2 Comments—
Since many organisms will not live in acid conditions, the medium has a
reaction at about pH U.O. The sulfur-oxidizing bacteria can develop at
this low pH. The high acidity and high dilutions of the culture results in
a pure culture.
Sterilization of the medium must be by flowing steam. The sterilization
must be on 3 CONSECUTIVE days at 30 minutes each. This process is called
intermittent sterilization. The first day kills vegetated cells; the
second day kills spores that have germinated; and the third day kills any
remaining vegetated cells. NOTE: Passing steam around the medium is the
best procedure; however, an autoclave can be used if: (l) there is NO
PRESSURE BUILDUP, and (2) temperature REMAINS at about 100°C.
The medium becomes turbid as bacterial growth develops and sulfur crystals
can be seen in the medium. The medium also allows for pH determination.
3.5.6.3 Chemicals—
NOTE: All chemicals must be ACS Certified pure grade.
1. Sulfur-phosphate medium (Fred and Waksman, 1928): Mix 0.2 g ammonium
sulfate ((NHit)2SO^), 3.0 g monopotassium phosphate (KH2POij), 0.25 g magnesium
sulfate (MgSOl^7H20), a trace amount of ferrous sulfate (FeSO^-TE^O), 10.0 g
of powdered sulfur, and 1000.0 ml of distilled water. Weigh 1.0 g of sulfur
into individual 250 ml Erlenmeyer flasks. Add 100 ml of the liquid medium
to each flask. Reaction of the medium is about pH k.Q. Sterilize flasks in
flowing steam for 30 minutes on 3 CONSECUTIVE days (See 3.5.6.2).
3.5.5.^ Materials—
1. Flasks, Erlenmeyer, 250 ml.
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2. pH meter (Corning model 12 or equivalent) with combination electrode.
3. Microscope with 10X or 15X eyepiece.
U. Sieve, 2 mm (10 mesh) openings.
3.6.6.5 Procedure (Fred and Waksman, 1928)—
1. Sieve sample with 2 mm sieve.
2. Prepare 20 flasks with 100 ml of the medium.
3. Prepare a 10-fold soil:water dilution series, stopping at 10~9 (See
3.5.3.5 steps 5 through 13).
U. Withdraw by sterile 1 ml pipet, 5 aliquots from the 10~9 soil
suspension. Discharge into flasks containing medium.
5. Repeat step U for the next four lower dilutions, 10~° through 10"?.
NOTE: Use lower dilutions if the number of organisms is expected to be
small.
6. Incubate flasks at 25° to 30°C.
7. After 7, 1^, and 30 days, determine pH of flasks and note if medium has
become turbid. NOTE: It is a good practice to check the turbid medium
microscopically to determine if the turbidity is due to the presence of
sulfur-oxidizing bacteria.
8. Record the number of flasks at each dilution in which turbidity has been
observed. Record these tubes as positive tubes.
9. Determine the most-probable-number (MPN) of bacteria (See 3.5.^.6).
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SECTION U
SHORT TERM AND SIMULATED WEATHERING
U.I LABORATORY AND FIELD METHODS
U.I.I Summary
Physical and chemical changes inevitably occur in the changed environment
of disturbed materials. The methods presented here provide a basis for
estimating rate and degree of change.
A mild slaking test identifies materials that will disintegrate quickly
when left exposed at the surface of a minesoil. These materials will
provide fines in minesoil profiles.
The Physical Weathering Potential (P.W.P.) method disintegrates earth and
rock fragments unless they are strongly cemented. Materials surviving this
test should persist in loose rock flumes or valley fills. Fines measured
by this method will form under intense weathering at the surface but will
not necessarily form when rocks are covered in minesoils.
The modified Sieve Analysis after Intermediate Disaggregation (SAID) method
disaggregates rock fragments less violently than P.W.P. but more than
Standardized Slaking. Modified SAID provides an estimate of rock particles
that soil scientists commonly consider coarse fragments rather than soil
fines.
Field Weathering Plots evaluate rock stability or breakdown under exposed
outdoor conditions in a particular climate. This method standardizes what
happens on the surface of minesoils and helps to calibrate laboratory
measurements of disintegration. It can be interpreted directly into
recommended placement of disturbed materials and aids the study of
variables that cause rock stability.
Stimulated Weathering Cells provide standard laboratory conditions for
measuring rate and degree of change under favorable conditions for special
reactions. The major focus has been sulfate and acid formation from
pyritic forms of sulfur. The same approach applies to other chemical or
physical changes.
17U
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U.I.2 Standardized Slaking
k. 1.2.1 Principle—
An air-dry fragment of soil or rock when quickly submerged in water is
subjected to forces that will break it apart if the individual grains are
not firmly cemented together. The disruptive forces are caused by the
release of air trapped in the pores of the fragment. As the water moves
into the pore system, the air is compressed by surface tension causing
pressures that may became great enough to break the fragment into small
pieces.
U.I.2.2 Comments—
This method uses a mild treatment to get an index of physical weathering.
It is simple, semiquantitative, and can be done in the field as well as the
laboratory.
Many samples break into smaller pieces, but the pieces sometimes slump into
a pile and do not fall through the 6.35 mm sieve. Physical overlap and
surface tension may hold the small pieces of sample together on top of the
sieve. To overcome this problem the standard liquid limit device has been
tried and calibrated. It shakes the pieces apart and allows them to fall
through the sieve.
4.1.2.3 Chemicals—
Distilled or tap water
k.I.2.h Materials—
1. 250 ml beakers.
2. Hardware cloth, 6.35 mm (0.25 in) openings.
3. Paper clips.
H. Standard liquid limit device (Sowers, 1965, Fig. 1-1, p. 395) adjusted
to drop a distance of 1 cm.
it. 1.2.5 Procedure (Modified and updated from Smith et al., 1976)—
1. Select one or more rock fragments weighing approximately 15.0 g.
2. Cut hardware cloth to fit inside of beaker.
3. Suspend the hardware cloth in the beaker by large paper clips hooked
over the rim.
k. Fill beaker with enough water (distilled or tap) to cover sieve and
fragment to be tested.
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5. Place fragment on sieve and let sample stand undisturbed for 30 minutes.
6. Place beaker in cup of standard liquid limit device and turn crank 20
times at a rate of one revolution per second. NOTE: After every five
revolutions, straighten beaker without changing the rate if necessary to
keep the beaker upright.
7. Visually estimate the percentage of material which has fallen through
the sieve, using a scale of 0 through 10 to represent 0 to 100 percent.
U.I.3 Physical Weathering Potential
U.I.3.1 Principle—
The procedure was developed by combining features of methods by Bouyoucos
(1951), Tyner (19^0), Day (1956), and Kilmer and Alexander (19^9). Rocks
are artificially weathered by treatment with a dispersing agent while
shaking on a reciprocating shaker for l6 hours. The particle size distri-
bution of material passing a 2 mm sieve is determined by mechanical analysis.
In this procedure, materials are subjected to vigorous treatment to get a
measure of particle sizes.
U.I.3.2 Comments—
The particle size distribution can be determined by either the hydrometer
or pipet method. If the pipet method is used, be sure to read method 3.U.2
carefully before starting.
Temperature is quite important to the sedimentation procedure. Although
correction factors are given, the procedure is best carried out in a
constant temperature room or by placing the cylinders in a constant
temperature bath. Care must be taken not to touch materials retained on
the sieves with anything but a gentle stream of water during the washing
process.
If the temperature corrected hydrometer reading for a particular size
fraction equals the temperature corrected reading for the dispersing agent,
that particle size is recorded as a "trace."
U.I.3.3 Chemicals—
Dispersing agent: Instant Calgon (see 3.2.2) or dissolve 35-7 g glassy '
sodium metaphosphate (Na(P03)g) (Fisher Scientific No. S-333 or equivalent)
and 7;9U g sodium carbonate (Na2C03) in distilled water and dilute to one
liter. The Na2C03 is used as an alkaline buffer to prevent the hydrolysis
of the metaphosphate back to the orthophosphate which occurs in acidic
solutions.
Materials—
1. Bottles, French square, 1 liter (32 oz) with caps.
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2. Shaker, horizontal reciprocating type, 6.3 cm (2.5 in) stroke, 120
strokes per minute.
3. Standard soil hydrometer (ASTM 152H, with Bouyoucos scale in grams per
liter).
k. Glass sedimentation cylinders with markings at 1130 and 1205 ml levels
(Bouyoucos cylinders).
5. Balance, can be read to 0.1 g.
6. Drying oven.
7. Weighing pans.
8. Thermometer, 0-100°F.
9. Plunger (see 3.U.3.U).
10. Sieve, 2 mm (10 mesh) openings, 13 cm (5 in) diameter.
11. Sieve, 6.35 mm (0.25 in) openings, 13 cm (5 in) diameter.
12. Powder funnel, large diameter to hold 2 mm sieve.
U.I.3.5 Procedure—
1. Dry intact rock fragments, between 13 and 38 mm in diameter, overnight
in an oven set at 50°C.
2. The rock fragments are weighed (+_ 0.1 g) on a tared pan. Record as oven-
dry weight (A). NOTE: Place no more than a 100.0 g sample of sandstone
(no more than a 50.0 g sample of other rock types) in a one liter shaker
bottle.
3. Add 125 ml of dispersing agent and UOO ml of distilled water to the
bottle.
ij-. Cap bottle snugly and place horizontally on a reciprocating shaker for
16 hours at 120 strokes per minute.
5. Remove bottle and allow to cool to room temperature.
6. Put a wide-mouth powder funnel in a sedimentation cylinder and insert
the 6.35 mm sieve on top of the 2 mm sieve in the funnel.
7. Transfer sample to sedimentation cylinder by pouring suspension through
sieves. NOTE: Wash all sediment from bottle by holding bottle at a U5°
angle with mouth of bottle over center of sieve. Direct a jet of distilled
water upward into bottle, sweeping all particles out by the force of the
water stream.
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8. Carefully and thoroughly wash particles retained on sieves with a gentle
.stream of distilled water. CAUTION: Do not touch particles with anything
but a stream of water. Do not exceed two-thirds the cylinder volume
during washing.
9. Carefully remove sieves from funnel. Transfer material retained on
each sieve to a separate tared weighing pan. NOTE: To make this transfer
without losing material is important. The means of making the transfer can
be with a jet of water, tapping material gently off sieves, picking material
off by hand, etc.
10. Put weighing pan and material in oven at 105°C overnight. Weigh (+. 0.1 g)
material and record weight of greater than 6.35 mm material (B) and weight
of 6.35 to 2 mm material (C).
11. Set cylinder in a place free from vibrations.
12. Place hydrometer in suspension.
13. Fill cylinder to upper mark (1205 ml) with distilled water for a
sample between 50.0 and 100.0 g. Fill to lower mark (1130 ml) for 50.0 g
sample.
1^. Remove hydrometer. Take plunger in one hand holding cylinder with
the other. Strongly move plunger up and down being careful not to spill
contents of cylinder.
15. After all sediment is off the cylinder bottom, carefully remove plunger.
Record time.
16. Record hydrometer reading at meniscus top at the end of UO seconds.
NOTE: About 10 seconds before taking reading, carefully insert hydrometer
and steady by hand.
IT. Remove hydrometer from suspension. CAUTION: Do not leave hydrometer
in suspension longer than 20 seconds as particles will settle out on its
shoulders.
18. Record suspension temperature. For each °F above calibrated temper-
ature of the hydrometer, add 0.2 g to the reading. For each °F below
calibrated temperature, subtract 0.2 g.
19. Record corrected hydrometer reading (D).
20. With the plunger, restir suspension. Take a reading at the end of
2 hours. Correct hydrometer reading (see step 18) and record corrected
hydrometer reading (E).
21. Make 3 blanks by placing 125 ml of dispersing agent in 3 sedimentation
cylinders.
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22.' Fill cylinder two-thirds full with distilled water. Insert hydrometer
and fill cylinder to the lower mark (1130 ml) with distilled water.
23. Take hydrometer reading and temperature of suspension. Correct hydro-
meter reading using step 18 and record corrected hydrometer readings of the
blanks (Fls F2, and F3).
U.I. 3.6 Calculations—
1. Legend:
A = Oven-dry wt. of rock fragments (excluding weighing pan).
B = Oven-dry wt. of material retained on 6.35 mm sieve (excluding weighing
pan).
C = Oven-dry wt. of material retained on 2 mm sieve (excluding weighing pan),
D = Temperature corrected ^0 second hydrometer reading.
E = Temperature corrected 2 hour hydrometer reading.
F]_ = Temperature corrected reading of first blank.
FO = Temperature corrected reading of second blank.
Fo = Temperature corrected reading of third blank.
G = Dispersing agent correction factor.
2. G = (F-L + F2 + F3)/3.
3. % material greater than 6.35 mm in diameter = (B/A) X 100.
k. % material between 2 and 6.35 mm in diameter = (C/A) X 100.
5. Weight corrected 2 hour reading = E - G.
6. Weight corrected kO second reading = D - G.
7. % clay = (Weight corrected 2 hour reading/A) X 100.
8. % silt = [(Weight corrected kO second reading - weight corrected 2 hour
reading)/A] X 100.
9. % sand = 100 - (% material greater than 6.35 mm + % material between 2
and 6.35 mm + % clay,+ % silt).
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fr.l.U Modified SAID
U.I.U.I Principle—
This method uses a combination of slaking and a minimum of vigorous shaking
to decompose a rock fragment. The suspension is passed through a nest of
sieves and washed with water. The amount of material retained on each sieve
is then calculated as a percent of the total sample.
k.l.k.2 Comments—
The term SAID was coined and defined by Soil Survey Staff (1970). The
translation is: Sieve Analysis after Intermediate Disaggregation. Our
modified SAID retains the original idea of the method but changes details
to satisfy objectives of this manual.
The procedure is designed particularly for normal shales, mudstones, and
other materials which tend to break-down easily. It provides a laboratory
measurement needed to help predict field behavior and for correlation with
other methods. It is intermediate in intensity between Slaking (U.I.2)
and Physical Weathering Potential (U.I.3).
U.1.U.3 Chemicals—
1. Dispersing agent: Sodium metaphosphate (Wa(PC>3)g) available from
Fisher Scientific Company No. S-333 or Instant Calgon available from Calgon
Corporation, Pittsburgh, Pennsylvania).
2. Water, tap.
U.l.U.U Materials—
1. Sieve, 6.35 mm (0.25 in) openings, U.S. Standard, 20.3 cm (8 in)
diameter.
2. Sieve, 2 mm (10 mesh) openings, U.S. Standard, 20.3 cm (8 in) diameter.
3. Sieve, 0.1 mm (lUO mesh) openings, U.S. Standard, 20.3 cm (8 in)
diameter.
U. Balance, can be read 0.01 g.
5. Flasks, Erlenmeyer, 2 liter capacity with rubber stoppers.
6. Aluminum cake tins, 23 cm (9 in) diameter.
4.1.4.5 Procedure—
1. Rock fragments between 13 and 20 mm in diameter are air dried.
2. Take a representative sample of approximately 50 g. Weigh in tared
pan and record weight (A).
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3. Place sample in a 2 liter Erlenmeyer flask.
k. Add 1 liter of tap water and 1 heaping teaspoon (about 5 g) of dispersing
agent.
5. Gently swirl, stopper, and let stand overnight.
6. Again swirl gently to free soil from bottom of flask.
T. Rotate end for end vigorously 10 times.
8. Pass through a nest of 3 sieves with 6.35 mm, 2.0 mm and 0.1 mm openings.
9. Wash the samples left on the sieves with a gentle stream of tap water
and allow time for air drying.
10. Vigorously shake the air-dry separates from side to side on sieves for
1 minute.
11. Weigh material retained on 6.35 mm sieve in tared pan and record
weight (B).
12. Weigh material retained on 2 mm sieve in tared pan and record weight (C).
13. Weigh material retained on 0.1 mm sieve in tared pan and record
weight (D).
k.l.k.6 Calculations—
1. Legend:
A = Air-dry wt. of sample (excluding weighing pan).
B = Air-dry wt. of material retained on 6.35 mm sieve (excluding weighing
pan).
C = Air-dry wt. of material retained on 2 mm sieve (excluding weighing pan).
D = Air-dry wt. of material retained on 0.1 mm sieve (excluding weighing
pan).
2. % material greater than 6.35 mm = (B/A) X 100.
3. % material between 2 and 6.35 mm = (C/A) X 100.
k. % material between 0.1 and 2 mm = (D/A) X 100.
5. % material less than 6.35 mm = 100 - (calculation no. 2).
6. % material less than 0.1 mm = 100 - (calculation no. 2 + no. 3 + no. k).
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U.1.5 Simulated Weathering Cells
*t. 1.5.1 Principle —
Processes of chemical weathering that take place during acid generation
are: solution, oxidation, hydration, and hydrolysis, with oxidation usually
emphasized. Carrucio (1967) stated that the oxidation of pyrite was
affected by four factors: oxygen, temperature, mode of iron disulfide, and
bacteria. He refined laboratory cells to provide standard conditions for
measuring acid generation rates of selected materials. Other variables
influencing rates include exposed surface area, catalytic agents, pH, ferric
iron, and mineral species other than iron disulfide. The cells described
here provide simple control over air, temperature, moisture, and microbes.
Conditions created are relatively favorable to formation of sulfates and
related compounds. Different materials can be compared and rated. Special
treatments (i.e. lime rates) can be imposed to help answer theoretical and
practical questions.
The end products have to be removed or the rate of oxidation will decrease.
Decomposition products form coatings on particles and effectively close off
the exposed surfaces. The decomposition products are removed by leaching
the sample with distilled water at the end of each treatment cycle. Measure-
ments are then made on the leachate.
U.I. $.2 Comments —
Empirical comparisons of materials and treatments afforded by this method
may be interpreted directly into likely field behavior or may serve to
reinforce or calibrate other laboratory measurements of field experiences.
Analyses identified will give a good indication of major reactions occurring
in samples. Additional analyses will satisfy specific objectives related
to plant nutrients or toxic elements.
For each cell, the graduated cylinder, beaker, and centrifuge tubes into
which the water extract is poured should be labeled the same as the cell.
It is better to take a little time labelling everything clearly and
distinctly, than to save time and get two or three samples intermixed.
4.1.5.3 Chemicals —
1. Distilled water (H20).
2. Sodium hydroxide (laOH),l N_ stock solution : Dissolve HO.O g NaOH
(electrolytic pellets) in carbon dioxide-free, distilled water (see 3.2.3.3
No. l) and dilute to 1 liter. Protect from the atmosphere using an ascarite
guard tube.
3. Sodium hydroxide (NaOH), 0.01 N : Pipet 10 ml of 1 N NaOH into a 1 liter
volumetric flask and dilute to volume with carbon dioxide- free, distilled
water (see 3.2.3.3 Wo. l). Protect from the atmosphere using an ascarite
guard tube.
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k.l.5.k Materials—
1. Plastic shoe box. The plastic shoe box is used to make a leaching
chamber. The chamber is constructed by drilling a 6.35 ™m (0.25 in) hole in
the center of one of the short sides of the box. Reverse box and drill a
6.35 mm (0.25 in) hole at the base of the other short side in the right
hand corner. Plexiglass tubing is inserted and bonded with a nonwater-
soluble glue to the box. Be sure that the plexiglass tubing bonded to the
box is 2.5 can (l in) long with equal lengths on both the inside and outside
of box. The hole in the center is used for the entrance of dry and
moistened air. While the hole in the corner is used as an exit. The lid
should be sealed using a non-hardening putty weatherstripping.
2. Wide-mouth jar, screw lid. (Mason type) - The jar is used as a humid-
ifier. Two 6.35 mm (0.25 in) holes are drilled in the lid and copper
tubing, 2.5 cm (l in) long, is inserted and soldered in place. From the
bottom of the lid flexible plastic tubing is attached to one piece of
copper tubing and to an aerating stone, which rests on the bottom of the
bottle. The copper tubing, which is attached to the aerating stone inside
the bottle, is attached to an external air source. To the other copper
tubing insert, attach flexible plastic tubing to the inlet tube of the
leaching chamber.
3. Aerating stone.
U. Pipet, 20 ml volumetric.
5. Flexible plastic tubing (Tygon or equivalent).
6. Compressed air source.
7. Sieve, 2 mm (10 mesh) openings.
8. Graduated cylinders, 100 ml capacity, plastic or glass.
9. Microburet, 10 ml capacity, graduations in 0.02 ml (Kimax 1T110F or
equivalent).
10. Meniscus magnifier for above buret.
11. pH meter (Corning Model 12 or Equivalent), with combination electrode.
12. Wheatstone bridge, (see 3.2.18.U, no. l).
13. HACK water test kit (Model DR-EL or equivalent).
Ik. Conductivity cell, pipet type, with cell constant of 1.0 reciprocal
centimeter.
15. Beaker, 250 ml.
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1+.1.5.5 Procedure—
1. Crush sample to pass a 2 mm sieve. NOTE: Subsampling and grinding are
done according to method 3.1.2; however, after the material has been
crushed to 6.35 mm (0.25 in) size, the material is split into equal halves.
One-half is used for this weathering experiment. The other half is sub-
sampled and ground according to method 3.1.2 for chemical analyses.
2. Place 200 g of .less than 2 mm material in the specially designed cell
and spread evenly across the bottom. The sample is then thoroughly
moistened with distilled water. NOTE: At this time the cell and sample
can be inoculated with bacteria to catalyze the oxidation reaction.
3. The lid is sealed tightly to the bottom of the cell and the air line
is attached to the air source. The experiment runs in a 7 day cycle. For
the first three days, dry air is passed over the sample. Then for the next
three days, moistened air is passed over the sample by filling the wide-
mouth jar about half full with water and allowing air from the aerating
stone to pass through the water.
k. On the last day of the cycle, 200 ml of distilled water is added to
each cell. The sample is allowed to soak for one hour.
5. After soaking, the cell is drained through the plexiglass tubing at the
front of the cell into a beaker. NOTE: If the water extract is turbid,
spin the water extract down in a centrifuge. Pour off the supernatant
liquid into a graduated cylinder and set aside. With a small amount of
distilled water, resuspend the fine material in the bottom of the centrifuge
tube and pour back into its proper cell.
6. The cycle of dry air and moist air passing over the sample in the cell
is started over.
7. The water extract from each cell is measured in a graduated cylinder
and the volume recorded (A).
8. Measure the electrical conductivity (see 3.2.18.5) of the water extract.
9. A 25 ml aliquot of the water extract will be taken and used to measure
sulfate concentration using a HACK DR-EL kit. Record instrument reading of
sulfate concentration (B).
10. Measure the pH (see 3.2.2.5) of the water extract. NOTE: When the pH
of water extract is 7.0 or higher, titratable acidity is zero and steps
11 through 13 are omitted.
11. The remaining water extract is transferred to a beaker and heated to
boiling to drive off any dissolved CC^.
12. After the water extract has boiled for one minute the beaker is
transferred to a desiccator, which contains no dessicant, and allowed to
181*
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come to room temperature. NOTE: An ascarite tube is placed inside the
desiccator to remove any C02 in the air.
13. After cooling, the water extract is titrated to pH 7.0 with 0.01 N
NaOH. Record volume of titrant used (c).
U.I.5.6 Calculations—
1. Legend: «.
A = Volume of water extract.
B = Sulfate concentration (ppm).
C = Volume of titrant used.
TS = Total sulfates (mg/100 g).
TA = Titratable acidity (ppm).
DF = Dilution factor.
2. Electrical conductivity. This measurement will be recorded for each
water extract and will be plotted on a graph versus time.
3. pH. This measurement will be made on each water extract and will be
plotted on a graph versus time.
k. TS = [B X DF X (A/25)J/200, where DF = 25/volume of extract used. This
measurement will be made on each water extract. It will be plotted on a
graph versus time. Also, it will be plotted as accumulative sulfates
released versus time.
5. TA = [(C X 0.01 II) X (A/(A - 25)) X 5]. Titratable acidity will be
plotted on a graph versus time. On another graph, accumulative titratable
acidity versus time will be plotted.
h.1.6 Field Weathering Plots
fr.1.6.1 Principle—
A group of standard plots under uniform outdoor conditions constitutes a
weathering yard for that particular climate. The purpose of a weathering
yard is to provide a standard near-natural means of comparing and rating
the stability of rock or earth fragments selected to represent materials
of special interest. Standard exposure affords comparison between paired
samples and calibration of breakdown against descriptive properties,
laboratory measurements, and weather events. Periodic descriptions, photo-
graphs, and weights record sample changes over time. Special tests involve
surface placement versus shallow burial, flat versus upright orientation
of bedded samples, contact with acid versus alkaline substrate, and other
variables. This yard provides ratings that can help operators and
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regulatory people decide which rocks to choose for selective placement
for a particular purpose.
4.1.6.2 Comments'—
Care must be exercised to insure that representative samples of a rock
are selected for exposure in the weathering yard. To facilitate observa-
tions and hamper sample manipulation by rodents, vegetative growth in the
plot rows is controlled with periodic sprayings of herbicide.
Plastic fence should be periodically checked to insure their security,
especially during periods of freezing and thawing of the ground. If the
fence is not securely in the ground, the sand cushion may be lost. A sand
cushion was chosen because rodents tended to remove cushions of nylon or
cloth. A coarse (0.84 - 0.50 mm), pure silica sand is used to facilitate
the separation of the weathered particles from the cushion. Due to its
inert nature, pure silica will not markedly change size nor affect the
sample weathering.
A grid system was utilized to facilitate sample location and number. The
even numbered rows contain 25 plots each, designated "A" through "Y". The
odd numbered rows allow passage through the weathering yard and contain no
plots. Each plot is 2 X 2 m with space for four subplots designated "a"
through "d" in a clockwise direction from the upper left corner. The
weathering yard should be located away from possible flood or other damage
and in an open area where samples will not be sheltered from sun or rain
actions. Duplicate samples should be evaluated.
4.1.6.3 Chemicals—
1. Herbicide (Paraquat or equivalent).
2. Hydrochloric acid (HCl), 1 part acid to 3 parts water : Dilute 250 ml
of concentrated HCl to 1 liter with distilled water.
4.1.6.4 Materials—
1. Plastic yard trimming fence, 15 cm (6 in) high, cut in 60 cm (24 in)
lengths. A circle is formed from each length, overlapping the ends by
about 5 cm (2 in) and stapling together with 6 staples.
2. Pure silica sand, 0.84 to 0.50 mm diameter (Ottawa flint shot,
Berkeley Springs 2Z sand, or equivalent). The sand is sieved through a
nested 20 mesh (0.84 mm openings) sieve and a 35 mesh (0.50 mm openings)
sieve with a 2 minute hand shaking time. Sand retained on the 35 mesh
sieve is used on the weathering plots.
3. Sieve, 0.84 mm (20 mesh) openings, 20.3 cm (8 in) diameter.
4. Sieve, 0.50 mm (35 mesh) openings, 20.3 cm (8 in) diameter.
5. Balance, can be read to 0.01 g.
186
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6. Tile spade.
7. Metric ruler.
8. Munsell color book (available from Munsell Color Division, Kollmorgen
Corporation, Baltimore, Maryland 21218).
9. Knife.
10. Weather station (optional). Required if accurate weathering conditions
are required.
4.1.6.5 Procedure—
1. Select a 5 to 10 cm representative rock sample.
2. Weigh sample to the nearest 0.01 g.
3. Obtain a Munsell color of the matrix, streak, and any noticeable spots
or films (see 2.1.3).
k. Determine rock type (see 2.1.2) and record hardness (see 2.1.4).
5. Check for presence of calcareous material (see 2.1.5)s and other rock
features (see 2.1.6 and 2.1.7).
6. Dig a round hole with the tile spade 15 cm (6 in) in diameter and 5 cm
(2 in) deep.
7. Place prepared plastic fence in hole, placing soil around both the
inside and the outside to hold it in place. Leave the inside depth k cm
(1.5 in) below ground level.
8. Place k cm (1.5 in) of prepared pure silica sand inside the plastic
fence.
9. Place rock sample on the sand.
10. Describe samples periodically in the field using the following criteria:
a. Is it breaking down? If so, describe.
b. If cracks are developing, are they regular or irregular?
c. Have there been any color changes?
d. Are there any other unusual qualities of the sample?
11. A daily record of high and low temperature and rainfall should be
maintained.
187
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12. Carefully take intact samples into laboratory periodically for
weighing.
13. After samples have been broken down, remove them from the field, weigh
and do a hydrometer mechanical analysis (see 3.^.*0 on the less than 2 mm
fractions.
lU. At the end of a study remove the remaining resistant rocks, describe,
weigh, and report their percent weight loss.
1+.1.6.6 Calculations —
% weight loss = [(initial wt. - Terminal wt.)/Initial wt.j X 100.
188
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191
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Assoc., Washington, B.C.
195
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GLOSSARY
Acidic - Having a pH of less than 7.0
Actinomycetes - Any of numerous generally filamentous and often pathogenic
microorganisms of the family Actinomycetaceae, resembling both bacteria
and fungi.
Aerobic - Oxygen-requiring organism.
Agar - Dried polysaccharide extract of red algae used as a solidifying agent
in microbiological media.
Agricultural Limestone - A soil amendment consisting principally of calcium
carbonate but including magnesium carbonate and perhaps other materials
used to furnish calcium and magnesium as essential elements for the
growth of plants and to neutralize soil acidity. It is made by
crushing or pulverizing limestone.
Argillians - See 3.3.3.2.
Alkaline - Having a pH greater than 7-0.
Amorphous - Having no crystal structure.
Anistrophic (optical mineralogy) - Any crystal in which the optical
properties (indexes) very with respect to directions of the crystal
axes. Term includes all crystal systems except isometric and amorphous.
Anthropic - Said of an epipedon that is similar to a mollic epipedon but
in which the content of ^2^5 ^s Sweater than 250 ppm.
Argillaceous - Containing an appreciable amount of clay-size particles.
Autoclave - An apparatus using steam under pressure for sterilization.
Bacteria - Any of numerous unicellular microorganisms occurring in a wide
variety of forms, existing as either a free-living organism or parasite,
and having a wide range of biochemical, often pathogenic, properties.
Bedding Planes - Planes that mark the breaks between different rock types
or changes in color or texture within a rock type.
Biotite - A mineral of the mica group. (See 3.3.2.2 for optical properties).
Birefringence - See 3.3.2.2.
196
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Blossom - The decomposed (weathered) outcrop of a coal seam on the land
surface.
Bone Coal - Coal in which the content of earthy material is too high to be
commercially valuable; the percent of ash ranges upward from about
25 percent; bone is dull rather than bright, is both heavier and
harder than commercial coal, and is classified for this manual as the
rock type carbolith.
Canada balsam - a viscous, yellowish, transparent resin obtained from the
balsam fir and used as a mounting cement for microscopic specimens.
Carbolith - See 2.1.2.
Carbonate - A group of minerals which all contain the anion (COg)"2.
Chalcopyrite - A sulfide of copper and iron, CuFeS2.
Chert - See 2.1.2.
Chlorite - A group of clay minerals as defined by method 3.3.U.
Clay film - See clay skin.
Clay-size particles - Particles having an equivalent diameter of less than
2 microns (0.002 mm).
Clay skin (clay film) - A thin coating of well-oriented clay particles on
the surface of a soil aggregate, particle, or pore.
Collapsing minerals - A group of clay minerals whose internal structure
collapses upon heating due to the removal of interlayer waters.
Colony - A microscopically visible growth of microorganisms on a solid
culture medium.
Concretion - A hard, compact, rounded, normally subspherical mass or aggre-
gate of mineral matter generally formed by orderly and localized pre-
cipitation from an aqueous solution in the pores of a sedimentary rock
and usually of a composition widely different from that of a surrounding
rock and rather sharply separated from it. Concretions have concentric
layering about a central core.
N
Confidence limits - Either the upper or lower .value between which an actual
measurement or parameter will fall with a stated probability.
Crystal - A homogeneous, solid body of a chemical element, compound, or
isomorphous mixture having a regularly repeating atomic arrangement
that may be outwardly expressed by planar faces.
Culture - A population of microorganisms grown in a medium.
197
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Cutans - See 3.3.3.2.
Density - The weight of a substance per unit volume of water which it will
displace. Bulk density is expressed in grams per cubic centimeter.
Dolomite - Same as limestone except has substitution of magnesium for some
of the calcium, CaMg (003)2. Differs from limestone since cold dilute
HC1 will not, or only slightly, cause effervesence except when applied
to powdered sample.
Drift - See 1.1.2.
Earth worm casts - See 3.3.3.2.
Earthy material - See 2.1.2.
Epipedon - A diagnostic surface layer of soil.
Epsomite - See 2.1.7.
Extinction - The more or less complete darkness obtained in a birefringent
mineral at two positions during a complete rotation as seen with
crossed nicols using a petrographic microscope.
Fe-Al sulfates - See 2.1.7.
Ferrans - See 3.3.3.2.
Fizz - The process of a material (whether rock or soil) bubbling when
cold dilute hydrochloric acid is applied.
Flint - See 2.1.2.
Fossils - Any remains, trace, or imprint of a plant or animal that has been
preserved, by natural processes, in the earth's crust since some past
geologic time.
Fungi - Any of numerous plants including the yeasts, molds, smuts, and
mushrooms.
Glacial drift - See 2.1.2.
Gypsum - See 2.1.7.
Hardness - The resistance of a mineral to scratching (See 2.1.4 for more
detail).
Hematite - An iron oxide ^6903) mineral (See 3.3.2.2 for optical properties).
Hexagonal - One of the six crystal systems characterized by minerals having
six crystal faces resulting from three equal length horizontal axes
at right angles to a differing length central vertical axis.
198
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Highwall - The exposed face of excavated overburden and coal in a surface
mine or the face or bank of the uphill side of a contour strip mine
excavation.
Horizon - See soil horizon.
Hydrated Lime - A material made from burnt lime which consists primarily
of calcium hydroxide.
Illite - A group of clay minerals as defined by method 3.3. *K
Immersion - To cover completely with a liquid.
Incubate (incubation) - Holding cultures of microorganisms under conditions,
especially temperature, favorable to their growth.
Incubation period - The time period during which microorganisms innoculated
into a medium are allowed to grow.
Inoculum - The material containing microorganisms and used for the artifi-
cial introduction of microorganisms into a culture medium.
Intercalate - See 2.1.2.
Interference colors - See 3.3.2.2.
Isometric - One of the six crystal systems characterized by three axes that
are mutually perpendicular and of equal lengths.
Isotrophic - See 3.3.2.2.
Kaolin - A group of clay minerals as defined by method 3.3.^.
Kaolinite - A clay mineral of the kaolin group as defined by method 3.3.^.
Jasper - See 2.1.2
Limestone - See 2.1.2.
Loess - See 2.1.2.
Luster - The reflection of light from the surface of a mineral.
Macroscopic - Visible without the aid of a microscope.
Mangans - See 3.3.3.2.
Marcasite - Like pyrite, an iron disulfide, FeS2; however, differs in
crystal form.
Medium - A substance used to provide nutrients for the growth and multi-
plication of microorganisms.
199
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Mica - See 2.1.6.
Microcline - A mineral of the alkali feldspar group. (See 3.3.2.2 for
optical properties).
Microbe (Microbial) - Microscopic organism belonging to either the plant
or animal kingdom.
Microorganism - Form of life of microscopic dimensions.
Microscopic - Visible only with the aid of a microscope.
Mineral - A naturally formed chemical element or compound having a definite
chemical composition and usually a characteristic crystal form.
Mollic - Pertaining to a dark, thick epipedon having at least Q.5o% organic
carbon, a base saturation of at least 50% vhen measured at pH Tj and
less than 250 ppm Pg^S soluble in citric acid.
Monoclinic - One of the six crystal systems. Minerals in this system -will
have three unequal axes, two of which are obliquely inclined to each
other and the third is perpendicular to the plane formed by them.
Montmorillonite - A group of expanding-lattice clay minerals as defined by
method 3.3.^.
Mudrock - See 2.1.2.
Mudstone - See 2.1.2.
Munsell Color System - A color designation system that specifies the
relative degrees of the three simple variables of color: hue, value,
and, chroma. The Hue of a color indicates its relation to red, yellow,
green, blue, or purple; the Value indicates its lightness (ranges from
absolute black at 0 to absolute white at 10); The Chroma indicates its
strength (or departure from neutral of the same lightness). For example:
10YR 6/k has a color of Hue 10YR, Value 6, and Chroma k (for additional
information see 2.1.3).
Muscovite - A mineral of the mica group (see 3.3.2.2 for properties).
Nodule - A hard, compact, rounded mass or aggregate of mineral matter.
Unlike concretions, nodules do not have concentric layering.
Opaque - Said of materials that are impervious to light.
Organism - A living biological specimen.
Orthoclase - A mineral of the alkali feldspar group. (See 3.3.2.2 for
properties). •
Orthorhombic - One of the six crystal systems, characterized by three axes
200
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that are mutually perpendicular and of unequal length.
Outvash - See 2.1.2.
pH - A number!cal measure of the acidity or alkalinity. The neutral point
is pH 7.0. All pH values below 7.0 are acid and all above 7.0 are
alkaline (for more information see 3.2.2).
Plate counting - The counting of microorganisms on a microscope slide.
Pocket - A small, discontinuous occurrence or patch of mineralized material,
rock, soil, or void within a rock, stratum, or soil.
Polysaccharide - A carbohydrate formed by the combination of many molecules
of monosaccharides (e.g. starch, cellulose, glycogen).
Pores - See 3.3.3.2.
Pyrite - An iron disulfide (FeSg) mineral. (See 2.1.6 for detection and
3.3.2.2 for optical properties).
Quartz - Crystalline silica (Si02). (See 3.3.2.2 for optical properties).
Rock - Any consolidated or coherent naturally formed mass of mineral matter.
Rock chips - (a) Field - Fragments of rock expelled by a compressed air
rotary blast hole drill.
(b) Laboratory - Fragments taken from a rock used for analysis.
Rock Texture - A general physical appearance or character of a rock and the
mutual relations among the component particles or crystals; e.g. the
size, shape, and arrangement of the constituent elements of a sedimen-
tary rock.
Root channels - See 3.3.3.2.
Sand-size particles - A particle having an equivalent diameter in the range
of 0.05 to 2.0 mm.
Sandstone - See 2.1.2.
Shale - See 2.1.2.
Silt-size particles - A particle having an equivalent diameter in the range
of 0.002 to 0.05 mm.
Siltstone - A fine-grained consolidated clastic rock composed predominantly
of particles of silt grade or size. Individual grains are not visible
without magnification. Crushed wet fragments feel smooth rather than
gritty or sticky. Would fall into the mudrock or mudstone category
depending on hardness.
201
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Skeletal grains - See 3.3.3.2.
Soil - The natural bodies on the earth's surface, in places modified or
even made by man of earthy materials containing living matter and
supporting or capable of supporting plants out-of-doors.
Soil horizon - A layer within the soil profile that has characteristics
that separate it from the rest of the profile. (For additional
information on the soil horizons used in the manual, see 2.1.2).
Soil profile - A vertical section of the soil from the surface through all
its horizons.
Soil texture - The relative proportion of the various soil separates (e.g.
sand, clay, and silt) in a soil, (see 2.1.8 for additional information).
Spore - A resistant body formed by certain microorganisms; a resistant
resting cell; a primitive unicellular reproductive body.
Sterilize (Sterilization) - The killing of all forms of life.
Stokes' Law - A formula that expresses the rates of settling of spherical
particles in a fluid: V = Cr2, where V is velocity (in cm/sec), r is
the particles radius (in cm), and C is a constant relating relative
densities of fluid and particle, acceleration due to gravity, and
viscosity of the fluid.
Tension - The suction or negative pressure of soil water.
Tetragonal - One.of the six crystal systems, in which the crystals are
related to three mutually perpendicular axes, the vertical axis of
which is of unequal length relative to the two horizontal axes.
Thin section - See 3.3.3.1.
Translucent - Said of a mineral that transmits light, but is not transparent.
Transparent - Said of a mineral that is capable of transmitting light, and
through which an object can be seen.
Triclinic - One of the six crystal systems, characterized by three unequal
axes that intersect obliquely.
Texture - See rock texture or soil texture.
Till - See 2.1.2.
Umbric - Pertaining to an epipedon that is- similar to a mollic epipedon
except for having a base saturation of less than 50$, measured at a
pH of 7.
202
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Undersoil - The material (rock or unconsolidated) that directly underlies
a coal.
Vermiculite - A group of clay minerals as defined by method 3.3.^.
Viable - Living
Viscosity - The property of a substance to offer internal resistance to flow.
Water holding capacity - The smallest value to which the water content of a
soil can be reduced by gravity drainage.
203
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-78-054
3. RECIPIENT'S ACCESSION»NO.
TITLE AND SUBTITLE
FIELD AND LABORATORY METHODS APPLICABLE TO OVERBURDENS
AND MINESOILS
5. REPORT DATE
March 1978 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOH(S)
Andrew A. Sobek, William A. Schuller, John R. Freeman,
and Richard M. Smith
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
College of Agriculture and Forestry
West Virginia University
Morgantown, West Virginia 26506
10. PROGRAM ELEMENT NO.
EHB - 526
11. CONTRACT/GRANT NO.
R 803508-01-0
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio U5268
- Gin., OH
13. TYPE OF REPORT AND PERIOD COVERED
Final 1/75-12/76
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
With the growing demand for environmental assessment of a mining site, it becomes
apparent that a manual of field and laboratory procedures to study the overburden
and the resulting minesoil is necessary.
Incorporated within this manual are step-by-step procedures on field identification
of common rocks and minerals; field sampling techniques; processing of rock and soil
samples; and chemical, mineralogical, microbiological, and physical analyses of the
samples. The methods can be used by mining companies, consultant firms, and State
and Federal agencies to .insure mining efficiency, post-mining land and water quality,
and long range land use.
Inherent to these methods is the definition of terms. Many common terms are used
inconsistently even within small groups; and when multiple disciplines are involved,
communication demands that many terms must be defined for that particular purpose.
Thus, the definition of essential rock, soil, chemical, mineralogical, microbiological,
and physical terms constitute an important part of this project.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Coal Mines, *Surface Mining,
Overburden, *Chemical Properties
Weathering
*Potential Toxicity, *Minesoils,
*Neutralization Potentials,
*Available Nutrients,*Physical
Properties,*Acid-Base Account,
*Preplanning, *Analytical Prop-
erties ,*Mineralogical Properties,
*Microbiological Properties
91A
19. SECURITY CLASS (ThisReport/
Unclassified
». DISTRIBUTION STATEMENT
Release to Public
21. NO. OF PAGES
216
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
20U
U. S. GOVERNMENT PRINTING OFFICE: 1978-759-829
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