EPA 600/8-81-003
February 1981
EFFECTS OF SEWAGE SLUDGE ON THE
CADMIUM AND ZINC CONTENT OF CROPS
by
Council for Agricultural Science and Technology
Ames, Iowa 50011
Prepared at request of
Office of Research and Development
U.S. Environmental Protection Agency
Washington, D.C. 20460
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT ,
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed;by the Municipal 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.
ii
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FOREWORD
The U.S. Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health and
welfare of the American people. Noxious air, foul water, and spoiled land are
tragic testimonies to the deterioration of our natural environment. The com-
plexity of that environment and the interplay of its components require a
concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solution;
it involves defining the problem, measuring its impact, and searching for
solutions. The Municipal Environmental Research Laboratory develops new and
improved technology and systems to prevent, treat, and manage wastewater and
solid and hazardous waste pollutant discharges from municipal and community
sources, to preserve and treat public drinking water supplies, and to minimize
the adverse economic, social, health, and aesthetic effects of pollution. This
publication is one of the products of that research and provides a most vital
communications .link between the researcher and the user community.
This report evaluates the available data on the effects on plants of
single and repeated additions of cadmium (Cd) and Zinc (Zn) to soils in the
form of sewage sludge. The influence of sludge, soil, plant and climatic
factors also is addressed.
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
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PREFACE
Sewage sludge contains substantial quantities of nitrogen and phosphorus,
both of which are nutrients required by plants and are important constituents
of animal manures and commercial fertilizers. In addition to plant nutrients
and organic matter, sludge contains small but variable quantities of other un-
wanted substances, such as toxic metals, in concentrations that may be much
higher than those usually found in household wastes. Cadmium is of greatest
concern. The Office of Research and Development of the Environmental Protection
Agency requested CAST to prepare a report on the effects of sewage sludge on the
cadmium and zinc content of plants as a way of collecting the latest published
and unpublished information on this subject in a form that could be cited in
connection with proposed regulations being developed to control the application
of sludge to agricultural soils.
A task force of 25 scientists involved in research on sewage sludge was
accordingly assembled by CAST at Ohio State University February 27 to 29, 1980,
to discuss the assignment and to prepare a rough draft of a report. The task
force chairman then circulated two more drafts to task force members for review
and comment, and the CAST office circulated one more edited draft to the CAST
Editorial Review Committee and two |to task force members for further review and
comment before the final "version was reproduced for transmission to the Environ-
mental Protection Agency.
On behalf of CAST, I thank members of the task force and all the others
who gave of their time and talents to prepare this report as a contribution of
the scientific community to public understanding. Thanks are due also to
members of CAST. The unrestricted contributions they have made in support
of the work of CAST have financed the report. Task force members are reim-
bursed on request for travel and subsistence expenses they incur when partici-
pating in official CAST activities, but they receive no honoraria for their
work. Their salaries are paid by their employers.
This report is being distributed to the Environmental Protection Agency
and the media, to institutional members of CAST, and to an additional selected
list of persons. Individual members may receive a copy on request.
This report may be republished or reproduced in its entirety without
permission. If republished, credit to the authors and CAST would be appreciated.
Charles A. Black
Executive Vice President
Council for Agricultural
Science and Technology
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ABSTRACT
This report evaluates the available data on the effects on plants of single
and repeated additions of cadmium (Cd) and zinc (Zn) to soils in the form of
sewage sludge. The influence of sludge, soil, plant and climatic factors: also
is addressed. The major findings are as follows:
1. The concentrations of Cd and Zn in plants vary with (a) the species and
cultivar grown, (b) environmental and management factors, (c) soil
properties - pH is the most critical factor in controlling plant up-
take of Cd and Zn, (d) the annual and cumulative amounts of Cd and Zn
applied to soils and (e) the plant part sampled - vegetative tissues
usually show greater concentrations of Cd and Zn and greater absolute
increases in concentration of Cd and Zn from sludge applications than
do the fruit, grain or tubers.
2. Nearly all sewage sludges contain Cd and Zn at levels that will in-
crease the total concentration of Cd and Zn in soils. .
3. The availability to plants of a given quantity of sludge-borne Cd or
Zn varies- with the characteristics of the sludge.
4. Soil cation exchange capacity does not adequately reflect the
properties that control the availability to plants of Cd and Zn in
sludge-treated soils.
5. The concentrations of Cd and Zn in plants generally increase with a
decrease in soil pH. :
6. In noncalcareous-soils, the concentration of Cd and Zn in most crops
increases with increasing amounts of Cd and Zn applied.
1. In calcareous soils, the increases in Cd and Zn concentrations in
plants due to additions of these elements to soils are usually sub-
stantially less than those observed under comparable conditions in
noncalcareous soils.
8. At a given soil pH value, the concentrations of Cd and Zn in crops
after repeated annual sludge additions appear to be either approxi-
mately the same as, or less than, those resulting from a single addi-
tion of the same sludge supplying amounts of Cd and Zn equivalent to
the sum-
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9. Considerable increases in concentrations of Cd and Zn in many crops
cannot be avoided when sludges high in these metals are applied unless
annual and cumulative additions of the metals are limited and unless
the soil reaction is maintained near or above neutrality.
10. Even at a soil pH of 6.5, the Cd added in many sludges is sufficient to
increase the Cd concentrations in most crops.
VI
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CONTENTS
Overview 1
Introduction 4
Sewage sludge characteristics . 7
Cadmium and zinc in sewage sludge ........ 7
Theoretical mechanisms for retention of cadmium and zinc
in sludges 9
Crop response to cadmium and zinc additions in sludge 12
Differential uptake of cadmium and zinc by crop species 12
Differential uptake of cadmium and zinc by crop cultivars .... 13
Environmental influences on the cadmium and zinc content of crops 14
Effect of soil properties on the response of crops to cadmium
and zinc additions 16
Soil cadmium and zinc concentration ....... 16
Soil pH *. 18
Soil cation exchange capacity 20
Other soil factors 22
Extractable metals 23
Crop response to cadmium and zinc in single and repeated
applications of sludge ' . 24
Single and repeated additions of sludge-borne cadmium and zinc . . 26
Availability of sludge-borne cadmium and zinc to plants after
termination of sludge applications to soils . . 27
Literature cited 30
Tables and figures 39
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TASK FORCE MEMBERS
L. E. Sommers (Chairman of the task force), Department of Agronomy, Purdue
University
D. E. Baker, Department of Agronomy, Pennsylvania State University
T. E. Bates, Department of Land Resource Sciences, University of Guelph
J. Baxter, Metro-Denver Sewage Disposal District No. 1
C. R. Berry, U.S. Forest Service, Athens, Georgia
D. F. Bezdicek, Department of Agronomy and Soils, Washington State University
K. W. Brown, Department of Soil and Crop Sciences, Texas A&M University
R. L. Chaney, USDA-SEA-AR, Beltsville, Maryland
R. B. Corey, Department of Soil Science, University of Wisconsin
R. H. Dowdy, USDA-SEA-AR, Department of Soil Science, University of Minnesota
R. Ellis, Jr., Department of Agronomy, Kansas State University
P. M. Giordano, Soils and Fertilizer Research Branch, Tennessee Valley Authority,
Muscle Shoals, Alabama
T. D. Hinesly, Department of Agronomy, University of Illinois
T. J. Logan, Department of Agronomy, Ohio State University
Cecil Lue-Hing, Metropolitan Sanitary District of Greater Chicago
R. J. Mahler, Municipal Environmental Research Laboratory, U.S. Environmental
Protection Agency, Cincinnati, Ohio
R. W. Miller, Department of Soil Science and Biometeorology, Utah State
University
W. J. Miller, Department of Animal and Dairy Science, University of Georgia
A. L. Page, Department of Soil and Environmental Sciences, University of
California at Riverside
I. L. Pepper, Department of Soils, Water and Engineering, University of Arizona
viii
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J. A,, Ryan, Municipal Environmental Research Laboratory, U.S. Environmental
Protection Agency, Cincinnati, Ohio '
J. J. Street, Department of Soil Science, University of Florida
M. Sumner, Department of Agronomy, University of Georgia
V. V. Volk, Department of Soil Science, Oregon State University
M. D. Webber, Wastewater Technology Center, Environmental Protection Service,
Burlington, Ontario
CONSULTANT
A. M. Wolf, Department of Agronomy, Pennsylvania State University
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OVERVIEW
This report evaluates the available data on the effects on plants of
single and repeated additions of cadmium (Cd) and zinc (Zn) to soils, in
the form of sewage sludge. The influence of sludge, soil, plant and climatic
factors on the Cd and Zn content of plants is addressed.
Sewage sludges generally contain Cd and Zn at concentrations which exceed
those found in most soils, and their addition thus increases the total concen-
tration of Cd and Zn in soils. The concentrations of Cd and Zn in sewage sludges
depend upon the characteristics of the sewage influent and the treatment pro-
cesses employed.
The availability of sludge-borne Cd ,and Zn to plants after application of
sludge to soils appears to depend upon the chemical forms present and other
characteristics of the sludge as well as the soil. A variety of inorganic and
organic forms of Cd and Zn of low solubility may coexist in sludges. A hypoth-
esized mechanism for retention of Cd and Zn in sludge solids is coprecipitation
of these metals with iron, aluminum and manganese oxides, hydroxides, carbonates
and phosphates. Further research is needed to elucidate the chemical species of
Cd and Zn in sludges. This information is expected to improve estimations of
solubility and relative availability to plants of Cd and Zn after application
of sludges to soils.
. Plant species differ markedly in their ability to accumulate Cd and Zn from
soils. In general, under similar soil conditions, Cd and Zn concentrations are
greater in leafy vegetables and the vegetative parts of crops than in fruit,
grain or tubers. The content of Cd depends also upon the cultivar grown; the
Cd content of corn grain and leaves may vary tenfold among cultivars. Environ-
mental factors, including temperature and soil moisture, also may modify the
concentration of Cd and Zn in crops. Frequently the concentrations of Cd and
Zn in plant tissues increase when plants are grown under suboptimal (stress)
conditions.
The primary soil factors controlling the uptake by plants of Cd and Zn added
to .soils in sewage sludge are the amounts of these metals present as a result of
the treatment, and the pH of the treated soil. At any given level of Cd or Zn,
the concentration of the metal in plant tissue decreases with increasing soil pH.
The impact of sludge-borne Cd and Zn on plants is least in calcareous soils.
Experiments to evaluate the effect of soil cation exchange capacity (CEC)
on uptake of Cd and Zn have yielded conflicting results. In greenhouse studies,
increasing the soil CEC by adding organic matter or bentonite altered the soil
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pH, and the effects of CEC and pH could not be separated. Similarly, in studies
involving untreated soils differingj in CEC, the soils have differed in pH and
other properties as well, and these;differences have prevented identifying un-
ambiguously an effect of CEC. The CEC of a soil cannot be modified without
altering other soil properties. However, the pH buffering capacity of soils
increases with the CEC; hence, the potential for increased Cd and Zn uptake by
plants associated with acidification of soil following sludge application is
less in soils with high CEC than in those with low CEC. CEC is viewed more ap-
propriately as a general, but imperfect, indicator of the content of soil compo-
nents that limit the solubility of Cd and Zn than as a specific factor in the
availability of these metals.
The uptake of Cd and Zn by plants increases with the total concentration
of these metals in soils. In calcareous soils, however, the amounts of Cd and
Zn added have only a relatively small effect on the content of these elements
in plants because the metals have relatively low solubility in the presence of
calcium carbonate.
In agricultural operations, sewage sludges are generally applied annually
over a number of years. Although the concentrations of Cd and Zn which occur
in crops in the first year following sludge application can be expressed as a
function of the amounts of Cd and Zn applied, these data cannot necessarily be
extrapolated to estimate the effect ;of the same total amount applied in small
increments over a number of years. To accomplish this, data are needed on the
changes in the chemical properties of sludge-treated soils with time and on the
influence of these changes on the availability of Cd and Zn. The effect of time
superimposed on changes in the chemical properties of soils receiving repeated
additions of sludge has not been adequately investigated. The experimental data
available permit only a qualitative or possibly semiquantitative assessment of
the effects of single and repeated additions of sludge on the content of Cd
and Zn in plants.
Most of the available data were obtained from field"experiments in which
repeated applications of sewage sludge were made over a period of years. With
calcareous soils, only small increases in Cd and Zn concentrations in plants
have occurred with either single or repeated applications. With noncal-
careous soils, the concentrations of Cd and Zn in the crops in most: experi-
ments have increased with the amounts of Cd and Zn applied following the first
sludge application. After repeated annual sludge applications, the concentrations
of Cd and Zn in crops have been found to be either approximately equal to or less
than those expected on the basis of the effects of applying the same total amount
of the metals in a single year.
Some data indicate that the availability to plants of Cd and Zn added to
soils decreased with time after termination of repeated sludge applications.
In one instance reviewed, the Cd content of corn grain was no greater in the
third year following termination of |sludge applications than it was in the
control soil, although the Cd content of the corn leaves was still greater
on the sludge-treated soil than on the control.
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Other data indicate that there was no clear decrease in availability to
plants with time. In one instance reviewed, the increases in Cd concentrations
in both the leaves and grain of sweet corn for the first 4 years following termi-
nation of annual sludge applications appeared to be in the same range as those
observed during the applications.
Management of soil pH is the most critical factor in evaluating the impacts
of single and repeated additions of sludge on uptake of Cd and Zn by plants.
For plants which tend to accumulate Cd (e.g., leafy vegetables), a decrease in
soil pH from 6 to 5 will likely result in greater increases in Cd and Zn con-
tent than either (1) doubling the amount of Cd or Zn in single or repeated
applications to a soil at pH 6.5 or (2) allowing the soil pH to decrease from
7 to 6.
In view of the effects of single and repeated additions of sludge-derived
Cd and Zn on the content of these metals in plants, the residual effects after
sludge applications have ceased, and the effects of soil pH on the availability
of these metals to plants, it seems evident that considerable increases in con-
centration of Cd and Zn in many crops cannot be avoided when sludges high in
these metals are applied unless the total amounts of the metals supplied in
single and repeated additions are limited and unless the soil reaction is main-
tained near or above neutrality. Even at a soil pH of 6.5, the Cd added in many
sludges is sufficient to increase the Cd concentration in most crops.
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INTRODUCTION
Cadmium (Cd) and zinc (Zn) are naturally occurring trace metals that are
ubiquitous in soils. Zn has been established as an essential element for plant
and animal life. Although essentiality has not been demonstrated conclusively
for Cd, it has been shown in one study to improve the growth of rats at low con-
centrations (Schwarz and Spallholzi, 1978). Native concentrations of these metals
in soils vary considerably depending upon the geological origin and weathering
of the soil materials. The concentrations of Cd and Zn in soil can be increased
by atmospheric depositions, addition of Zn and phosphate fertilizers, and addi-
tion of plant residues and wastes including sewage sludge.
The Cd and Zn content of plants reflects the total Cd and Zn content of
the soil as well as a number of interacting sludge, soil, plant and climatic
factors. Under certain conditions, Cd and Zn may accumulate in crops to levels
which may reduce crop yields. Elevated levels' of Cd in food crops due to appli-
cations of sewage sludge or other causes are of concern as a potential hazard
to human health.
Increased emphasis is being placed on applying municipal sewage sludges
to agricultural land because of constraints on alternative disposal methods,
such as the ban on dumping sludge in the ocean and air pollution problems and
fuel requirements associated with sludge incineration. Although sewage sludges
can be applied to drastically disturbed lands and to lands used in silviculture
and ornamental horticulture, the primary focus of this report is the applica-
tion of sewage sludge to agricultural land used for growing crops which enter
human or animal diets.
Two basic approaches are considered when developing the appropriate sludge
application rate for agricultural soils: (1) using the sludge as a fertilizer
for its content of plant nutrients and (2) using the sludge on sites dedicated
to sludge application on which the rates of application may or may not be based
upon the plant nutrient content. When used as a source of plant nutrients,
usually nitrogen or phosphorus, the amount of sludge applied per year can be
based on (1) an annual Cd limitation, e.g., 2 kilograms per hectare (kg/ha)
per year, (2) the amount of nitrogen or phosphorus required by the crop grown
or (3) a combination of both criteria. The third approach is typically used
for privately owned agricultural land on which food or feed crops are grown
and on which the farmer uses a conventional soil testing program to monitor
the soil after sludge application. The rationale for limiting sludge addi-
tions on the basis of the nitrogen required by the crop is that nitrate
leaching and subsequent contamination of- ground water will be no greater
than that caused by use of commercial fertilizers.
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The concern over Cd entering the human diet prompted the Environmental
Protection Agency (1979) (EPA) to establish limits on both the annual and
cumulative amounts of Cd that may be added to soils in the form of sewage
sludge. The criteria limit annual Cd loadings from sludge additions to soil,
but do not directly limit the amount of nitrogen applied. In addition, the
criteria stipulate the following for all soils receiving solid wastes which
are currently used or may in the future be used to grow crops for the food
chain: (1) the pH of the mixture of soil and solid waste is to be 6.5 or
greater at the time of each solid waste application (no pH limitation is
imposed if on a dry-weight basis the waste contains Cd at a concentration of
2 milligrams per kilogram (mg/kg) or less); (2) a maximum annual application
of 0.5 kg of Cd/ha for soils growing tobacco, leafy vegetables or root crops;
and (3) a maximum annual Cd application for other crops of 2 kg/ha from the
present to 6/30/84, 1.25 kg/ha from 7/1/84 to 12/31/86 and 0.5 kg/ha after
1/1/87.
The number of years that soils can receive sewage sludge is based on
the cumulative amounts of Cd applied.1 , The EPA criteria established cumulative
Cd limits of 5 kg of Cd/ha for soils having a "background pH" of <6.5. For
soils with a background pH >6.5 or for soils that will be maintained at pH
6.5 or above whenever crops entering the human food chain are grown, the
cumulative amount of Cd allowed increases with increasing soil cation ex-
change capacity (CEC) as follows: <5 milliequivalents per 100 grams (meq/
100 g), 5 kg of Cd/ha; 5 to 15 meq/100 g, 10 kg of Cd/ha; and >15 meq/100 g, 20
kg of Cd/ha.
When sewage sludge is applied to agricultural land dedicated to sludge
application, the quantities of Cd applied may exceed those described in the
preceding paragraph, and this results in the need to monitor the sludge appli-
cation site to preclude nitrate movement into surface and ground water. The
EPA criteria specify that all crops grown on such sites, including pasture
crops, forages and grains, must be used for animal feed and that the soil pH
must be maintained at 6.5 or above. Crop residues and animal wastes must be
returned to the sludge application site.
Although Cd-Zn interactions may influence the absorption of Cd from soils
by plants (Walsh et_ al^., 1976) and from the diet by animals or humans (Fox et
al., 1979), the principal reason for discussing both Cd and Zn in plants grown
on soils treated with sewage sludges is that Zn contents of plants may be useful
as a model for Cd behavior in many soil-plant.systems in which Cd data do not
yield a discernible trend due to experimental or analytical limitations. Cd and
Zn have some similar chemical and biochemical properties.
An alternative approach was suggested by a North Central Regional Research
Committee which recommended that total sludge loadings be limited by cumula-
tive additions of lead, zinc, copper, nickel and cadmium (NC-235, 1976).
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Some of the research data presented in this report are from experimental
plots on which sludge has been applied in quantities 50 to 100 times greater
than those recommended on the basis of the nutrient requirements of the crop
grown. The data from such plots, however, are valuable in evaluating the
effect of sludge application on the concentration of Cd and Zn in various
plant tissues.
Current guidelines on sludge application rates are based on an assortment
of data from greenhouse and field studies in which soils were treated with
sludges, sludges supplemented with metal salts or metal salts alone. Plant
data derived from studies involving addition of metal salts to soils should
be viewed with caution as an indicator of the effects of adding comparable
rates of Cd to soils in the form of sludges. Concentrations of Cd and Zn
in. plants grown on sludge-treated soils are usually much higher when the
plants are grown in the'greenhouse than in the field (DeVries and Tiller,
1978), and their use is questionable in quantitative predictions of metal
concentrations in the human diet. Consequently, this report will make use
of field data whenever possible. ;
This report summarizes available data on the relative effects on crop
composition of single and repeated i additions of Cd and Zn to soils in the
form of sewage sludge, as influenced! by sludge properties, crop species and
cultivar, soil properties, and climatic factors. The experimental findings
are not always as definitive as might be desired because of limitations in
experimental design, experimental error, variations in soil pH values, sea-
sonal differences in growing conditions that may affect the results, and
differences among sludges, soils and! other factors that are not understood.
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SEWAGE SLUDGE CHARACTERISTICS
Wastewaters are derived from a variety of domestic and industrial sources
and have a wide range of Cd and Zn contents (Table I)2. In general, industrial
sources tend to contribute greater amounts of Cd and Zn to wastewaters than
do domestic sources (Gurnham et al., 1979).
Industrial sources of Cd in wastewaters include metallurgical alloying,
ceramics manufacturing, electroplating, inorganic pigments, textile printing,
and chemical industries (Patterson, 1975). Of the total industrial Cd use,
90% is utilized in electroplating, pigments, plastic stabilizers, alloying
and battery manufacturing (Page and Bingham, 1973). Most of the remaining
10% is used for television tube phosphors, fungicides, rubber curing agents
and nuclear reactor shields and rods.
Industries which discharge Zn in their wastewater include steel works
with galvanizing units, Zn and brass metal works, Zn and brass plating works,
silver and stainless steel tableware manufacturing, viscose rayon yarn and
fiber production, ground wood pulp production, news print paper production,
and pigment manufacturing. The primary source of Zn in wastewaters from
plating and metal processing industries is the solution adhering to the metal
product after removal from pickling or plating baths. Wastewaters with little,
if any, industrial contribution can still contain appreciable Zn concentrations,
probably because of the wide use of galvanized pipes in residential water supply
and wastewater transport systems.
Several different wastewater treatment processes have been developed and
are used in the United States. They include primary treatment, which removes
only suspended solid materials; secondary treatment, which removes additional
suspended solids; and tertiary treatment, which involves addition of coagulants
to remove certain dissolved solids. The residue remaining after wastewater
treatment is referred to as sewage sludge and must be removed from the treat-
ment plant. The Cd and Zn in wastewaters tend to accumulate in the sewage
sludge (Table 1).
Cadmium And Zinc In Sewage Sludge
The chemical composition of sewage sludges has been evaluated in numerous
localities including Wales and England (Berrow and Webber, 1972), Sweden (Berggren
and Oden, 1972), Michigan (Blakeslee, 1973), eight states in the north central
and eastern regions of the United States (Sommers, 1977), Iowa (Tabatabai and
2 Tables and figures are found on page 39 et seq.
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Frankenberger, 1979), Indiana (Sommers ^t al., 1972), Pennsylvania (Doty _et al.,
1977), and Wisconsin (Konrad and Kleinert, 1974). A common finding of these
surveys was the high degree of variability in the chemical composition of
sludges. This finding is illustrated for Cd and Zn by Table 2. The compo-
sition of sewage sludges varies also with time at a given treatment plant
(Doty at al., 1977; Sommers et al., 1976).
The concentrations of Cd and Zn in municipal sewage sludges exceed those
in the wastewater because of bioaccumulation, adsorption and coprecipitation.
Other important factors, however, influence the Cd and Zn concentrations in
sludges.
The distribution of metals through municipal sewage treatment plants is
predictable in a quantitative mannet (Patterson, 1975, 1979). Each influent
metal is distributed between the sewage soluble phase and the suspended par-
ticulate material. The relative distribution of Cd and Zn between the soluble
and particulate phases is extremely variable, and is believed to be a function.
of total concentration, concentration of other chemical constituents, and other
sewage characteristics (e.g., pH, organic carbon, cyanide, etc.). The principal
points of sludge generation in sewage treatment are primary sedimentation, in-
cluding Imhoff sedimentation of raw! sewage, and secondary sedimentation of
waste (excess) biological activated sludge mass or of chemically treated
primary effluent. Chemical treatment processes such as additions of calcium
hydroxide or salts of iron or aluminum increase sludge production substantially
(Metcalf and Eddy, 1974). During both primary sedimentation and secondary
treatment, soluble metals are removed from solution through sorption by sus-
pended solids and uptake by the microorganisms therein.
Table 1 shows some performance features relating to Cd and Zn concentration
for three activated sludge sewage treatment plants of the Metropolitan Sanitary
District of Greater Chicago. Thesel plants vary in size and in the character-
istics of their raw sewage, and theV cover a wide range of sources of Cd and Zn,
ranging from primarily domestic to jieavy industrial input (Lue-Hing, 1979). It
seems clear from these data that me|tal concentrations in raw sewage directly
influence the sludge metal concentrations. However, the values for the sludge
concentration factor show that the [degree to which metals are concentrated
in the sludges differs among plants, being five times greater for Zn at the
Hanover Park plant than at the West-Southwest plant. On the other hand, the
Zn content of the West-Southwest sludge is four times greater than that of the
Hanover Park sludge.
Sludge treatment processes used following primary and/or secondary sedi-
mentation and prior to application to land may include concentration by gravity
or centrifugation; stabilization by| chemical addition (e.g., calcium hydroxide) ,
digestion or composting; dewateringi by mechanical means; and drying by heat
treatment or solar drying beds.
There seems to be little direct .scientific evidence which relates sludge
processing schemes to Cd and Zn availability to plants following sludge appli-
cation to agricultural soils. However, there is evidence indicating that the
combination of sludge type and processing may influence the retention of sludge-
derived Cd and Zn by soils.
8
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Stover et_.ajL. (1976) used a sequential extraction procedure to fractionate
the metals in a range of sludges. Their findings indicated that organically
bound Zn is the predominant form of this metal and that zinc carbonate may also
be present in significant quantities in some sludges. For Cd, the predominant
form appears to be cadmium carbonate with lesser amounts of organic and sulfide
forms. According to Sommers (1977), available data suggest that several forms
of Cd and Zn are present in sludges and that different forms may predominate in
different sludges. Moreover, changes in chemical forms probably occur after
sludges are incorporated into soils, with resulting changes in Cd and Zn avail-
ability to plants.
Theoretical Mechanisms For Retention Of Cadmium And Zinc In Sludges
The availability of Cd and Zn to plants is consistently lower when the
metals are applied to soils in the form of sewage sludge than when they are
applied in the form of inorganic salts. For example, greenhouse experiments
by Dijkshoorn and Lampe (1975) showed Cd concentrations in plants to be about
twice as great when Cd was added to soil in the form of cadmium sulfate as when
an equal amount was added in sludge. Some studies have shown large differences
in Cd availability for sludges with similar Cd contents, but the reasons are not
known.
One theory that seems to be in accord with most of the available data on
relative availability of Cd in different sludges to plants is that the Cd is
coprecipitated as a trace constituent in the inorganic precipitates in the
sludge; These precipitates are generally hydrous oxides of iron and aluminum;
phosphates of iron, aluminum and calcium; ferrous sulfide; and/or calcium car-
bonate. The relative amounts of these major components, as well as the amounts
of Cd and Zn present in the sludges, depend on waste sources and treatment pro-
cesses, and particularly on the use of iron, aluminum or calcium compounds for
phosphate removal or sludge conditioning.
According to solid-solution theory (Stumm and Morgan, 1970), when, a com-
patible trace cationic constituent is incorporated into a crystal, the concen-
tration of the trace cation at a particular point in the crystal depends on
the relative activities of the two cations in solution at the time precipi-
tation was occurring at that point and on a distribution function. If the
trace cation is not compatible, it cannot be incorporated into the crystal
because of differences in size, charge or bond type. However, the cation
may be adsorbed onto the surface of the growing crystal and subsequently
occluded as the crystal grows around it. In either case, the cations inside
the crystal are not exchangeable with ions in the soil solution and, while in
that form, do not contribute to the availability of the cation to plants.
Cd and Zn have been shown 66 be adsorbed on surfaces of hydrous oxides
of iron and aluminum (Kinniburgh £t a!L., 1976, 1977), and they would probably
coprecipitate with these compounds under the conditions existing in a sewage
treatment plant. Coprecipitation with phosphates, carbonates and sulfides
would also be expected, as most of the heavy metals form precipitates of low
solubility with these anions.
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If a coprecipitation mechanism is responsible for immobilization of much
of the Cd and Zn in sludge, only the labile, adsorbed metal ions on the surface
of the precipitates and in the organic adsorption sites will be in equilibrium
with the solution phase. The quantities of these labile metal ions may be
estimated experimentally by the method of isotopic exchange. If an adsorbed
phase controls metal solubility in soils, the concentration of the metal in
solution will be governed by the adsorbed phase. Following addition of sludge
to soil, adsorption sites on the soil will tend to lower the Cd concentration
in solution. When large amounts of sludge are applied, the Cd adsorption capac-
ity of the sludge may dominate the system, and the soil may have little effect
on the Cd solubility.
Support for this theory in studies of sludge is found in the results of
experiments by Cunningham et al. (1975a). In comparing Cd uptake from two
noncalcareous sludges in the greenhouse, they found that the average concen-
tration of Cd in plant tissue was about the same for the two sludges (1.5 vs.
1.4 mg/kg) even though the Cd content of the sludges differed by a factor of
3 (76 vs. 220 mg/kg). The sludge with the lower Cd content had a lower iron
content (1.2 vs. 7.9%) and also a lower phosphorus content (2.9 vs., 6.1%).
Thus, the low Cd availability occurred in the sludge with a relatively high
content of substances with which Cd could coprecipitate.
Additional support is found in unpublished work conducted in Wisconsin
(Keeney £t a!L., 1980). In a field study, the Cd concentration in corn leaves
from plots treated with a sludge containing 229 mg of Cd/kg, 3.0% iron, 1.1%
aluminum, 4.7% calcium and 1.6% phosphorus was nearly three times as high
(1.7 vs. 0.6 mg/kg) as in corn leaves from plots treated with the same amount
of Cd supplied by a sludge containing 180 mg of Cd/kg, 7.8% iron, 2.5% alumi-
num, 1.5% calcium and 3.0% phosphorus. The isotopically exchangeable or labile
Cd was also found to be three times [higher for the sludge low in iron and
phosphorus even though the total Cd [concentrations in the two sludges were
similar.
The unpublished work at Wisconsin also included a greenhouse study in
which Cd concentrations in corn tissue were compared using sludge additions
with similar Cd applications (1.6 vs. 1.8 kg/ha) from sludges with approxi-
mately the same concentrations of iron (7.8 vs. 7.2%), aluminum (2..5 vs.
4.7%), calcium (1.5 vs. 1.5%) and phosphorus (3.0 vs. 3.5%), but differing
in total Cd concentration (180 vs. 9 mg/kg). The sludge containing the
higher content of Cd increased the C^d concentration from 0.6 mg/kg in the
control plants to 1.2 mg/kg. The Cd content of the corn tissue from the soil
treated with low-Cd sludge was not different from the control. The low-Cd
sludge apparently supported a lower level of available Cd even though the
total amounts of Cd added were the same. However, the total additions of
iron and organic matter were about 20 times as great for the low-Cd sludge
as for the high-Cd sludge, so that the total Cd adsorption capacity of the
added sludge was much higher for the low-Cd sludge.
In another greenhouse study, Bates et al. (1979) added a number of
sludges to soils cropped to annual ryegrass over a period of about 5 years.
A total of 14 crops of ryegrass was grown, with the sludge being added prior
10
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to seeding each crop. The cumulative Cd loadings were 10.6 kg/ha for the
Sarnia sludge and 12.1 kg/ha for the Guelph sludge. The sludges had similar
ratios of phosphorus to Cd at the start of the 14th crop, but the ratios of
iron to Cd were 889 to 195 for the Sarnia and Guelph sludges, respectively.
The average Cd concentrations in the 14th crop of ryegrass were 1.35 mg/kg
for the Sarnia sludge and 2.35 mg/kg for the Guelph sludge. Again, with
nearly equal additions of total Cd, the lower Cd availability was associated
with the sludge having the higher iron content.
For the seemingly few sludges in which much of the Cd is not isotopically
exchangeable and does not contribute directly to the supply of Cd available
for plants, marked differences in the trend of Cd availability with time could
occur when different sludges are applied to different soils. If Cd were co-
precipitated with calcium carbonate or calcium phosphate in the sludge and if
the sludge were applied to an acid soil, the precipitates would dissolve over
a period of time, and the coprecipitated Cd would be released. On the other
hand, if the same sludge were applied to a calcareous soil, the coprecipitated
Cd would probably remain immobilized. Cunningham et^ al_. (1975a) found an
average of 10.5 mg of Cd/kg in leaf tissue when plants were grown in a soil
at pH 6.8 which had been treated with a calcareous sludge containing 460 mg
of Cd/kg and 18%--calcium-; Oaiy 1.4 mg of Cd/kg was found in plant tissue from
the same soil to which similar quantities of a noncalcareous sludge with a
higher content of iron and phosphorus and 220 mg of Cd/kg had been applied.
In this case, it would appear that either the calcium precipitates were less
effective than the iron phosphate precipitates in immobilizing the Cd or Cd
was released due to dissolution of some of the calcium compounds (e.g., calcium
carbonate) in the slightly acid soil.
The Cd in noncalcareous sludges that is not associated with organic matter
would likely be coprecipitated primarily with hydrous oxides or phosphates of
iron and aluminum. These forms would not be expected to be altered rapidly by
interaction with either acid or alkaline soils. However, the solubility of the
isotopically exchangeable or labile Cd fraction would be affected by the soil
pH. If the Cd were coprecipitated with ferrous sulfide, some Cd would probably
be released to a more labile form on oxidation of the sulfide.
11
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CROP RESPONSE TO CADMIUM AND
ZINC ADDITIONS IN SLUDGE
Crop response to Cd and Zn varies( with crop species. Various classes of
vegetation exhibit differential uptake patterns, which have been well documented
in the literature and in a previous CAST report by Walsh et al. (1976). Im-
portant crops including small grains,> vegetables, legumes and forage crops
show different tolerances or sensitivities to substrate Cd and Zn concentra-
tions. Crop varieties and parts of individual plants may vary considerably in
content of Cd and Zn. Vegetative parjts generally contain higher concentrations
of Cd and Zn than does the fruit. Moreover, Cd and Zn uptake by plants may
vary from season to season due to differences in factors such as moisture,
temperature and disease. Evidence continues to appear in the literature that
uptake of Cd and Zn by plants from sludge-treated soils increases with in-
creased rate of application of a given sludge, increased Cd and Zn content
of the sludge at a constant application rate, and decreased soil pH at a
constant metal loading.
Differential Uptake Of Cadmium And Zinc By Crop Species
In recent years, a large number of plant species have been screened with
respect to Cd accumulation. Leafy vegetables are generally the greatest accumu-
lators, whereas the edible portions of squash, tomato and radish tend to have
low Cd levels (Dowdy jat al_., 1975; Giordano ej: ad., 1979b) . Giordano et al.
(1979b) found that cabbage absorbs less Cd than other leafy vegetables and
is an apparent excluder of Cd compared with lettuce (Table 3). Cadmium con-
centrations observed in lettuce, chard, radish and carrot increased with the
quantity of sludge applied to a calcareous Domino soil (Chang £t £JL., 1979)
(Table 4). Concentrations of Cd in radish tubers were approximately half of
those in the tops. In contrast, only 15% as much Cd appeared in potato tubers
as in the tops (Giordano ^t^ al^., 1979!b) . Cd uptake by sorghum, soybean, potatoes
and wheat increased with increasing Cd applied to the soil (Baker el: al., 1979as
1979b) (Table 5). The Cd concentration in potato tubers was approximately one-
tenth that found in the leaves.
Analysis of the leaves of corn, cotton and soybeans grown on sludge-treated
soils showed concentrations of Cd to be <1 mg/kg in all cases except: in one cul-
tivar of corn which contained 1.4 mg/kg with the .greater application of sludge
(Table 6). Concentrations of Cd were considerably higher in soybean grain than
in corn grain and were usually higher in soybean grain than in cotton seed al-
though levels were <1 mg/kg (Table 7).. Concentrations of Zn were higher in both
leaf and grain of soybeans than in the other crops, as has been found for other
elements (e.g., calcium and magnesium) (Tables 6 and 7).
12
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Tobacco grown on soils (pH 5.6 to 6.3) treated with various sources and
quantities of sewage sludge (0.8 to 4 kg of Cd/ha) showed Cd concentrations
ranging from 14 to 33 mg/kg in leaves from the upper portion of the plant,
and 20 to 55 mg/kg. in lower leaves. According to these unpublished findings
by R. L. Chaney, tobacco must be considered as much of an accumulator of Cd
as leafy vegetables, at least when grown on acid soil.
Additional data on relative concentrations of Cd or Zn in various crop
species are available. For both Cd and Zn, concentrations are greater in
Swiss chard and lettuce than in soybeans or oat grain (Tables 15 and 16).
A study involving Cd applications of 14 to 203 kg/ha indicated that the
increases in Cd content of the grain from application of sludge were
greatest with oats, less with soybeans and least with corn (Tables,27 and
28). Mahler et al. (1978) and Bingham (1979) have identified several
plant species which are sensitive to Cd toxicity (spinach, lettuce, curly
cress and soybean) and some that are relatively tolerant (tomato, squash,
cabbage and paddy rice). Toxicity to plants is more acute and occurs at
lesser total concentrations of Gd in acid than in calcareous soils.
Differential Uptake Of Cadmium And Zinc By Crop Cultivars
Cultivar differences in uptake of trace metals have long been recognized.
Millikan (1961) concluded that differences in efficiency of nutrient absorption
and utilization by plants are often greater among cultivars of the same species
than among related species or genera. Similarly, evidence exists for genetic
control of translocation of elements within plants (Epstein and Jefferies,
1964). More recently, evidence has been presented for genetic control of
Cd and Zn uptake and translocation, and attempts have been made by plant
breeders to select for low accumulation of these metals (Hinesly et al.,
1980).
The differential response of soybean cultivars to soil Cd was recently
evaluated by Boggess £t al. (1978) in a greenhouse study. Cultivars grown
on a sludge-treated soil showed variable uptake of Cd (Table 8). The
maximum plant shoot Cd concentration was 6.0 mg/kg, and the minimum was
1.4 mg/kg.
Cultivar differences in Cd and Zn uptake by lettuce were reported by
Giordano et al. (1979b) (Table 8). The two lowest accumulators of Zn were
also the two lowest accumulators of Cd. Chaney and Feder (1980) reported a
Cd uptake of 8.1 mg/kg for the Summer Bibb cultivar of lettuce and an uptake
of 3.8 mg/kg for the Valmaine cultivar.
Data obtained by Hinesly et al. (1978) showed that inbred lines of corn
grown on .a sludge-treated soil differed in accumulation of Cd and Zn in leaves
and grain, again suggesting that the capacity to accumulate Cd and Zn may be
under genetic control. The different lines varied in uptake and translocation
of Cd and Zn (Table 8), with accumulation of Zn not necessarily correlated
with Cd. Similarly, Cd and Zn concentrations in the leaves were not always
correlated with concentrations in the grain. Zn concentrations varied from
62 to 282 mg/kg in the leaves and from 34 to 70 mg/kg in the grain. Cd con-
centrations varied from 2 to 63 mg/kg in the leaves and from 0.1 to 3.9 mg/kg
13
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in the grain. These data suggest that the mechanisms controlling uptake and
translocation of Cd and Zn are independent of each other. In the same study,
Cd and Zn analyses of the plants grown with different applications of sludge
suggest that variations of Cd and Zn in corn leaves and grain are determined
as much by heritable differences as by differences in plant-available Cd and
Zn in the soil (Table 9).
Overall, the available data suggest that Cd and Zn uptake and translocation
can be genetically controlled and that cultivars can be selected for their low
uptake of these metals and for limiting their translocation to edible parts.
i
Environmental Influences On The Cadmium And Zinc Content Of Crops
The existence of seasonal differences in concentrations of Cd and Zn in
crops is well known. Except for several soil temperature studies,, however, the
environmental influences that may be responsible for these differences do not
seem to have been investigated. In general, concentrations of Cd and Zn in
plant tissue appear to increase with increasing temperatures. Occasionally,
however, plant tissue concentrations are unaffected. Sheaffer et al. (1979)
reported increased Zn concentration in ear leaves, grain and stover of corn as
soil temperature increased from 16° to 35°C (Table 10). The Cd content in corn
seedlings increased significantly while only slight elevations in Cd content of
the ear leaf and grain occurred with increasing soil temperature. In corn
stover, the Cd concentration decreased with increasing temperature. In
contrast, the concentration of Cd in soybean shoots increased with increasing1
temperature and was further elevated by small (25 mg/kg of soil) applications
of Zn. Large applications of Zn (400 mg/kg of soil) depressed the Cd concen-
trations in shoots below those in plants grown on soil which received no Zn
(Haghiri, 1974).
Heating sludge-treated soil ati or above 27°C to simulate the effect of a
different season did not increase the Cd or Zn concentration in edible parts
of lettuce, eggplant, tomato, potato, corn, squash or bean (Giordano et al.,
1979b). Heating the soil appeared to increase the levels of Zn in broccoli.
As the temperature of the soil increased, Cd concentrations in pepper increased
in one year, but were unaffected two years later. Heating increased the con-
centrations of Zn in foliage of tomato, potato and corn, and increased the con-
centrations of Cd in eggplant, potato, corn and squash.
Chang et al. (1979) observed seasonal effects on the relationship between
Cd in crops and available Cd in the soil during a 3-year field study. The
behavior pattern varied with the crop; some crops had higher Cd concentrations
in the fall than in the spring (e.g., radish leaves and tubers) , while others
exhibited higher Cd concentrations'in the spring than in the fall (e^g., Swiss
chard). The results were probably^affected by the timing of the sludge appli-
cations, which were made twice a year over the 3-year period.
The effect of season on the absorption of Cd and Zn by crops is likely
to be inconsistent in view of the many factors (e.g., moisture, temperature,
aeration and disease) that can vary and interact substantially from season to
season to modify Cd and Zn uptake. Representative seasonal effects on Cd and
Zn concentrations in corn, lettuce land pepper are shown in Table 11. Where
14
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trends do occur with time, fixation and solubilization reactions that affect
the solubility of Cd and Zn in the soil are likely to have a greater influence
on the concentrations of these elements in plants than are seasonal effects.
In summary, Cd and Zn uptake and accumulation by crops are affected by plant
species and cultivar, soil and other environmental factors. Often, Cd concen-
trations in plant tissues are low (<1 mg/kg), and changes in concentration may
not be attributable to a specific factor. In general, the levels of Cd and Zn
found in plant tissues increase with increasing metal loading rates irrespective
of whether the metal is applied as an inorganic metal salt or as sewage sludge.
Seasonal variation may affect the levels of Cd and Zn in plants. Higher
accumulations usually occur at higher soil temperatures. Moisture stress,
often occurring with high summer temperatures, can also lead to higher con-
centrations. With increased plant stress, less biomass is produced, and the
resulting Cd and Zn concentrations in the plant are higher than when the plant
is growing under optimum conditions. Plant species vary in the amounts of Cd
they accumulate. Leafy vegetables usually show greater concentrations of Cd
than do most other crops. Cultivars also have been shown to absorb different
amounts of Cd and Zn. The vegetative parts of plants contain more Cd than do
the grain, fruit or tubers.
15
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EFFECT OF SOIL PROPERTIES ON THE
RESPONSE OF CROPS TO CADMIUM
AND ZINC ADDITIONS
Soil chemical properties may affect the partitioning of Cd and Zn between
the soil solution and the solid phase and thus influence their absorption by
plants. Several investigators have suggested that adsorption is the predomi-
nant mechanism of trace metal removal from dilute solutions by clay minerals,
metal oxides and organic matter, and by whole soils (Farrah and Pickering,
1977; James and MacNaughton, 1977; Riffaldi and Levi-Minizi, 1975; Street
j2t al_., 1977). As is true for manyjother trace metals, adsorption-desorption
processes involving Cd and Zn show a strong pH-dependence. Since a change in
pH may affect not only the metal species in solution (e.g., hydroxy, carbonate
or phosphate complexes), but also the surface properties of the adsorbate (i.e.»
charge characteristics), a quantitative description of the exact mechanism in-
volved in trace metal adsorption by naturally occurring soil components is not
possible (Davis et al., 1978). In btudies with silicate clay minerals, Farrah
and Pickering (1977) found that increasing the pH from 4.5 to 7.5 sharply in-
creased Cd adsorption. In similar studies with iron and aluminum oxides,
Kinniburgh et al. (1977) found that adsorption of Cd and Zn was strongly
pH-dependent and occurred at a pH less than the zero point of charge for
the oxides (i.e., the surface was, positively charged). Studies with whole
soils have shown a similar pH-dependent nature for both Cd (Singh, 1979) and
Zn (Cavallaro and McBride, 1978) adsorption. In addition to the adsorbed
forms, Cd and Zn may be present in soils in discrete precipitates or copre-
cipitates with iron or aluminum oxides or alkaline earth carbonates (see the
section on sewage sludge characteristics), or bound to soil organic matter
through either exchange or chelation mechanisms. In either case, metal solu-
bility will be a function of pH. One property that reflects the combined con-
tributions of soil clay minerals and organic matter is the cation exchange
capacity. The Environmental Protection Agency (1979) assumed that there is a
relationship between this property and the availability to plants of sludge-
borne Cd. This section summarizes the available data on the effect of soil
metal concentration, soil pH, soil cation exchange capacity and other soil
factors that influence the concentration of Cd and Zn in plants grown on
soils treated with sewage sludge.
Soil Cadmium And Zinc Concentration
The concentrations of Cd and Zn in plants tend to increase with the total
Cd and Zn concentrations in the soil. The Cd and Zn concentrations in soils
16
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cover a wide range because of differences in the Cd and Zn content of soil
parent materials, additions of metal-containing fertilizers and contamination
through industrial activities.
Published data show that the background concentrations of Cd in soils typi-
cally range from a few tenths of a mg/kg to 1 mg/kg. In certain regions of the
United,States native Cd concentrations in soils are atypically high. In Cali-
fornia, certain soils derived from a shale parent material contain unusually
high concentrations of Cd (5 to 20 mg/kg). Although the current data base is
limited, concentrations of Cd in native vegetation collected from soils naturally
high in Cd tend to exceed concentrations in the same plant species in adjacent
locations grown on soils low in natural Cd (Olson j2_t a^., 1978; Cannon, 1955)
(Table 12). The availability of Cd to Swiss chard from soils naturally high
in Cd has been evaluated in greenhouse studies (Lund and Page, 1980). Data
obtained from these studies show that, as the concentration of Cd in the soil
increases, the concentration in Swiss chard leaves increases also (Table 13).
Chang and Page (1979) also observed greater concentrations of Cd in Swiss chard
leaves from plants grown on a soil naturally high in Cd (>5 mg/kg) than were
normally observed for Swiss chard leaves from plants grown on typical agricul-
tural soils. In summary, the information reviewed indicates that the avail-
ability of Cd to plants from natural sources of Cd in soils tends to increase
with the total quantity present in the soil.
Phosphorus fertilizers frequently contain greater concentrations of Cd
than are typically found in soils, and published reports show increased concen-
trations of Cd in surface soils following long-term repeated applications of
such fertilizers (Williams and David, 1973; Mulla _e_t aJL., 1980). Studies by
Williams and David (1973, 1976), for example, show that long-term applications
of Australian superphosphates (20 or more years) containing concentrations of
Cd less than 50 mg/kg resulted in concentrations of 0.212 mg of Cd/kg in topsoil
versus 0.046 mg of Cd/kg in similar soils receiving no phosphorus fertilizer.
In a greenhouse study, concentrations of Cd in oats, subterranean clover and
alfalfa grown on soils treated with phosphorus fertilizers were consistently
greater than those of similar crops grown on nontreated soils. Reuss et al.
(1978) observed that the concentrations of Cd in peas, radish and lettuce were
increased by, and linearly related to, the Cd concentration of the P fertilizer
applied to the soil. Mulla et al. (1980) determined concentrations of Cd and
phosphorus in soils fertilized with the equivalent of approximately 175 kg of
phosphorus/ha/yr (as treble superphosphate) over a 36-year period. Concentra-
tions of Cd in surface soil (0-15 cm) were highly correlated (r = 0.89) with
the concentrations of total phosphorus,, indicating that the source of Cd in
the soil was .the phosphorus fertilizer.: The concentrations of Cd in surface
soil receiving the phosphorus fertilizer for the 36-year period averaged 1.0 mg
of Cd/kg, and were considerably greater than the concentrations in the controls
(0.07 mg of Cd/kg). Concentrations of Cd in barley (grain and leaves) grown in
the field on the soils subjected to long-term phosphorus fertilization were not
increased above those in barley grown on the control soil. Concentrations of
Cd in Swiss chard grown in the greenhouse on surface soil collected from the
phosphorus-fertilized plots, however, were significantly greater than those
from the control soil (1.6 vs. 0.26 mg of Cd/kg of tissue).
17
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Processing of industrial metals ;is an important source of emission of
trace metals, including Cd and Zn, into the atmosphere. Smelting and sintering
of nonferrous metals result in Cd and Zn contamination of the nearby environ-
ment. The major sources of emission are the ore-smelting furnaces in which metals
enter the flue gas stream as fine particulates or volatiles, are discharged from
the stack, and eventually are deposited onto soils and vegetation. Airborne
dusts and fumes from charging furnace's, transporting metal ores, and sintering
and metal-reducing furnaces are also sources of metals found in and near the
operations. There are numerous published results which show increased concen-
trations of Cd and Zn in soil and vegetation close to and downwind from metal
processing operations (Cartright ^t al., 1976; Severson and Gough, 1976;
Buchauer, 1973; Lagerwerff and Brower, 1974; U.S. Environmental Protection
Agency, 1972; Munshower, 1977). Data derived from the U.S. Environmental
Protection Agency (1972) (Table 14) are representative of the extent of con-
tamination which occurs. The data, obtained adjacent to a lead smelter which
began operations in 1888, show high levels of contamination near the plant site.
The data in this section show that differences in Cd and Zn content of
vegetation are associated with differences in the Cd and Zn content of soils
that result from factors other than addition of sludge. This information,
plus that from the section on crop response to additions of Cd and Zn in
sludge, supports the view that the total Cd and Zn concentrations in soils
are a major factor in controlling the uptake of these metals by plants.
Soil pH
Several studies have evaluated the effect of soil pH on Cd and Zn uptake
by crops grown on sludge-treated soils. Decker et_ aJ_. (1978) (Table 15) studied
Cd and Zn uptake by lettuce, Swiss chard, soybeans and oats at different soil
pH levels. The content of both Cd and Zn in lettuce and Swiss chard decreased
with increased pH on both control and sludge-treated plots. The concentration
of Cd in soybean and oat grain was relatively low and was not strongly influ-
enced by soil pH. The concentrations of Cd and Zn in lettuce and Swiss chard
grown on soil treated with Chicago Nu-Earth sludge in quantities of 20, 50 and
100 metric tons/ha (Decker je_t aL^., 1978) (Table 16) decreased with an increase
in pH. The Cd concentration in soybean grain was relatively low and was not
significantly affected by pH, but there was.some decrease in Zn concentration
with increased pH. The concentration of both Cd and Zn in soybean grain was in-
creased by addition of sludge. In these studies, soil pH was adjusted by lim-
ing to 6.7 to 6.9.
Field plot data (Tables 15 to 19) show that Cd and Zn concentrations in
leafy vegetables and corn leaves tend to decrease with increasing soil pH.
However, a significant reduction in Cd and Zn concentrations in corn grain
may not be observed after liming acid soils to approximately pH 6.5. The
concentration of these metals in corn grain is generally low regardless of
soil pH. A reduction in the Cd and Zn concentration in corn grain may result
from liming only when relatively large amounts of these metals are applied to
soils.
Following the application of sludge to soil, the soil pH is likely to de-
crease due to the acidity generated by microbial oxidation of nitrogen present
18
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in ammonium and organic compounds and oxidation of sulfur present in sulfides
and organic compounds contained in the sludge. The magnitude of the pH decrease
will be a function of the pH buffering capacity of the soil/sludge mixture and
the quantity of sludge applied. The pH buffering capacity of a soil increases
with increasing CEC. A number of multiyear field studies on plant uptake of
metals from sludge-treated soils have been conducted in which the soil pH was
changed through microbial processes or was altered by addition of elemental
sulfur or limestone. As shown in Table 20, the Cd and Zn concentrations in
corn leaves and grain increased with increasing additions of sludge at a soil
pH of 5.2 to 5.5 in the presence and absence of fertilizer. Liming the soils
in 1975 and 1976 decreased the concentrations of Cd and Zn in corn plants in
a number of the comparisons. An Illinois study (Hinesly et^ aJ_., 1979a) evalu-
ated the concurrent changes in soil pH and concentrations of Cd and Zn in corn
leaves following annual applications of sewage sludge. Figure 1 shows that,
with continued sludge applications, the ratio of the concentrations of Cd and
Zn in corn leaves to the increase in concentration of these elements in the'
soil as a result of sludge application decreased as the pH increased due to
liming. When the soil pH decreased, the ratio of plant Cd to added Cd in-
creased to a greater extent than did the corresponding ratio for Zn.
Baxter (1980) found that the application of sludge to a calcareous soil
significantly lowered the soil pH, whereas equivalent loadings of Cd and Zn
salts had only a relatively small effect on pH. Presumably because of the pH
effect, the uptake of Cd and Zn by corn was greater from soil treated with sludge
than from soil treated with the metal salts (Table 21). This effect appeared to
be temporary, as suggested by 'the increase in soil pH and the similar concentra-
tions of Cd and Zn in corn leaves from both sludge- and metal salt-treated soils
after 3 years.
In a study by Chaney et al. (1978)- (Table 19), sulfur was applied to plots
to lower the pH because both the sludge and compost used tended to increase the
soil pH. The concentration of Cd and Zn in lettuce was increased in a number of
treatments when the soil pH was reduced following the addition of sulfur. The
increased Cd levels in lettuce persisted in a few of the treatments in the 1977
crop year even though the soil pH increased somewhat. Similarly, in a study by
Giordano et al. (1980) (Table 38) the concentrations of Cd and Zn in the plants
increased when the soil pH was decreased by sulfur additions. Subsequent addi-
tion of limestone raised the soil pH to about 6, resulting in a decrease in Cd
and Zn concentrations in the plants.
Metal uptake by crops typically decreases with an increase in soil pH, but
the results of several studies suggest that liming acid soils to increase pH does
not result in a marked change of metal uptake by plants. Giordano and Mays.(1980)
found little effect of increased (limed) soil pH on Cd and Zn uptake by two corn
varieties (Tables 6 and 7). The concentration of Cd and Zn in cotton seed or
soybean grain also showed little change when the pH was increased from about
5.0 to 6.6. Keeney ^t al. (1980) found some reduction in Cd concentrations in
corn grain with increased pH (Table 17). The Cd additions in both of these
studies were <5 kg/ha. Other studies (Table 18) have shown that the Zn concen-
tration in corn leaves was decreased more consistently than the Cd concentration
when soil of pH 4.7^ was limed to pH 6.5 (Pepper and Bezdicek, 1980).
19
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A complicating factor in evaluating the effect of sludge addition on soil
pH is the properties of different types of sludges. For example, in work of
Chang et aL. (1979), application of a liquid digested sludge caused the soil
pH to decrease while compost addition did not result in a pH change. To
evaluate the relationship between the Cd and Zn concentrations in the plants
and the Cd and Zn applied in the sludges, it was necessary to take into account
the effect of soil pH. This was done by dividing the soils into two arbitrary
groups, those with pH values <6.5 and; those with pH values >6.5. In each group,
the Cd and Zn contents of the leaves were significantly correlated with the Cd
and Zn in the soil. In agreement with results shown previously, the ratios of
Cd and Zn concentrations in the plants to the increases in concentration of Cd
and Zn in the soil as a result of sludge application were higher at soil pH values
<6.5 than at soil pH values >6.5. ;
The concentration of Cd and Zn in plants generally increases as soils
are acidified. Soil management progr&ms which include the addition of acid-
forming fertilizers decrease soil pH values and result in increased uptake of
Cd and Zn by plants unless sufficient limestone is also added.
Soil Cation Exchange Capacity
The CEC of soil is largely determined by the amount and kind of clay,
organic matter, and iron and aluminum oxides. These soil components have
different cation exchange properties,! and their exchange capacities respond
differently to changes in soil pH. !
Determining the influence of CEC on the uptake of Cd and Zn by plants from
soils treated with sludge presents some problems. Sludge adds Cd and Zn, and
it also changes the CEC and other properties of the soil.
Research workers have, used different techniques to study the influence of
CEC on the uptake of Cd and Zn by plants. Latterell at _al. (1976) adjusted the
CEC of a sludged-treated (0,23.2 and 46.7 metric tons/ha) soil from 18.5 to 5.2
meq/100 g by diluting the soil with sand. The results obtained are shown in
Table 22. In the original article, the authors presented the data as Cd and
Zn uptake (meq/100 g of soil) instead of using concentrations as presented in
Table 22. The authors concluded that for a given sludge application rate,
there was no significant difference ip. Cd or Zn uptake with a change in CEC.
The results presented by Latterell ^t! aJL (1976) were recalculated by Task Force
members to express the Cd or Zn in thfe plant material on a concentration basis.
Recalculation of the data changes thej interpretation of the results to some
extent. The concentration of Cd in the plant material increased with increasing
CEC in the control cultures and in the cultures with sludge added at 23.3,metric
tons/ha, and it decreased with an increase in CEC when sludge was added at 46.7
metric tons/ha. The test plants made| poor growth on the cultures with the lowest
CEC (greatest dilution with sand), and the high Cd concentration in these plants
was primarily responsible for the downward trend of Cd concentration in the plants
with increasing CEC of the culture medium. All changes in Cd concentrations,
however, were relatively minor. A decrease in Zn concentration in the soybean
shoots occurred with increasing CEC with both additions of sludge.
20
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Haghiri (1974) modified the CEC of a Toledo clay soil by first removing
the organic matter with I^C^ and then adding organic matter (muck) at rates of
0, 1, 3.5 and 5% by weight to give CEC values ranging from 17.1 to 30.5 meq/100 g.
The influence of CEC on dry weight and Cd concentration of oat shoots is shown
in Table 23. The author concluded that the Cd concentration in oat shoots de-
creased with increasing CEC from organic matter. However, yield also increased
with increasing CEC, and the lower Cd concentration may be a reflection of dilution
rather than lowered uptake through a Cd-CEC interaction.
Sims and Boswell (1978) added bentonite at rates of 0, 5 and 10% to a sludge-
treated Cecil loam soil to produce a range of CEC values from 7.4 to 20.4 meq/100 g
of soil. The addition of bentonite resulted in a significant decrease in the con-
centrations of Cd and Zn in the leaves and grain of wheat. However, the addition
of bentonite also increased the soil pH, and this may have been partially respon-
sible for the observed decrease in Cd and Zn uptake.
Other research workers have used multiple regression techniques to determine
the influence of CEC on the uptake of Cd and Zn by plants grown on different
soils with varying CEC. Mahler ejt al. (1978, 1980) used this technique to
study the influence of CEC on the uptake of Cd by lettuce, sweet corn, tomato
and Swiss chard grown in the greenhouse. Eight soils with pH values varying
from 4.8 to 7.8 and CEC values varying from 6.5 to 37.9 meq/100 g were used in
these studies,. Their data show that CEC resulted in a significant positive con-
tribution to the multiple regression coefficient. However, CEC was not nearly
as important in determining the amount of Cd accumulated by the different crops
as was total Cd in saturation extracts of the soils or soil pH. Keeney et al.
(1980) included CEC and pH as variables in a study of factors influencing the
uptake of Cd by corn seedlings grown in the greenhouse (Table 24). The authors
used eight mineral-soils with CEC values ranging from 3 to 41 meq/100 g for the
correlation analysis. Two organic soils with very high CEC values were also in-
cluded in the study. A statistical summary of the data obtained is given in
Table 25. An examination of these data shows that CEC had no significant effect
in determining the uptake of Cd by corn.
Haq et al. (1980) studied the effect of various soil factors on Cd concen-
tration in Swiss chard in a greenhouse study involving 45 Ontario surface soils.
These soils ranged in pH from 5.2 to 7.9, in organic matter content from 1.4 to
17.0% and in CEC from 5.4 to 67.4 meq/100 g. In this study the Cd concentra-
tion in Swiss chard was associated with the organic matter content of the soil
but not with the CEC at the 0.05 level of probability. Some of the statistical
findings are given in Table 26. Soil CEC was also relatively unimportant as
an estimator of the Zn concentrations of plants in this study.
Keeney et al. (1980) point out the difficulties encountered in studies of
this nature in their statement, "When a number of soils are used, the role of
the increasing content of a certain soil parameter may be obscured by a variation
in another parameter." Furthermore, most experiments show that where CEC has
been changed by adding materials to a soil, it may have some influence on con-
centration of Cd and Zn in plant tissue. Thus, the influence of CEC may not
be as important as other factors in determining the concentration of Cd and
Zn in plants.
21
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Indications are that CEC is bejst viewed as a general, but imperfect, indi-
cator of the soil components that limit the solubility of Cd and Zn (i.e., or-
ganic matter, clays, and hydrous oxides of iron, aluminum and maganese) instead
of a specific factor in the availability of these'metals. The reason is that
less than 1 percent of the total Cd and Zn applied to soils in sludge is found
in the exchangeable form (Silviera and Sommers, 1977; Latterell et_ al., 19-78).
Limited evidence indicates that most of the Cd in most sludges is in a form
exchangeable with radioactive Cd added in solution even though it is not ex-
changeable in the usual sense of an exchangeable cation. Such isotopically
exchangeable Cd is probably the principal source of the Cd absorbed by plants.
Other Soil Factors
Several studies have evaluated the effect of nitrogen, phosphorus and potas-
sium fertilizers on the uptake of Cd and Zn by plants grown on metal-treated soils.
Many studies on the effect of type of nitrogen fertilizer have shown that the Zn
concentrations in plants are higher where the nitrogen is supplied as ammonium
than where it is supplied as nitrate. This effect is believed to be due to
a combination of several effects of ammonium and nitrate behavior on soil pH:
(1) ammonium is oxidized microbiologically to nitrate throughout the soil with
generation of acidity, (2) roots take up more equivalents of ammonium than of
anions, which lowers the pH of the soil immediately adjacent to the roots, and
(3) roots take up more equivalents of nitrate than of cations, which raises the
pH of the soil in the immediate vicinity of the roots (Smiley, 1974; Viets et
al., 1957; Giordano .et al., 1966).
Williams and David (1976) grew wheat on soils which had become enriched in
Cd from superphosphate application and found that fertilization with ammonium
nitrate increased the concentration of Cd in wheat. Soon et al. (1980) found
increased Cd and Zn concentrations in bromegrass as a result of ammonium nitrate
fertilization.
Williams and David (1977) evaluated the role of phosphorus fertility and
placement of applied Cd on Cd uptake by plants. This work indicated that, because
plant roots proliferate more in soil regions of greater fertility, plants absorb
more Cd if it is present in the soil region of greater fertility.
A study by Haghiri (1976) evaluated the relative effects of use of potassium
and calcium hydroxides for adjusting soil pH. Soybeans were grown, in a Canfield
silt loam which had been leached with hydrochloric acid to remove .exchangeable
cations, and then treated with calcium or potassium hydroxide to adjust the
exchangeable cations and pH. A Cd salt was added at 14.3 mg of Cd/kg of soil.
By comparing calcium- and potassiumLtreated soils at similar pH values, it was
observed that the Cd level in soybean shoots was lower with potassium than with
calcium. This difference might'be explained by the greater affinity of calcium
than of potassium for Cd sorption sites in the soil, resulting in higher soluble
Cd in the soil solution when calcium is the dominant cation present.
When sewage sludge is applied to cropland, the amounts of Cd applied are
normally smaller than the amounts of Zn, copper and nickel and much smaller than
the amounts of organic carbon, nitrogen and phosphorus applied therewith. The
22
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other metals added or present in the soil may affect the behavior of Cd in soil-
plant systems by (1) competing with Cd for metal sorption sites in the soil,
(2) competing with Cd for uptake by plants or translocation within plants or
(3) causing toxicity to the plants.
Most metal interaction experiments have been conducted under greenhouse con-
ditions. One example is the high-Zn, low-Cd Waukesha sludge studied by Cunning-
ham et al. (1975a). Zn toxicity occurred at very low soil Cd, and little Cd was
taken up by the plants. Cunningham e_t al. (1975b) added metal salts to sludge-
treated soils and found that additions of copper increased the concentration of
Cd in corn seedlings. Bingham ^t aJL. (1979) found that the concentration of
Cd in the grain of wheat grown on an acid soil was reduced by adding Zn but
was increased by adding copper. In the same soil after treatment with calcium
carbonate, the concentration of Cd was reduced by adding Zn and increased by
adding copper and nickel. Chaney and Hornick (1978) and Chaney and White (1979)
reported the results of a Cd-Zn study with soybeans and oats grown on Sassafras
sandy loam adjusted to pH 5.5 or 6.5. They found that the Cd concentration in
the plants increased linearly with the concentration of Cd in the soil within
each Zn level. With large additions of Zn and small additions of Cd, soybean
yield was severely reduced, and the concentration of Cd in the crop was not
appreciably increased. Haghiri (1974) obtained similar results.
Additional studies have examined interactions of Cd and Zn in nutrient
solutions to characterize plant properties as opposed to soil-plant properties.
Cataldo and Wildung (1979) found that Zn was a competitive inhibitor of Cd
absorption by soybean roots during short-term isotopic studies at low concen-
trations of soluble Cd (less than 1 micromolar). In studies of Cd absorption
by Romaine lettuce, Zn significantly inhibited Cd translocation from roots to
shoots when plants were grown for 3 weeks in nutrient solutions (Chaney and
White, 1979). Behel and Giordano (unpublished data) measured Zn uptake by
rice seedlings grown in solutions varying in Cd concentration. Absorption of
Zn after intervals ranging from 6 to 72 hours decreased in roots with increasing
Cd level while concentrations in the shoots were unaffected.
Extractable Metals
Various chemical extractants have been employed to provide an index of the
availability to plants of Cd and Zn in sludge-treated soils. The amounts of Cd
and Zn extracted invariably fail to provide a satisfactory index of the Cd and
Zn concentrations in plants on some soils when the extractants are used on a
large enough number o'f soils with different chemical characteristics. There
has been some success in obtaining a correlation between metal concentration in
plant tissue and extractable metal for a given plant species in a limited number
of soils (Bingham et_ ajL. , 1975; Lagerwerff-, 1971; Jones jet_ ail.., 1975). Recent
studies with 46 Cd- and Zn-contaminated soils and nine different chemical extract-
ants showed that extractable metal alone was not a good index of the concentra-
tion of Cd and Zn in the test plants (Haq ^t aj.., 1980). However, a combination
of two variablesammonium acetate-extractable Zn and soil pH yielded a good
index of the concentration of Zn in the test plants.
23
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CROP RESPONSE TO CADMIUM AND
ZINC IN SINGLE AND REPEATED
APPLICATIONS OF SLUDGE
The previous sections of this report have summarized the influence of sludge,
plant and soil factors on the Cd and Zn concentrations found in plants grown on
soils treated with sludge. The discussion emphasized the response of plants to
sludge-borne Cd and Zn rather than the effect of time following sludge applica-
tion. This section of the report will address two questions: (1) Do the same
metal concentrations in plants result; from equal total applications of sludge-
borne Cd and Zn in (a) a single sludge application and (b) sludge applications
repeated over a period of years? (2);Do the concentrations of Cd and Zn in crops
change with time after termination of! sludge applications to soils? These ques-
tions represent two different ways of addressing the change of availability of
sludge-borne Cd and Zn with time after application. The first relates to esti-
mating long-term crop responses from short-term responses on the assumption that
the availabilities of Cd and Zn do nop change with time.
Field experiments with sludge typically include a control treatment in which
no sludge is added along with one or more additional treatments in which sludge
is added, each treatment being applied to replicated plots. Each plot designated
to receive a particular treatment receives the assigned quantity of sludge each
year for a number of years. The data obtained on Cd and Zn can be expressed in
several ways, the simplest being graphs of the concentrations of Cd and Zn in
the plants vs. the quantities of sludge or metals applied annually. If the
effect of the Cd and Zn in one application disappears completely before the
next is added, the concentrations of the metals in the crops will remain the
same from year to year except for the effect of other factors. If the effect
of the Cd and Zn in individual annual applications does not disappear in the
course of a year but is dissipated over several years, the concentrations of
Cd and Zn in plants on plots that receive a given application of slxidge each year
will increase somewhat with time and |eventually will reach a constant level for
each, metal. And, if the effects of the applied metals do not decrease with time
after application of sludge, the concentrations of Cd or Zn in the plant tissue
associated with a given total application of Cd or Zn will be the same, whether
the metals have been applied in a single quantity in any year of the experiment
or in smaller quantities in two or more years. For example, in the model in
which the concentrations of Cd and Zn in plants increase linearly with the quan-
tities added and in which equal quantities are added each year, a plot of the con-
centration of Cd or Zn in the plants against the total quantity added will be
represented by a single straight line (Figure 2-B), and the increase in Cd or Zn
content in the plants per unit of metal added per year will be twice as great in
24
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the second year as in the first, three times as great in the third year as in
the first, and so on (i.e., interval D^ = D£ = D3 in Figure 2-A). This model
has been employed in some health-related projections as a very conservative
means of estimating the increases in concentrations of certain metals to be ex-
pected in plants grown on soils receiving repeated applications of sludge over
a period of years on the basis of the increases in concentration of the metal
or metals observed in the year in which a single quantity of sludge is applied.
Parenthetically, it should be emphasized that the model represented by
Figure 2 refers to hypothetical conditions in which soil pH and other factors
remain constant from year to year. Environmental factors vary from one year to
another but show no significant trend over a long period of years. In many non-
calcareous soils, however, the pH changes significantly with time, particularly
where sludge is applied, and this may have marked effects on the concentrations
of Cd and Zn in plants. Maintaining the soil pH at an approximately constant
value in such soils under field conditions is difficult, both practically and
experimentally.
If the availabilities of sludge-borne Cd and Zn decrease with time after
application, as has been found when micronutrients are added as fertilizers, the
cumulative effect of repeated applications will be less than the product of the
effect in the first year and the number of years the sludge has been applied.
These circumstances are represented by the model in Figures 3-A and 3-B, where
the concentrations of the metals in the plants are still assumed to increase
linearly with the quantities added to the soils.
If the relationship of metal concentration in the plants versus quantity
applied exhibits saturation effects in the plants, or if adding a calcareous
sludge to an acid soil causes a considerable increase in soil pH, the curves
will be concave downward. Under these circumstances also, the cumulative effect
of repeated applications generally will be less than the product of the effect in
the first year and the number of years the sludge is applied.
If the availabilities of sludge-borne Cd and Zn increase with time as a
result of an increase in soil acidity, different situations are theoretically
possible. If the increase in acidity is independent of the quantity of sludge
applied, intervals D£ and 03 in Figure 2-A might exceed interval Dj_. A more
likely situation is one in which the sludge contributes to the increase in acid-
ity. The lines in Figure 2-A might then be concave upward because large addit-
ions of sludge would produce greater acidification than would small additions.
The cumulative effect of repeated applications could then be greater than the
product of the effect in the first year and the number of years the sludge is
applied.
The value of the effects of single additions on the Cd and Zn content
of plants as a basis for estimating the cumulative effects of repeated additions
has been debated, and various views are held. The data used in this report to
illustrate the importance of single versus repeated applications of metals
(Hinesly et al., 1976, 1977; Baker et^ al., 1979a, 1979b; Dowdy et al., 1977;
Pietz et^ jil., 1980; and Giordano j|t^ _al., 1979a) have been derived from field
experiments in which a number of rates of annual application were repeated
on their respective plots each year. In these experiments, single applications
25
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were made only in the first year, and a fresh batch of sludge was obtained for
use in each succeeding year. In such experiments, the cumulative application
is approximately proportional to the annual application, and the results may be
affected by year-to-year variations iin sludge composition, soil pH and environ-
mental conditions.
Single And Repeated Additions Of Sludge-Borne Cadmium And Zinc
The response to a single application of Cd and Zn in sewage sludge has been
studied with numerous crops, including vegetables (Tables 3, 15, 16 and 19),
corn (Tables 17, 18, 20, 21, 27 and 29), oats (Tables 15, 28 and 30), soybeans
(Tables 15, 16, 28 and 30) and sorghum (Tables 28 and 30). The data indicate
that concentrations of both Cd and Zn in vegetative plant parts tend to increase
with increasing rates of metal addition. Although exceptions can be found (e.g.,
Zn in oat straw), the absolute concentrations of Cd and Zn are increased to a
greater extent in the leaves than in the grain of corn, sorghum, soybeans and
oats. The relative increase in metal concentration in plants with successively
greater quantities of sludge added in a single application is generally greater,
for Cd than for Zn. I
To compare the effects of a single addition of sludge-borne Cd and Zn in a
given year with the cumulative effects of additions that are repeated in succes-
sive years, an experiment must be continued for,two or more years. Only a few
such experiments have been carried out. Representative data obtained from them
will be presented and discussed.
The available evidence indicates the existence of a range of effects of re-
peated additions of Cd in sewage sludge. At the one,extreme are marked effects
in which the increase of Cd concentration in plants grown at the conclusion of
a period of years in which sludge has been added in annual increments is essen-
tially the same as the increase expected if all the sludge had been applied in
a single addition in the final year.3 Data obtained by Pietz et ajL. (1979) are
an example. These investigators found that the concentration of Cd in leaves of
corn grown on calcareous strip mine spoil increased-markedly as repeated applica-
tions of sludge were made over a period of 6 years (Table 31). The results seem
to approach those postulated in the [hypothetical model in Figure 2 in which the
effectiveness of applications made in the first and succeeding years does not de-
crease with time (although the soil ipH decreased somewhat through the years).
The rate of increase of Cd concentration in the corn leaves per unit of Cd added
in the sludge was 0.31 for the single addition of sludge and 0.30 for the re-
peated additions (Table 33).
3In the experiments available, the effect of single additions was measured in
the first year of the experiment, and the effect of repeated additions was
measured in later years after repeated additions had been made; hence, the
comparisons of the effects of single vs. repeated additions of sludge are not
independent of the effect of years. If the experiments had been designed to
make the comparisons of interest to EPA at this time, the single additions
would be made in the year their effects are to be compared with those of re-
peated additions.
26
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At the other extreme are limited effects in which the increase of Cd con-
centration in plants grown at the conclusion of a period of years in which sludge
has been added in annual increments is much smaller than the increase expected
if all the sludge had been added in a single application in the final year.
Work by Wolf and Baker (1980) provides an example (Table 32). In this experiment
on a neutral, noncalcareous, silt loam soil, the concentration of Cd in leaves
of corn increased to only a relatively small degree with repeated additions of
sludge. The rate of increase of Cd concentration in the corn leaves per unit of
Cd added in the sludge was 0.20 for the single addition of sludge and 0.09 for
the repeated additions (Table 33).
Tables 31 to 33 provide information on Zn as well as that just described
for Cd. In both experiments, the increase of Zn concentrations in the plants
at the conclusion of a series of annual additions of sludge was much smaller than
the increase expected if all the sludge had been added in a single application
in the final year.
Additional observations on the effects of single vs. repeated additions of
sludge on the Cd concentrations in corn leaves, stover and grain have been made
in published data by Hinesly et al. (1979c) , Dowdy _ejt al. (1977) , Giordano and
Mays (1977) and Soon et al. (1980) as well as in unpublished data by Hinesly
et al. (1979b), Giordano e_t al. (1979a) and Wolf and Baker (1980). These obser-
vations further illustrate the range of effects that may be found.
Improved quantification of the effects of single vs. repeated additions of
sludge in individual experiments is desirable, and further information is needed
to provide a reliable basis for predicting the effects that will occur "under dif-
ferent circumstances. There is no doubt that plant species respond differently
with regard to Cd uptake when sludge-borne Cd is applied to-soils. It is also
quite clear that soil pH has a marked effect on the Cd concentration in plants.
Information is not available at this time, however, to determine whether crop
species and soil.pH alter the cumulative effect of repeated Cd applications on
plant Cd as much as they influence the effect of a single application. It does
seem probable that most cumulative effects will fall within the wide range re-
ported here regardless of plant species or soil pH. The data available thus far
do not provide a basis for predicting the cumulative effects of repeated Cd ad-
ditions in sludge on the Cd content of plants. The data on cumulative effects
of repeated additions of Zn suggest that the range of values may be slightly
narrower than with Cd but that in most cases the trends with Zn are similar to
those with Cd.
Availability Of Sludge-Borne Cadmium And Zinc To Plants After Termination
Of Sludge Applications To Soils
Seasonal variations in soil and environmental conditions influence the con-
centrations of Cd and Zn in all crops. Nonetheless, data from controlled stu-
dies indicate that, in at least some instances, Cd applied to noncalcareous
soils in sludge may remain available to plants for a number of years after sludge
application has ceased (Tables 17, 34-39).
27
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Studies by Baker et. al. (1979a, 1979b) and Hinesly et al. (1979d) have
shown that Cd concentrations in corn grain, wheat grain, soybean seed and pota-
toes remained above background levels for 4 years after the cessation of sludge
applications, while data by Hinesly &t_ al. (1979c) indicate that concentrations
of Cd in corn grain returned to background levels within a 4-year period.
Other data from field studies demonstrate the residual effect of sludge
applications on Cd uptake by vegetable crops for up to 8 years after sludge ap-
plication (Tables 15, 19 and 38). A;greenhouse experiment performed by Chang
and Page (1979) also showed that Cd availability to radish crops grown on a
sludge-treated soil remained essentially the same for a 2-year period. Sim-
ilarly, sweet corn (Tables 36 and 38)! and bush beans (Table 38) showed elevated
Cd concentrations for 4 to 7 years after sludge applications were stopped. Con-
centrations of Cd were increased in both vegetative and reproductive plant parts
of both crops and were related to the cumulative amount of Cd applied.
Zn also has been shown to remain available to plants after the application
of sewage sludge to land has ceased (Hinesly e_t a^L., 1979d; Baker e_t £uL., 1979b).
Data on the residual availability of Zn and/or Cd to crops are available for
selected vegetables (Tables 15, 16, 19 and 38), soybeans (Tables 15 and 16),
potatoes (Tables 5 and 34), wheat (Tables 5 and 34), oats (Table 15), sweet
corn (Table 36 and 38) and field corn (Tables 17, 18, 20, 21, 34, 35 and 37).
The references cited indicate that the length of time sludge-derived Cd
and, Zn remain available to crops after sludge applications have ceased is in-
determinate. Although the evidence indicates that the concentrations of Cd and
Zn in plants may remain constant or may decrease for a period of years after
termination of sludge applications if the soil pH remains constant or is in-
creased, it is likely that the concentrations will increase if the soil pH
decreases.
Old sludge disposal sites have been used by Chaney and Hornick (1978), Otte
and LaConde (1978), Kirkham (1975), Ifyan (1977) and Webber et al. (1980) as an
additional source of information on the residual effects of sludge-borne Cd and
Zn on plants. For example, Chaney and Hornick (1978) grew lettuce, Swiss chard,
soybeans, oats and orchardgrass in 1976 on soils that had received sludge from
1961 to 1973. The total quantity of Cd in the soil was 2.8 mg/kg, and all crops
grown on the sludge-treated soil showed higher concentrations of Cd than did
the crops on the controls at the same soil pH. Table 39 shows the Cd and Zn
concentrations found in Swiss chard and oats grown on soils used for sludge dis-
posal by six cities in northeastern United States.
One of the limitations associated with data from old sludge-disposal sites
is that accurate records of the rates and frequencies of sludge application and
sludge composition are not available^ The findings by the investigators cited,
however, indicate that Cd applied to , soils in the form of sludge remains avail-
able to crops for an indefinite time after termination of sludge applications.
In summary, the information presented indicates that factors such as soil
and sludge properties and plant species and cultivars influence the concentra-
tions of Cd and Zn in plants following either a single application or repeated
28
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applications of sludge to soils. Most data indicate that Gd and Zn concentra-
tions in plants increase with the quantities of these elements added in single
or repeated applications of sludge to soils, but some studies, especially those
on calcareous soils and those in which assays were made of plant tissues such
as corn grain that tend to exclude Cd, have shown no significant correlation
between amounts of metal applied and concentrations in the plants. Similarly,
the metal concentrations in plants may or may not increase significantly with
the cumulative metal input to soils over a period of years during which repeated
applications have been made. The seeming contradictions are probably related
to (1) differences in the chemical, physical and biological properties of the
soils receiving the sludge-borne Cd and Zn, (2) differences in the chemical
properties of the sludge applied, differences in plant species and variety
tested as well as differences in the plant part used to evaluate the response
(vegetative parts are nearly always more responsive than the fruit or seed) and <
(4) variations in other factors including climate and management.
In view of the effects of single and repeated additions of sludge-derived
Cd and Zn on the content of these metals in plants, the residual effects after
sludge applications have ceased, and the effects of soil pH on the availability
of these metals to plants, it seems evident that considerable increases in con-
centration of Cd and Zn in many crops cannot be avoided when sludges high in
these metals are applied unless the total amounts of the metals supplied in
single and repeated additions are limited and unless the soil reaction is main-
tained near or above neutrality. Even at a soil pH of 6.5, the Cd added in many
sludges is sufficient to increase the Cd concentration in most crops.
29
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LITERATURE CITED
Baker, D. E.;, and M. C_. Amacher. 1979b. Unpublished data. Dept. of Agronomy,
Pennsylvania State University, University Park, Pennsylvania.
Baker, D. E., M. C. Amacher, and R. M. Leach. 1979a. Sewage sludge as a source
of cadmium in soil-plant-animal systems. Environ. Health Perspect. 28:45-49.
Bates, T. E., Y. K. Soon, and A. Haq. 1979. Unpublished data. Dept. of Land
Resource Science, University of Guelph, Guelph, Ontario.
Baxter, J. C. 1980. Unpublished data from Metropolitan Denver Sewage Disposal
District No. 1. Denver, Colorado. '
Berggren, B., and S. Oden. 1972. Analyresultat Rorande Fung Metaller Och Klorerade
Kolvaten. I. ROtslam Eran Svenska Reningsverk. 1968-1971. Institution fiir
Markvetsenskap Lantbrukshogskolan, Uppsala, Sweden.
Berrow, J. L., and J. Webber. 1972. Trace elements in sewage sludges. J. Sci.
Food Agric. 23:93-100.
Bingham, F. T. 1979. Bioavailability of Cd to food crops in relation to heavy
metal content of sludge-amended soil. Environ. Health Perspec. 28:39-43.
Bingham, F. T., A. L. Page, R. J. Mahler, and T. J. Ganje. 1975. Growth and
cadmium accumulation of plants grown on a soil treated with a cadmium-enriched
sewage sludge. J. Environ. Qual. 4 j: 207-211.
Bingham, F. T., A. L. Page, G. A. Mitchell, and J. E. Strong. 1979. Effect of
liming an acid soil amended with sewage sludge enriched with Cd, Cu, Ni, and
Zn on yield and Cd content of wheat grain. J. Environ. Qual. 8:202-207.
Blakeslee, P. A. 1973. Monitoring considerations for municipal wastewater
effluent and sludge application to the land. pp. 183-198. In Recycling
Municipal Sludges and Effluents on Land. Nat. Assoc. State Univ. and Land-
Grant Colleges, Washington, D.C.
Boggess, S. F., S. Willavize, and D. E. Koeppe. 1978. Differential response
of soybean varieties to soil cadmium. Agron. J. 70:756-760.
Buchauer, M. J. 1973. Contamination of soil and vegetation near a zinc smelter
by zinc, cadmium, copper, and lead. Environ. Sci. Technol. 7:131-135.
Cannon, H. L. 1955. Geochemical relations of zinc-bearing peat to the Lockport
Dolomite, Orleans County, New York. Geol. Survey Bulletin. 1000-D:119-185.
30
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Cartright, B., R. H. Merry, and K. G. Tiller. 1976. Heavy metal contamination
of soils around a lead smelter at Port. Pirie, South Australia. Australian
J. Soil Res. 15:69-81
Cataldo, D. A., and R. E. Wildung. 1979. Soil and plant factors influencing the
accumulation of heavy metals by plants. Environ. Health Perspect. 27:149-159.
Cavallaro, N., and M. B. McBride. 1978. Copper and cadmium adsorption character-
istics of selected acid-and calcareous soils. Soil Sci. Soc. Am. J. 42:550-555.
Chaney, R. L. and W. A. Feder. 1980. Unpublished data. SEA-AR-U.S. Department
of Agriculture, Beltsville, Maryland.
Chaney, R. L., and S. B. Hornick. 1978. Accumulation and effects of cadmium on
crops, pp. 125-140. _In Proc. First Int'l. Cadmium Conf., Metals Bulletin,
Limited. London.
Chaney, R. L., P. T. Hundemann, ₯. T. Palmer, R. J. Small, M. C. White, and A. M.
Decker. 1978. Plant accumulation of heavy metals and phytotoxicity resulting
from utilization of sewage sludge and sludge compost on cropland, pp. 86-97.
In. Proc. Natl. Conf. on Composting Municipal Residues and Sludges. Information
Transfer, Inc., Rockville, Maryland.
Chaney, R. L., and M. C. White. 1979. Zinc, Mn, and Cd interations and their
effect on Cd uptake and translocation by lettuce, oat and soybean. Am. Soc.
Agron. Abstracts. p. 27.
Chang, A. C., and A. L. Page. 1979. Effects of repeated soil application of
sludges on the Cd and Zn levels of affected vegetable crops. Final Report.
Wastewater Solids Management Program, Los Angeles/Orange County Metropolitan
Area. University of California, Riverside, California.
Chang, A. C., A. L. Page, L. J. Lund, P. F. Pratt, and G. R. Bradford. 1979.
Land application of sewage sludgea field demonstration. Final Report.
Regional Wastewater Solids Management Program, Los Angeles/Orange County
Metropolitan Area. University of California, Riverside, California.
Cunningham, J. D., D. R. Keeney, and J. A. Ryan. 1975a. Yield and metal compo-
sition of corn and rye grown on sewage sludge-amended soil. J. Environ. Qual.
4:448-454.
Cunningham, J. D., J. A. Ryan, and D. R. Keeney. 1975b. Phytotoxicity in and
metal uptake from soil treated with metal-amended sewage sludge. J. Environ.
Qual. 4:455-460.
Davis, J. A., R. 0. James, and J. 0. Leckie.
plexation at the oxide-water interface I.
layer properties in simple electrolytes.
1978. Surface ionization'and corn-
Computation of the electrical double
Colloid and Interface Sci. 63:480-499.
31
-------
Decker, A. M., C. H. Darrah, J. R. Hall, E. Strickling, J. P. Davidson, R. C.
Hammond, S. B. Mohanty, R. L. Chaney, and J. J. Murray. 1978. Feasibility
of using sewage sludge for plant and animal production. Final Report for
1976 and 1977. Submitted to Washington, D.C., Suburban Sanitary Commission.
195 pp.
Decker, A. M., C. H. Darrah, D. J. Wehner, E. Strickling, M. F. Rothschild, L. R.
Gouin, C. B. Link, J. B. Shanks, J. T. Davidson, R. C. Hammond, S,, B. Mohanty,
R. L. Chaney, J. J. Murray, D. L. Kern, and T.:S. Rumsey. 1980. Feasibility
of using sewage sludge for plant arid animal production. Final Report for 1978
and 1979. Submitted to Washington,1 D.C., Suburban Sanitary Commission. 222 pp,
DeVries, M. P. C., and K. G. Tiller. 1978. Sewage sludge as a soil amendment
with special reference to Cd, Cu, Mn, Ni, Pb and Zn comparison results from
experiments conducted inside and outside a glasshouse. Environ. Poll. 16:
231-240.
Dijkshoorn, W., and J. E. Lampe. 1975. Availability for ryegrass of cadmium and.
zinc dressings of sewage sludge. Neth. J. Agric. Sci. 23:338-344.
Doty, W. T., D. E. Baker, and R. F. Shipp. 1977. Chemical monitoring of sewage
sludge in Pennsylvania. J. Environ. Qual. 6:421-426.
Dowdy, R. H., C. E. Clapp, and W. E. Larson. 1977. The effect of wastewater
treatment on sludge-borne metal accumulation in corn leaf and grain tissue.
Am. Soc. Agron. Abstracts, p. 24.
Dowdy, R. H., and W. E. Larson. 1975.! The availability of sludge-borne metals
to various vegetable crops. J. Environ. Qual. 4:278-282.
Environmental Protection Agency. 1979. Criteria for classification of solid
waste disposal facilities and practices. Federal Register 44:53438-53468.
Epstein, E., and R. L. Jefferies. 1964. The genetic basis of selective ion
transport in plants. Ann. Rev. Plant Physiol. 15:169-184.
Farrah, H., and W. F. Pickering. 1977. The sorption of lead and cadmium species
by clay minerals. Australian J. Chem. 30:1417-1422.
Fox, M. R. S., R. M. Jacobs, A. 0. L. Jones, and B. E. Fry, Jr. 1979. Effects
of nutritional factors on metabolism of dietary cadmium at levels similar to
those of man. Environ. Health Perspect. 28:107-114.
Giordano, P. M., and D. A. Mays. 1977. Effect of land disposal application of
municipal wastes on crop yield and heavy metal uptake. EPA 600/2-77-014.
Giordano, P. M., and D. A. Mays. 1980. Crop utilization of nutrients from
municipal sewage sludge. I&EC Product Res. and Devel. (in press).
Giordano, P. M., D. A. Mays, and A. D.: Behel, Jr. 1979b. Soil temperature
effects on uptake of cadmium and zinc by vegetables grown on sludge-amended
soil. J. Environ. Qual. 8:233-236'.
32
-------
Giordano, P. M., J. J. Mortvedt, and D. A. Mays. 1979a. Residual effects of
municipal wastes on yield and heavy metal content of sweet corn and bush
beans. Agron. Abstracts (American Society .of Agronomy), p. 29.
Giordano, P. M., J. J. Mortvedt, and R. I. Papendick. 1966. Response of corn
(Zea mays L.) to zinc as affected by placement and nitrogen source. Soil Sci.
S"oc7 Amer. Proc. 30:767-770.
Gurnham, C. 'F., B. A. Rose, H. R. Ritchie, W. P. Fetherstone, and A. W. Smith.
1979. Control of heavy metal content of municipal wastewater sludge. Report
to Natl. Sci. Found. PB-295917. National Technical Information Service,
Springfield, Virginia. 144 pp.
Haghiri, F. 1974. Plant uptake of cadmium as influenced by cation exchange
capacity, organic matter, zinc, and soil temperature. J. Environ. Qual.
3:180-183.
Haghiri, F. 1976. Release of cadmium from clays and plant uptake of cadmium
from soil as affected by potassium and calcium amendments. J. Environ. Qual.
5:395-397.
Haq, A. U., T. E. Bates, and Y. K. Soon. 1980. Comparison of extractants for
plant-available zinc, cadmium, nickel, and copper in contaminated soils. Soil
Sci. Soc. Amer. J. (in press).
Hinesly, T. D., D. E. Alexander, K. Redborg, and E. L. Ziegler. 1980. Genetics
of Cd accumulation in corn (Zea mays L.). Unpublished data. Dept. of Agron.,
University of Illinois, Urbana, Illinois.
Hinesly, T. D., D. E. Alexander, E. L. Ziegler, and G. L. Barrett. 1978. Zinc
and cadmium accumulation by corn inbreds grown on sludge-amended soil. Agron.
J. 70:425-428.
Hinesly, T. D., R. L. Jones, J. J. Tyler, and E. L. Ziegler. 1976. Soybean yield
responses and assimilation of Zn and Cd from sewage sludge-amended soil. J.
Water Poll. Contr. Fed. 48:2137-2152.
Hinesly, T. D., R. L. Jones, E. L. Ziegler, and J. J. Tyler. 1977. Effects of
annual and accumulative applications of sewage sludge on assimilation of zinc
and cadmium by corn (Zea.mays L.) . Environ. S.ci. and Technol. 11:182-188.
Hinesly, T. D., K. Redborg, and E. L. Ziegler. 1979b. Compositional changes
in tissues of corn grown on sewage sludgeamended Blount silt loam. Unpub-
lished data. Dept. of Agron., University of Illinois, Urbana, Illinois.
Hinesly, T. D., E. L. Ziegler, and G. L. Barrett. 1979c. Residual effects of
irrigating corn with digested sewage sludge. J. Environ. Qual. 8:35-38.
Hinesly, T. D., E. L. Ziegler, and K. Redborg. 1979d. Uptake of zinc and cadmium
by soybeans and wheat from soil amended with sewage sludge several years previous
to the growing season. Unpublished data. Dept. of Agron., University of Illi-
nois, Urbana, Illinois.
33
-------
Hinesly, T. D., E. L. Ziegler, K. Redborg, and J. A. Ryan. 1979a. Effect of
soil pH on Zn and Cd uptake by corn | (Zea mays L.)- Unpublished data. Dept.
of Agron., University of Illinois,' Urbana, Illinois.
James, R. 0., and M. G. MacNaugh'ton. 1977. The adsorption of aqueous heavy metals
on inorganic minerals. Geochem. et Cosmochim. Acta 41:1549-1555.
Jones, R. L., T. D. Hinesly, E. L. Ziegler, and J. J. Tyler. 1975. Cadmium and
zinc contents of corn leaf and grain produced by sludge-amended soil. J.
Environ. Qual. 4:509-514.
Keeney, D. R., R. B. Corey, P. A. Helmke, L. L. Hendrickson, R. L. Korotev, M. A.
Turner, A. T. Shammas, K. D. Kunz, R. Fujii, and P. H. Williams. 1980. Heavy
metal bioavailability in sludge-amended soils. U.S. EPA Project R8046140.
Final Report (Unpublished).
Kinnlburgh, D. G., M. L. Jackson, and J. K. Syers. 1976. Adsorption of alkaline
earth, transition and heavy metal cations by hydrous oxide gels of iron and
aluminum. Soil Sci. Soc. Am. J. 40:796-799.
Kinniburgh, D. G., K. Sridhar, and M. L. Jackson. 1977. Specific adsoprtion of
zinc and cadmium by iron and aluminum hydrous oxides, pp. 231-239,, In M. N.
Hill (Ed.). Symposium Proceedings, The 15th Hanford Life Sciences Symposium
on Biological Implications of Metals in the Environment. USERDA, Nat. Tech.
Inform. Service, Springfield, Virginia.
Kirkham, M. B. 1975. Trace elements in corn grown on long-term sludge disposal
site. Environ. Sci. Technol. 9:765-768.
Konrad, J. G., and S. Kleinert. 1974. Removal of metals from waste waters by
municipal sewage treatment plants, 'pp. 2-7. In Surveys of Toxic Metals in
Wisconsin. Dept. of Natural Resources Tech. Bull. 74. Madison, Wisconsin.
Lagerwerff, J. V. 1971. Uptake of cadmium, lead and zinc by radish from soil
and air. Soil Sci. 111:129-133.
Lagerwerff, J. V., and D. L. Brower. 1974. Effect of a smelter on the agri-
cultural conditions in the surrounding environment, pp. 203-212. In D. D.
Hemphill (Ed.). Trace Substances in Environmental Health, VIII. Proceedings
University of Missouri 8th Annual Conference on Trace Substances in Environ-
mental Health.
Latterell, J. J., R. H. Dowdy, and G. E. Ham. 1976. Sludge-borne metal uptake
by soybeans as a function of soil cation exchange capacity. Commun. Soil Sci.
Plant Anal. 7:465-476.
Latterell, J. J., R. H. Dowdy, and W. E. Larson. 1978. Correlation of extract-
able metals and metal uptake of snap beans grown on soil amended with sewage
sludge. J. Environ. Qual. 7:435-440.
34
-------
Lue-Hing, C. 1979. Impact of toxics on characteristics of sludge. In Proc.
of the National Science Foundation Symposium on "Management of Toxic Materials
in Municipal Sludge." March 21-23, 1979, Miami, Florida.
Lund, L. J., and A. L. Page. 1980. Unpublished data. Dept. of Soil and Environ.
Sci., University of California, Riverside, California.
Mahler, R. J., F. T. Bingham, and A. L. Page. 1978. Cadmium-enriched sewage
sludge application to acid and calcareous soils: Effect on yield and cadmium
uptake by lettuce and chard. J. Environ. Qual. 7:274-281.
Mahler, R. J., F. T. Bingham, G. Sposito, and A. L. Page. 1980. Cadmium-enriched
sewage sludge application to acid and calcareous soils: Relation between treat-
ment, cadmium in saturation extracts, and cadmium uptake. J. Environ. Qual.
9:359-364.
Metcalf and Eddy, Inc.
782 pp.
1974. Waste Water Engineering. McGraw Hill, New York.
Milliken, C. R. 1961. Plant varieties and species in relation to the occurrence
of deficiencies and excesses of certain nutrient elements. Australian Inst.
Agric. Sci. 26:220-233.
Mulla, D. J., A. L. Page, and T. J. Ganje. 1980. Cadmium accumulations and bio-
availability in soils from long-term phosphorus fertilization. J. Environ.
Qual. 9:408-412.
Munshower, F. F. 1977. Cadmium accumulation in plants and animals on polluted
and nonpolluted grasslands. J. Environ. Qual. 6:411413.
NC-235.. 1976. Application of sludges and waste waters on agricultural land: A
planning and educational guide. B. D. Knezek and R. H. Miller (Eds.). North
Central Regional Research Publication 235. Ohio Agric. Res. and Devel. Center,
Wooster, Ohio. Reprinted by U.S. EPA as MCD-35 (1978).
Olson, B. H., V. P. Guinn, D. C. Hill, and M. Nassiri. 1978. Effects of land
disposal of secondary effluents on the accumulation of trace elements in
terrestrial ecosystems, pp. 362-376. JEn D. D. Hemphill (Ed.). Trace Sub-
stances in Environmental Health - XII. University of Missouri, Columbia,
Missouri.
Otte, A. D., and K. V. LaConde. 1978. Environmental assessment of municipal
sludge utilization at nine locations in the United States, pp. 133-146. In
R. C. Loehr (Ed.). Food, Fertilizer and Agricultural Residues. Ann Arbor
Sci. Publishers, Ann Arbor, Michigan.
Page, A. L., and F. T. Bingham.
Residue Rev. 48:1-44.
1973. Cadmium residues in the environment.
Patterson, J. W. 1975. Wastewater Treatment Technology.
Publishers, Ann Arbor, Michigan.
Ann Arbor Science
35
-------
Patterson, J. W. 1979. Parameters influencing metals removal in POTW's. pp.
82-90. In Proceedings of the 8th [National Conference on Municipal Sludge
Management: Impact of Industrial iToxic Materials on POTW Sludge. Information
Transfer, Silver Spring, Maryland.;
Pepper, I. L., and D. F. Bezedicek. 11980. Unpublished data.
Washington State University, Pullman, Washington.
Dept., of Agron.,
Pietz, R., T. D. Hinesly, K. Redborg, and E. L. Ziegler. 1980. Uptake of Cd
and Zn by corn from sludge-amended strip-mine spoil. Unpublished data.
Dept. of Agron., University of Illinois, Urbana, Illinois.
Reuss, J. 0., H. L. Dooley, and W. Gififfis. 1978. Uptake of cadmium from
phosphate fertilizers by peas, radishes and lettuce. J. Environ,, Qual.
7:128-133. >
Riffaldi, R., and R. Levi-Minzi. 1975. Adsorption and desorption of cadmium
on humic acid fractions of soil. 'Water, Air and Soil Poll. 5:179-184.
Ryan, J. A. 1977. Factors affecting plant uptake of heavy metals from land
application of residuals, pp. 98-105. In Disposal of Residues on Land.
Information Transfer, Inc., Rockville, Maryland.
Schwarz, K., and J. E. Spallholz. 1978. Growth effects of small cadmium supple-
ments in rats maintained under trace element-controlled conditions, pp. 105-
109. In Proc. First Intl. Cadmium Conf., Metals Bulletin, Limited. London.
Severson, R. C., and L. P. Gough. 19_76. Concentration and distribution of
elements in plants and soils near phosphate processing factories, Pocatello,
Idaho. J. Environ. Qual. 5:476-482.
Sheaffer, C. C., A. M. Decker, R. L. ^Chaney, and L. W. Douglass. 1979. Soil
temperature and sewage sludge effects on metals in crop tissue arid soils. J.
Environ. Qual. 8:455-459. !
Silviera, D. J., and L. E. Sommers. 1977. Extractability of copper, zinc, cad-
mium, and lead in soils incubated 'with sewage sludge. J. Environ. Qual.
6:47-52.
Sims, T., and F. C. Boswell. 1978. Effect of bentonite on plant availability
of sludge-borne heavy metals in soil. J. Environ. Qual. 7:501-505.
Singh, S. S. 1979. Sorption and release of Cd in some Canadian soils. Can. J.
Soil Sci. 59:119-130.
Smiley, R. W. 1974. Rhizosphere pH [as influenced by plants, soils, and nitrogen
fertilizers. Soil Sci. Soc. Am. Proc. 38:795-799.
Sommers, L. E. 1977. Chemical composition of sewage sludges and analysis of
their potential use as fertilizers. J. Environ. Qual. 6:225-232.
36
-------
Sommers, L. E., and D. W. Nelson. 1980. Unpublished data. Dept. of Agron.,
Purdue University, West Lafayette, Indiana.
Sommers, L. E., D. W. Nelson, J. E. Yahner, and J. V. Mannering. 1972. Chemical
composition of sewage sludge in selected Indiana cities. Indiana Acad. of Sci.
82:424-432.
Sommers, L. E., D. W. Nelson, and A. J. Yost. 1976. Variable nature of chemical
composition of sewage sludges. J. Environ. Qual. 5:303-306.
Soon, Y. K., T. E. Bates, and J. R. Moyer. 1980. Land application of chemically
treated sewage sludge: III. Effects on soil and plant heavy metal content.
J. Environ. Qual. 9:497-504.
Stover, R. C., L. E. Sommers, and D. J. Silviera. 1976. Evaluation of metals
in wastewater sludge. J. Water Pollut. Contr. -Fed.' 48:2165-2175.
Street, J. J., W. L. Lindsay, and B. R. Sabey. 1977. Solubility and plant
uptake of cadmium in soils amended with cadmium and sewage sludge. J.
Environ. Qual. 6:72-77.
Stumm, W., and J. J. Morgan. 1970. Aquatic Chemistry: An Introduction Empha-
sizing Chemical Equilibria in Natural Waters, pp. 205-213. Wiley-Inter-
science, New York.
Tabatabai, M. A., and W. T. Frankenberger, Jr. 1979. Chemical composition
of sewage sludges in Iowa. Iowa Agric. and Home EC. Exper. Sta. Res. Bull. 586.
U. S. Environmental Protection Agency. 1972. Montana area environmental pollu-
tion study, pp. 65-80. In Environ. Protection Agency, Office of Air Programs
Publi, AP-91. 179 pp.
Viets, F. G., Jr., L. C. Boawn and C. L. Crawford. 1957. The effect of nitrogen
and types of nitrogen carrier on plant uptake of indigenous and applied zinc.
Soil Sci. Soc. Amer. Proc. 21:197-201.
Walsh, L. M., D. E. Baker, T. E. Bates, F. C. Boswell, R. L. Chaney, L. A.
Christensen, J. M. Davidson, R. H. Dowdy, B. G. Ellis, R. Ellis, G. C. Gerloff,
P. M. Giordano, T. D. Hinesly, S. B. Hornick, L. D. King, M. B. Kirkham,
W. E. Larson, C. Lue-Hing, S. W. Melsted, H..L. Motto, W. A. Norvell, A. L.
Page, J. A. Ryan, R. P. Sharma, R. H. Singer, R. N. Singh, L. E. Sommers,
M. Sumner, J. C. Taylor, and J. M. Walker. 1976. Application of sewage
sludge to cropland: Appraisal of potential hazards of the heavy metals
to plants and animals. Council for Agric. Sci. & Technol. Rpt. 64. Re-
printed by the U.S. Environmental Protection Agency as MCD-33.
Webber, L. R., and E. G. Beauchamp. 1979. Cadmium concentration and distribu-
tion in corn (Zea mays L.) grown on a calcareous soil for three years after
three annual sludge applications. J. Environ. Sci. Health B14:459-474.
37
-------
Webber,'M. D., H. D. Monteith, and D, G. M. Corneau. 1980. Assessment of heavy
metals and PCB's at selected sludge application sites in Ontario. Canada
Ontario Agreement, Res. Rpt. (in press).
Williams, C. H.,- and D. J. David. 1973. The effect of phosphate on the cadmium
content of soils and plants. Australian J. Soil Res. 11:43-56.
Williams, C. H., and D. J. David. 1976. The accumulation in soil of cadmium
residues from phosphate fertilizers and their effect on the cadmium content
in the plants. Soil Sci. 121:86i-893.
Williams, C. H., and D. J. David. 1977. Some effects of distribution of cadmium
and phosphate in the root zone on, the Cd content of plants. Australian J.
Soil Res. 15:59-68.
Wolf, A. M., and D. E. Baker. 1980. Unpublished data. Dept. of Agron., Penn-
sylvania State University, University Park, Pennsylvania.
38
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TABLES AND FIGURES
Table 1. Concentrations of cadmium and zinc in the influent, effluent and
sludge of three activated sludge treatment plants of the Municipal
Sanitary District of Greater Chicago (Lue-Hing, 1979)
Metal concentration
Treatment
planta
Metal In influent In effluent In dry digested Sludge
sludge concentration
factor6
West-
nig/I
mg/1
mg/kg
Southwest (3009) t
Calumet
Hanover
(765)c
(20.4)d
> Cd
Zn
Cd
Zn
Cd
Zn
0.
0.
0.
0.
0.
0.
045
699
005
413
Oil
034
0
0
0
0
<0
0
.001
.034
.001
.009
.001
.002
248
2,917
56
2,391
72
710
5
4
11
5
6
20
,511
,173
,200
,789
,545
,882
a Number in parentheses is flow in thousands of m^/day.
b
Heavy industrial input with high metal content.
c
Heavy industrial input with low metal content.
Primarily domestic input with low metal content.
Q
Ratio of sludge concentration to influent concentration.
39
-------
Table 2. Concentrations of cadmium and zinc in sewage sludge
(Sommers, 1977)
Sludge
Metal
Type
Number
of samples
Concentration in dry sludge
Range Median . Mean
Cadmium
Zinc
Anaerobic
Aerobic
Othera
All
Anaerobic
Aerobic
Othera
All
98
57
34
189
108
58
42
208
1
3-3410
5-2170
4-520
3-3410
108-27800
108-14900
101-15100
101-27800
ng/Kg
16
16
14
16
1890
1800
1100
1740
106
135
70
110
3380
2170
2140
2790
Lagoon, primary and miscellaneous types of sludges.
40
-------
Table 3. Concentrations of cadmium and zinc in edible parts of vegetables grown
on sludge-treated soil at pH 4.6 and 6.7 (Giordano et al., 1979b)
Concentration of metals in edible
tissue of plants grown at indicated pH values
Plant
species
Lettuce
(cv. Romaine)
Cabbage
(var. capita ta)
Carrot
(var. sativa)
Pepper
(cv. California
Wonder)
Potato
(cv. Red Irish)
Tomato
(cv. Better Boy)
Egg Plant
(cv. Black
Beauty)
Sludge
added3
metric tons /ha
0
224
0
224
0
224
0
224
0
224
0
224
0
224
Soil
Zn
35
53
48
59
39
30
- 29
33
16
19
26
40
15
22
pH 4.6
Cd
0.88
2.25
0.19
0.35
0.96
7.29
0.24
0.97
0.11
0.10
0.52
1.04
0.54
1.64
Zn
mg/kg
31
51
29
46
22
29
24
29
^"~
Soil pH 6.7
Cd
0.78
1.78
0.16
0.19
0.71
1.25
0.19
0.98
__
The sludge added 403 kg of Zn/ha and 11.2 kg of Cd/ha to a Decatur silt loam
with a CEC value of 10 meq/100 g.
41
-------
CO
cu
rH
cd
4-1
CU
60
CU
*
i|_l
O
4J
CU
4-1
ti
O
U
CJ
a
H
N
»rt
a
cd
g
»3
H
rrj
cd
CJ
(U
4J
P*
O
H
O
CO
CO
a
CU
M
cd
CJ
cd
CJ
cd
0
4-1
o
H
4J
cd
o
H
rH
P.X-N
P. ON
cd ^*
ON
CU tH
60
3 *
co cd
H [ | i
O (U
4J 00
cJ p!
0
4, CM O CM vo vo
»' r-l lO r»« rH l~-
JO . .
3 O O O rH rH
ON
-------
Table 5. Cadmium uptake by sorghum, potatoes and wheat from sludge-
treated soils (Baker et al., 1979a, 1979b)
Cumulative
Cd addeda
kg /ha
0
4.1
8.3
16.6
Cadmium
concentration in indicated plant
Sorghum grain Potato
1975
0.035
0.470
0.876
0.855
1976
0.32
1.10
1.35
1.37
tubers
1977
0.21
0.88
1.02
1.45
Potato leaf
1977
1.92
7.45
10.95
17.47
tissues
Wheat
1976
0.07
0.89
1.73
1.91
grain
1977
0.06
0.60
1.00
1.42
Cd added in sludge in 1974 and 1975 to a silt loam soil with a CEC
of 12 meq/100 g. Soil pH levels were 6.6, 6.4, and 6.6 for 1975,
1976, and 1977, respectively.
43
-------
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r
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Table 9.
Response of corn inbreds to sludge-borne cadmium and zinc (Hinesly
et al., 1978)a
Metal concentration
in plant tissue
Metal
Metal
Cumulative
(1969-1975)
applied
During
growing
Leafb
1976
season
Soil
PH
Inbred
A
Inbred
B
Grainb
Inbred
A
Inbred
B
Zn
Cd
0
463
926
1852
0
24.8
49.5
99.0
Kg/na
0
69
137
273
0
4.8
9.6
19.1
7.4
7.6
7.3
7.0
7.4
7.6
7.3
7.0
16
43
62
193
0.9
12.0
36.9
62.9
mg/kg
15 30
36 41
48 47
103 70
<0.06 0.12
0.30 0.66
0.90 2.33
2.50 3.87
26
27
31
34
0.06
0.09
0.08
0.08
Data from 1976 growing season.
during the growing season.
Sewage sludge was applied by furrow irrigation
Inbreds for Zn data:
Inbreds for Cd data:
A = A619 and B = H99
A = B37 and B = R805
47
-------
Table 10. Effect of temperature on cadmium and zinc concentrations in
various parts of corn plants (Sheaf fer ^t aJ^., 1979)a
Zn
Soil
temperature
Op
C
16
22
27
35
Seedling
222b
25 3b
248b
300a
Ear
leaf
92d
109c
120b
143a
Grain
28d
32c
36b
40a
Stover
b
180b
163b
168b
226a
Seedling
0.74c
0.86b
0.76c
l.lOa
Cd
Ear
leaf Grain
0.29b 0.09
0.34a 0.08
0.31a 0.07
0.33a 0.10
Stover
1.09a
0.66b
0.72b
0.86b
Corn grown on a Sassafras sandy loam soil treated with 246 kg of Zn/ha and
0.9 kg of Cd/ha. Soil pH = 5.6. iCEC = 5.6 meq/100 g.
Numbers in a given column followed by the same letter are not significantly
different by Duncan's Multiple Range Test (p <0.05).
48
-------
Table 11. Effect of season (year) on cadmium and zinc concentration
in several crops after one application of sewage sludge in
1975
Metal concentration in plant
Metal
Zn
Cd
Crop
Corna
Lettuce^
Pepper^
Corn3
Lettuceb
Pepperb
1975
116
92.8
4Q.O
0.33
5.33
0.91
cated year
1976
96
58.3
-
0.37
2.24
tissue in indi-
1977
30.0
0.64
aSheaffer et al. (.1979). The soil pH values were 5.6, 5.3, and 5.2
in 1975, 1976 and 1977, respectively.
bGiordano et al. (1979b). The soil pH values were 6.0, 6.1, and
6.0 in 1975, 1976 and 1977, respectively.
49
-------
Table 12. Cadmium in native vegetation from soils with different natural
levels of cadmium (Lund and Page, 1980)a
Total Cd
in soil
nig/kg
22
15
12
6
5.6
4.2
3.7
3.5
2.9
2.1
0.26
0.15
0.13
0.10
0.01
Soil
6.4
5.8
6.0
6.0
7.1
6.7
7.4
6.7
6.2
6.2
6.4
6.3
4.9
5.3
6.0
Cd concentration in
Wild oats
_
2.0
7.6
-
1 -
1.0
0.5
-
1.3
0.7
0.4
-
0.22
0.11
0.09
indicated plants
Mustard
. /],
2.0
-
4.0
0.5
1.0
1.6
3.6
0.14
0.39
0.27
aSoils and plants collected from Malibu Canyon,, California.
50
-------
Table 13. Cadmium concentrations in Swiss chard grown in the
greenhouse on soils containing different levels of
natural cadmium (Lund and Page, 1980)a
Soil
series
Hamb right
Los Osos
Saugus
Salinas
Castiac
Malibu
Millsholm
Soil
pH
-
6.8
7.1
5.7
6.7
6.0
5.7
6.4
Total soil
Cd
mg/kg
0.02
6.5
1.4
6.8
12.0
20.0
22.0
Plant
Cd
mg/kg
0.6
5.0
5.8
9.6
72.0
72.0
82.0
1Soils collected from Malibu Canyon, California.
51
-------
Table 14. Cadmium and zinc concentrations in surface soil and vegetation
adjacent to an industrial smelting complex (U.S. Environmental
Protection Agency, 1972)
Distance
from stack
Direction
from source
Metal concentra-
tion in soil
Cd
Zn
Metal concentration
in vegetation
Cd
Zn
km
0.65
1.3
4.0
7.3
Control
Northeast
East
Southwest
West
56
21
6.5
2.0
0.5
m.
g/kg
418 7.5
455 8.6
126 1.3
82 0.7
44 0.1
52
60
13
12
6.8
52
-------
Table 15. Concentrations of cadmium and zinc in lettuce, Swiss chard, soybean
grain and oat grain grown on sludge-treated soils (Decker et^ ail., 1978)
Metal
addition Limestone
Zn Cd addedb
kg /ha
0 0 No
Yes
Excess
74 0.7 Yes
No
148 1.4 Yes
No
296 2.8 Yes
No
Metal concentrations in indicated crops
Year
1976
1977
1978
1976
1977
1978
1976
1977
1978
1976
1977
1978
1976
1977
1978
1976
1977
1978
1976
1977
1978
1976
1977
1978
1976
1977
1978
Soil
PH
5.3
5.7
5.7
5.9
6.4
6.7
7.3
7.5
7.5
6.3
6.4
6.6
5.6
5.6
5.9
6.0
6.2
6.6
5.6
5.6
6.0
5.9
6.1
6.8
5.6
5.5
5.7
Zn in
lettuce
31.7
59.9
71.4
17.8
46.3
38.0
13.4'
38.8
24.5
26.3
61.7
48.9
44.9
108.9
101.0
30.1
69.2
55.3
41.7
96.6
101.0
47.9
80.3
58.7
72.9
148.0
147.0
Cd in
lettuce
0.80
0.94
0.56
0.41
0.76
1.36
0.33
0.44
1.83
0.54
0.85
0.59
1.53
2.16
1.18
0.71
1.05
0.59
1.28
1.61
1.02
1.31
1.19
0.49
1.70
2.43
0.98
Cd in
Swiss
chard
mrr 1 1,-i->
m& / K-&
1.03
0.71
0.73
0.33
-
0.29
0.26
_
1.21
0.81
2.68
3.52
1.64
0.73
2.31
4.55
-
1.98
0.98
-
3.76
1.64
Cd in
soybean
grain
0.34
0.05
_
0.14
0.05
-
0.28
0.05
_
0.11
0.11
_
0.24
0.07
_
0.19
0.13
_
0.21
0.08
_
0.20
0.08
-
0.23
0.09
Cd in
oat
grain
0.04
0.09
_
0.05
0.08
_
0.03
0.06
_
0.07
0.11
_
0.11
0.15
_
0.08
0.09
_
0.08
0.09
_
0.09
0.14
_
0.13
0.13
Heat-treated sludge was applied in 1976 to a Christiana fine sandy loam, CEC =
6.5 meq/100 g.
Dolomitic limestone was applied each year to maintain the soil pH at about 6.5.
Excess refers to the normal dolomitic limestone application plus an excess of
44 metric tons/ha.
53
-------
Table 16. Effect of soil pH on cadmium and zinc concentrations in crops grown in
1978 on soils treated with Nu-Earth sludge (Decker et al., 1980)
Metal concentrations in indicated crops
Metal
applied3
Zn Cd
Limestone
applied*3
Soil
pH Lettuce
Zn
Swiss
chard
Soybean
grain Lettuce
Cd
Swiss
chard
Soybean
grain
Kg/na
00-
Excess
83 4.2
208 10.5
-j.
416 21
5.7
6.7
7.5
6.4
6.7
6.6
6.9
6.3
6.7
71
38
24
91
73
192
98
222
112
98
39
40
296
96
427
122
383
169
in
46
43
40
56
52
68
57
72
71
&/ s-S
0.56
1.36
1.83
6.59
4.29
16.8
8.01
23.9
8.66
0.71
0.33
0.26
8'. 43
3.92
15.5
5.80
20.6
8.62
0.05
0.05
0.05
0.36
0.2.6
0.65
0.61
1.00
1.24
The experiment was carried out on a Christiana fine sandy loam, CEC = 6.5 meq/
100 g.
The amount of dolomitic limestone applied was based on a buffer method. Dolo-
mitic limestone was applied each year to maintain the soil pH at about 6.5.
"Excess" refers to the normal dolomitic limestone application plus; an excess
of 44 metric tons/ha.
54
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59
-------
Table 21. Concentrations of cadmium and zinc in corn grown on soils
treated with either sludge or metal salts (Baxter, 1980)a
; Metal concentrations in corn leaves^
Sludge
applied
metric
tons /ha
0
0
318
0
636
Metals applied
Zn
0
306
306
612
612
Cd
-kg/ha
0
4.9
4.9
9.7
9.7
Soil
1976
7.7a
7.6a
7.0a
7.5a
6.8b
PH
1979
7.7a
7.6a
7.4a
7.6a
7.3a
Zn
1976
22a
41ab
75c
53bc
126d
1979
35a
56b
54b
58b
56b
Cd
1976
1-rr i
t~S
0.23a
0.39ab
0,52b
0.58bc
0.72c
1979
0.44a
-
-
0.50a
0.85a
a Corn grown on Weld silt loam; CEC = 15 meq/100 g.
Values within a column followed by the same letter are not significantly
different at the 5% level according to Duncan's Multiple Range Test.
60
-------
Table 22. Influence of sludge additions and soil cation exchange
capacity on yield and concentrations of cadmium and zinc
in soybean shoots grown in the greenhouse (Latterell
et al., 1976)
Sludge
added
metric
tons /ha
0
23.3
46.7
Metal concentrations in
soybean shoots
CEC
meq/100 g
5.2
9.7
14.1
18.5
5.2
9.7
14.1
18.5
5.2
9.7
14.1
18.5
Yield
g/100 g of
soil
0.24
0.26
0.28
0.30
0.26
0.29
0.28
0.30
0.16
0.21
0.27
0.30
Cd
/n
mg/ Kg
0.16
0.16
0.19
0.26
0.29
0.30
0.34
0.36
0.54
0.39
0.48
0.31
Zn
33
34
37
. 24
83
70
62
59
163
139
118
98
61
-------
Table 23. Yield and cadmium content of greenhouse-grown oat shoots
as influenced by soil CEC (Haghiri, 1974)
CECfc
meq/100 g
17.1
18.9
23.1
26.9
30.5
Exchangeable
soil Cda
rag/kg
2.94a
2.90a
2.55b
2.34b
1.95c
Dry weight
of oat shootsa
g/pot
0.99c
1.34b
1.34b
1.66a
1.76a
Cd in oat
shoots3
mg/kg
13. 7a
12. 9a
11. Ob
9.5c
7.9d
aValues in a column followed by the same letter are not significantly different
at p = 0.05.
^The soil CEC was increased by adding muck, the pH was adjusted to 6.5 and Cd.
was added as CdCl2 at 20 mg/kg.
62
-------
Table 24. Effect of soil properties and calcium carbonate additions on cadmium
content of corn seedlings grown on sludge-treated soils (80 metric
tons/ha) in the greenhouse (Keeney _et_ al. , 1980)
Soil
series
' C
Sphagnum
Piano
Plainfield
Briggsville
Granby
Houghton
Kewaunee
Adolf
Poygan
Wausau
Clay
*
24
6
7
7
-
56
34
33
14
Organic
C
46.80
2.07
0.33
0.74
4.80
31.90
0.98
4.32
3.63
1.95
CEC
meq/
100 g
400
18
3
5
25
150
26
36
41
15
Soil pH in 0.
01 M CaCl2 Cd in corn seedlings
CaCOs Excess . GaC03 CaC03 Excess CaC03
added3 addedb added3 addedb
5.0
5.6
5.7
5.7
5.7
5.8
6.4
6.5
6.7
7.1
6.7
6.9
7.0
6.7
6.9
6.6
7.0
7.1
7.1
7.2
i
4.6
3.4
4-7
4.7
2.5
1.7
3.1
1.4
1.4
2.5
ng/kg
2.2
2.6
2.8
2.4
1.7
1.6
2.0
1.3
1.3
.2.3
Based on a lime requirement method.
CaCO, added in quantities found in a_ plus one CEC in excess (i.e., the soil was
calcareous).
c ;
Estimated CEC. These two soils were excluded from the statistical analysis shown
in Table 25.
63
-------
Table 25. Coefficients of determination (R2) for the regres-
sion of the cadmium concentration in plants on
selected properties of the eight mineral soils
shown in Table 24, and the significance of the re-
gression (F ratio) for individual properties in
different combinations (Keeney et al., 1980)
Crop
1st
2nd
3rd
1st
2nd
3rd
1st
2nd
3rd
1st
2nd
3rd
1st
2nd
3rd
F
Organic
C
4.89**
4.72*
5.80*
3.20
2.19
4.24*
3.27
2.59
4.16*
ratio for
Clay
0.62
0.61
1.82
0.00
0.59
0.05
0.09
0.97
0.07
indicated variables
CEC pH
13.08**
34.88
30.54**
14.20**
37.90**
29.98**
2.64 11.02**
1.40 31.40**
3.88 24.42**
12-. 41**
35.09**
27.06**
R2
0.04
0.04
0.15
0.12
0.23
0.48
0.10
0.22
0.43
0.12
0.22
0.47
0.12
0.23
0.48
*Significant at 0.05 probability level.
**Significant at. 0.01 probability level.
64
-------
Table 26.
Regression equations for estimating the concentration of
cadmium in Swiss chard using DTPA-extractable cadmium and
other soil characteristics as independent variables (Haq
et al., 1980)
Regression
step
1
2
3
4
5
6
7
a.
OM = organic
b ,
R2
0.347
0.622
0.720
0.766
0.805
0.813
0.824
matter;
Varia
adde
Cd
PH
PH
OM x
pH x
ble Final equation
id4* Coefficient
1.10
-12.1
2 0.825
Cd 0.00859
Cd -0.119
Cd2 -0.00537
OM x
Cd = DTPA
CEC -0.00267
extractable Cd.
F Ratio
13.3**
11.9**
10.2**
0.3
8.8**
4.0
2.4
65.
-------
0 1 2 3
Annual addition of metal
Year 1 = Year 2 = Year 3
_L
0 3 6 9
Cumulative addition of metal
Figure 2. Hypothetical relationships between the concentration of a trace metal
in plants and the quantity of the metal added to soil in three succes-
sive annual increments under circumstances in which the availability
of the metal to plants remains constant with time: A. Plot of concen-
tration in plants against quantity added annually. B. Plot of concen-
tration in plants against cumulative addition.
66
-------
o Contro1 9
0 1 ,2 3
Annual addition of metal
0
3 6
Cumulative addition of metal
Figure 3. Hypothetical relationships between the concentration of a trace metal in
plants and the quantity of the metal added to soil in three successive
annual increments under circumstances in which the availability of the
metal to plants decreases with time: A. Plot of concentration in plants
against quantity added annually. B. Plot of concentration in plants
against cumulative addition.
67
-------
Table 27. Effect of a single sludge application on cadmium concentrations
in corn
Crop
Corn3
Cornb
Cornc
Sludge A
Sludge B
Sludge C
Cd
applied
kg/ha
0
5.9
11.9
23.8
0
0.98
1.96
3.92
0
16
32
64
128
68
136
14
28
42
Soil
PH
5.9
6.8
6.4
6.1
7.8
7.7
8.0
8.0
6.0
6.7
7.0
7.1
7.3
6.5
6.6
7.2
7.3
7.4
Concentration of Cd
Leaves
HI O" / Tr P"
0.11
2.67
4.06
2.89
0.34
0.32
0.75
1.45
0.42
1.07
1.55
2.04
1.66
5.08
7.81
1.13
1.62
0.92
in corn
Grain
0.06
0.14
0.18
0.20
0.06
0.12
0.12
0.21
<0.05
<0.05
<0.05
<0.05
<0.05
0.06
0.14
<0.05
<0.05
<0.05
aDowdy et al. (1977). Sandy soil, CEC =6.7 meq/100 g.
bPietz et al. (1979). Strip-mine spoil, CEC = 15 meq/100 g.
cSommers .et al. (1980). Silt Ipam soil, CEC = 23 meq/100 g.
68
-------
Table 28. Effect of a single sludge application on cadmium concentra-
tions in sorghum, soybeans and oats
Crop
Sorghuma
Soybeans"
Sludge A
Sludge B
Sludge C
Oatsb
Sludge A
Sludge B
Sludge C
Cd
applied
kg/ ha
0
0.86
1.57
2.26
0
16
32
64
128
68
136
203
14
28
42
0
16
32
64
128
68
136
203
14
28
42
Soil
pH
6.0
5.9
5.7
5.8
6.0
6.7
7.0
7.1
7.3
6.5
6.6
6.6
7.2
7.3
7.4
6.0 .
6.7
7..0
7.1
7.3
6.5
6.6
6.6
7.2
7.3
7.4
Cd concentration
plant tissue
Leaf
TO CT /1r cr
nig/ i&g
0.30
1.20
1.60
1.90
1.59
2.24
1.78
1.80
2.42
4.62
5.02
5.97
2.10
1.72
2.13
0.77C
1.14
1.64
1.96
3.11
8.96
17.22
17.22
0.96
0.82
1.07
in
Grain
0.10
0.10
0.09
0.05
0.41
0.51
0.75
0.78
0.93
2.07
3.31
3.36
0.48
0.55
0.52
0.16
0.49
0.76
0.84
1.66
1.65
3.42
3.42
0.24
0.29
0.39
aChang jet al. (1979). Sandy loam, CEC = 7 meq/100 g.
bSommers ejt al. (1980). Silt loam, CEC = 23 meq/100 g.
°Data for oat straw.
69
-------
Table 29. Effect of a single sludge application on zinc concen-
trations in corn plants
Soil
Zinc concentration in
plant tissue
Crop
a
Corn
Corn
Corn
Sludge A
Sludge B
Sludge C
Zn applied
kg /ha
0
31
62
123
0
14
28
57
0
381
762
1523
3046
106
213
291
582
1164
! PH
5.9
6.8
6.4
6.1
7.8
7.7
8.0
8.0
6.0
6.7
7.0
7.1
7.3
6.5
6.6
7.2
7.3
7.4
Leaf
13
29
44
50
15
34
43
80
37
40
62
69
77
50
49
44
37
53
Grain
mg/kg
29
28
27
27
5
23
34
36
13
14
19
19
16
21
22
23
18
12
a Dowdy ^t al. (1977). Sandy soil, CEC =6.7 meq/100 g.
b Pietz et al. (1979). Strip-mine spoil, CEC = 15 meq/100 g.
° Sommers et al. (1980). Silt loam soil, CEC = 23 meq/100 g.
70
-------
Table 30. Effect of a single sludge application on zinc
concentrations in sorghum, soybeans and oats
Crop
Zn
applied
Soil
PH
Cd concentrations in
plant tissue
Leaf
Grain
o
Sorghum
Soybeans
Sludge A
Sludge B
Sludge C
Oats
Sludge A
Sludge B
Sludge C
*>&/ net
0
46
80
114
0
381
762
1523
3046
106
213
320
291
582
1164
0
381
762
1523
3046
106
213
320
291
582
1164
6.0
5.9
5.7
5.8
6.0
6.7
7.0
7.1
7.3
6.5
6.6
6.6
7.2
7.3
7.4
6.0
6.7
7.0
7.1
7.3
6.5
6.6
6.6
7.2
7.3
7.4
mg/i
25
53
80
120
42
53
67
55
63
54
59
63
44
48
51
ioc
21
20
32
66
20
19
14
17
17
14
^S
17
23
20
31
39
44
47
44
59
42
47
46
46
42
43
30
30
35
39
51
37
34
32
25
28
28
Chang et al. (1979). Sandy loam, CEC = 7 meq/100 g.
Sommers et^ al. (1980). Silt loam, CEC = 23 meq/100 g.
Data for oat straw.
71
-------
Table 31. Concentration of cadmium and zinc in corn leaves and grain as affected
bv application of sewage sludge to calcareous strip mine spoxl (Pietz
y et al., 1979)
Metal addition
Annual
Year
Zn
Cd
Cumulative
Zn
Cd
Soil
pH
Metal concentrations in plant tissue
Leaves
Zn
kg/ha
1973
1974
1975
1976
1977
1978
1973
1974
1975
1976
1977
1978
1973
1974
1975
1976
1977
1978
1973
1974
1975
1976
1977
1978
0
0
0
0
0
0
14
64
64
75
119
84
28
128
126
139
238
167
57
255
253
278
475
334
0
0
0
0
0
0
1
5
4
4
7
6
2
10
9
9
14
12
4
21
18
18
28
23
0
0
0
0
0
0
14
78
142
217
336
420
28
156
282
421
659
826
57
312
565
843
1318
1652
0
0
0
0
0
0
1
6
10
14
21
27
2
12
21
30
44
56
4
26
44 .
62
90
113
7.8
8.0
7.8
7.7
7.2
7.3
7.7
8.0
7.7
7.7
7.5
7.5
8.0
8.1
7.6
7.8
7.0
7.4
8.0
8.1
7.5
7.6
7.3
7.2
15
13
21
33
33
49
34
43
74
109
81
114
43
51
93
124
132
201
80
72
121
191
200
317
Cd
0.34
0.29
0.12
1.42
1.94
1.91
0.32
0.78
1.84
6.15
5.60
7.20
0.75
1.47
3.90
8.50
15.53
16.95
1.49
4.06
7.45
22.59
28.72
33.68
Grain
Zn
15
19
18
20
25
27
19
28
29
32
33
37
22
33
32
35
39
44
26
32
37
41
45
51
Cd
<0.06
<0.06
0.08
<0.06
0.08
0.16
0.12
0.12
0.16
0.14
0.21
0.28
0.12
0.18
0.21
0.46
0.46
0.41
0.21
0.24
0.38
0.54
0.78
0.83
72
-------
Table 32. Concentration of cadmium and zinc in corn leaves and grain as affected
by sludge application to a.Murrill silt loama (Wolf and Baker, 1980)
Metal
Annual
Year
1974
1974
1975°
1976
1977
1978
Zn
0
74
74
74
74
74
Cd
0
4.1
4.1
4.1
4.1
4.1
addition
Cumulative
Zn
kg /ha
0
110
184
258
332
406
Cd
0
4.1
8.3
12.4
16.6
20.7
Soil
PH
6.7
7.2
7.2
7.1
7.1
7.1
Metal concentration
in indicated crops
Corn
1 Leaves
Zn
20
40
69
81
89
89
Cd
0.26
1.09
1.34
0.64
2.91
2.14
Grain
Zn
19
16
33
27
35
50
Cd
mgj
0.02
0.07
0.05
0.05
0.07
0.10
Soybeans
Leaves
Zn
/!,/>
rKg
39
48
55
62
74
56
Cd
0.10
0.66
0.55
0.75
1.27
1.02
Grain
Zn
41
48
53
61
61
65
Cd
0.10
0.64
0.68
0.49
0.50
0.74
Soil CEC = 13 meq/100 g.
The cumulative and annual applications of Zn in 1974 are shown to be unequal
because the experiment was started in 1972, and a total of 36 kg of Zn/ha was
applied in 1972 and 1973. The cumulative and annual applications of Cd in 1974
are shown to be equal because the sludge applied in 1972 and 1973 contained al-
most no Cd.
In 1975 the corn hybrid was changed from Pioneer 3773 to Pioneer 3780.
73
-------
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74
-------
Table 34. Concentration of cadmium in crops in four growing seasons after
final sludge application3- (Baker ^t al. , 1979a, 1979b)
Cd concentration in indicated crops
Year
1
2
3
4
5
6
Cd
addition
Annual Cumulative
0
4.1
0
4.1
0
0
0
0
0
0
0
0
- kg/ha
0
4.1
0
8.3
0
8.3
0
8,3
0
8.3
0
8.3
Corn
leaves
0.08
1.66
0.33
0.95
0.06
0.87
0.06
1.06
0.07
0.57
0.05
0.83
Corn Wheat
grain grain
_
0.015
0.065
0.007 0.07
0.036 1.73
0.004 0.06
0.033 1.00
0.010
0.039
_ _
_ _
Potato
tubers
-
_
-
0.32
1.35
0.21
1.02
1 -
-
_
lSilt loam soil; pH = 6.5; CEC = 13 meq/100 g.
75 ,
-------
Table 35. Concentrations of cadmium and zinc in corn leaves and grain
during applications|of sewage sludge and for four years after
the final sludge application3 (Hinesly et al., 1979c)
' Metal concentrations
Metal addition
Year
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
Annual
30.5
13.2
7.8
6.8
0
0
0
0
585
265
192
248
0
0
0
0
Cumulative
i _ /I
kg/ha
30.5
43.7
51.5
58.3
58.3
58.3
58.3
58.3
585
850
1042
1290
1290
1290
1290
1290
Corn
Control
Cadmium
0.5
0.5
0.3
0.1
0.7
0.3
0.3
0.4
Zinc
42
24
21
28
22
35
23
20
leaves
Sludge
7i
: mg/kg
11.6
10-.-4
2.5
0.9
1.9
1.3
1.3
1.9
112
85
58
55
63
38
36
25
in plant tissues
Corn
Control
0.15
0.15
0.16
0.18
0.15
0.14
0.10
<0.06
24
16
18
20
25
24
25
28
grain
Sludge
0.20
0.43
0.27
0.15
0.22
0.14
<0.06
. <0.06
32
28
36
27
29
26
25
26
Silt loam soil, pH = 7.3, CEC = 12 meq/100 g. The control plots
received no Cd or Zn.
76
-------
Table 36. Concentrations of cadmium and zinc in sweetcorn leaves and grain
during applications of sewage sludge and for four-years after the
final application of sludgea (Giordano et al., 1979a)
Metal concentration in corn tissue
Leaves
Metal addition
Year
1972
1973
1974
1975
1976
1977
1978
1979
1972
1973
1974
1975
1976
1977
1978
1979
Annual
10
10
10
10
0
0
0
0
360
360
360
360
0
0
0
0
Cumulative
1- n f-L, _
Kg/na
10
20
30
40
40
40
40
40
360
720
1080
1440
1440
1440
1440
1440
Soil pH
Cadmium
5.6
6.1 :
6.3
5.7
4.5
5.1
6.0
6.3
Zinc
5.6
6.1
6.3
5.7
4.5
5.1
6.0
6.3
Control
1.0
1.1
0.6
0.7
1.0
0.8
2.1
1.1
41
53
28
46
72
78
114
62
Sludge
added
4.1
7.9
5.4
7.0
5.9
5.8
9.2
5.5
97
241
250
400
497
906
724
434
Grain
Control
.
ing /kg
0.3
0.5
0.2
0.2
_
0.6
0.4
0.4
37
35
40
32
_
44
41
38
Sludge
added
1.2
1.0
0.7
1.2
1.2
0.9
1.0
44
61
75
64
_
70
71
65
Decatur silt loam; CEC = 10 meq/100 g.
77
-------
Table 37. Concentration of cadmium in corn stover and grain during
applications of sewage sludge and for three growing seasons
after the final sludge application21 (Webber and Beauchamp,
1979)
Cadmium concentration in plant tissue
Cd addition
Year
Annual Cumulative
Stover
Control13
i it
1
2
3
4
5
6
Kg/ na
7.6 7.6
7.2
4.4
0
0
0
14.8
19.2
19.2
19.2
19.2
0.17
0.18
0.07
0.19
0.20
0.26
Sludge
Grain
Control13
Sludge
S/ *^6
1.49 0.02
1.68
0.98
1.64
2.05
1.36
0.01
0.01
0.05
0.04
0.03
0.07
0.12
0.10
0.10
0.11
0.06
Silt loam soil, pH = 7.6, CEC = 26 meq/100 g.
No Cd was applied to the control plots.
78
-------
Table 38. Concentrations of cadmium and zinc from 1972 through 1979
in plants grown on soil without previous additions of these
metals and with a single application of the metals in sludge
in 1971a (Giordano et al., 1979a)
Metals
applied in
1971
Zn Cd
Vcr/Tia
K.g/ nd
0 0
90 2.5
180 5.0
360 10
Metal concentration
Yearb
Soil
PH
Snapbean
leaves
Zn
Cd
Snapbean
pods
Zn
Cd
in indicated crops
Sweetcorn
Leaves
Zn
Cd
Grain
Zn
Cd
mg/kg
1972
1973
1974
1975
1976
1977
1978
1979
1972
1973
1974
1975
1976
1977
1978
1979
1972
1973
1974
1975
1976
1977
1978
1979
1972
1973
1974
1975
1976
1977
1978
1979
4.
5.
6.
6.
4.
4.
6.
6.
5.
4.
5.
5.
4.
4.
5.
6.
5.
5.
5.
5.
4.
4.
5.
6.
5.
5.
5.
6.
4.
5.
6.
6.
9
6
4
3
2
6
0
4
3
9
2
5
2
5
9
4
3
2
6
7
3
6
9
3
6
4
9
1
4
0
1
6
60
44
53
42
93
124
47
-
158
171
282
128
253
191
68
-
189
184
254
141
356
319
79
-
164
187
296
128
499
408
137
0.5
0.3
0.4
0.2
0.7
1.3
0.3
-
1.1
1.0
1.2
0.8
3.0
2.9
0.4
-
1.2
0.8
1.0.
1.0
4.3
6.3
0.5
-
1.2
0.9
1.1
0.8
4.6
9.1
0.8
45
49
59
53
52
64
48
-
61
72
86
71
66
88
60
-
75
90
91
82
92
77
61
-
83
90'
87
79
92
77
83
0.2
0.1
0.1
0.1
0.3
0.2
0.2
-
0.2
0.2
0.2
0.2
0.5
0.5
0.2
-
0.2
0.2
0.2
0.2
0.7
0.5
0.2
-
0.3
0.2
0.2
0.2
0.8
0.2
0.3
41
47
28
30
72
86
94
63
94
153
98
130
209
126
164
107
95
184
94
158
244
161
204
138
97
207
130
172
234
159
273
137
0.9
1.1
0.6
0.7
1.0
0.9
2.2
1.1
3.7
3.9
2.8
3.4
2.7
1.8
4.8
3.0
3.5
5.4
3.5
4.7
4.1
2.5
5.7
5.2
4.1 .
7.2
4.8
5.9
5.7
1.9
7.8
5.5
37
35
35
36
44
39
30
43
47
48
45
-
54
47
43
49
46
49
48
-
66
48
38
44.
54
63
51
-
65
60
44
0.3
0.3
0.2
0.2
0.6
0.5
0.4
0.9
0.7
0.5
0.8
-
0.7
0.8
0.7
1.0
0.8
0.5
0.9
-
1.2
0.8
0.8
1.2
1.0
0.6
1.0
-
1.2
0.9
1.0
Decatur silt loam, CEC = 10 meq/100 g.
Sulfur was applied in the fall of 1975 and limestone in the fall of 1977.
79
-------
Table 39. Cadmium and zinc found in 1977 in soils and crops of sludge
utilization farms in I northeastern United States (Clianey and
Hornick, 1978 and unpublished data)
Metal concentration in crops
Total content
City and
treatment a
4C
4C-L
4S
4S-L
9C
9C-L
9S
9S-L
13C
13C-L
13S
13S-L
1C
1C-L
IS
1S-L
1S-H
19C-H
19S-H
39C-H
39S-H
in soil
»b Zn
Cd
«,~ /i
mp
73
63
156
154
53
51
82
91
59
61
146
128
53
52
146
212
150
52
156
56
602
=>l *&
0.22
0.16
0.98
0.94
0.18
0.15
1.66
2.10
0.10
0.10
9.10
, 7.02
0.07
0.07
3.26
4.50
2.54
0.09
0.41
0.05
12.7
Soil
5.4
6.4
4.9
6.0
4.9
6.4
4.9
6.3
5.3
6.1
5.5
6.2
5.9
6.3
5.5
6.2
6.6
6.1
5.9
5.6
6.7
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/8- 81-003
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Effect of Sewage Sludge .on the Cadmium and Zinc
Content of Crops
5. REPORT DATE
FEBBUAEY 1981. ISSUING DATE.
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Task Force of 25 Scientists
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
Council for Agricultural Science and Technology
250 Memorial Union
Ames, Iowa 50011
11. CONTRACT/GRANT NO.
SPONSORJNG AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory--Cin.,OH
Office of Research and Development
U. S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Contact: James A. Ryan (513) 684-7653
16. ABSTRACT
This report eyaluates the available data on the effects on plants of single
and repeated additions of Cd and Zn to soils in the form of sewage sludge. The
concentrations of Cd and Zn in plants vary with (a) the species and cultivation
grown, (b) environmental and management factors, (c) soil properties, (d) the
annual and cumulative amounts of Cd and Zn applied to soils and (e) the plant
sampled.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Sludge disposal
Metals
Sewage sludge
Land application
T3B
8. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)'
Unclassified
21. NO. OF PAGES
91
2O. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
81
it U.S. GOVERNMENT PRINTING OFFICE: 1981 -757-064/OZ77
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