United States
Environmental Protection
Agency
Robert S. Kerr Environmental
Research Laboratory
Ada OK 74820
Research and Development
EPA/600/S2-88/036 Aug. 1988
&EPA Project Summary
Factors Affecting Trace Metal
Mobility in Subsurface Soils
J. Kotuby-Amacher and R. P. Gambrell
Laboratory and field investigations
were conducted to study factors
affecting the mobility of metals in
soils.The project focused on
subsoils associated with waste
disposal sites and examined a wide
range of conditions that might be
present influencing movement of
metals.
Field and laboratory work
demonstrated acidic wastes
associated with a battery recycling
operation has combined with the
relatively poor metal retention
properties of the soils in the area to
transport excess lead to the shallow
groundwater zone in a southeastern
Louisiana location. Conversely, field
and laboratory data indicate a soil
with a higher clay content and a near
neutral to slightly alkaline pH can
effectively immobilize high levels of
metals such as now-closed
disposal pits used for metals plating
and other waste at an Oklahoma Air
Force base.
The study showed Important
interactions between soil types,
metals, metal concentrations, and
the presence of additional non-
metallic waste materials (co-
wastes) on the movement of metals
in subsoils. Disregarding any of
these factors when evaluating the
potential for metals leaching at a
contaminated site could result in
large errors in predicting metal
mobility and the potential for
groundwater contamination.
The most significant new
information from this project pertains
to the effects of co-wastes, when
present, on facilitating the movement
of trace and toxic metals in subsoils.
The findings of this project lead to
the recommendation that more
research should be done to: (1)
identify the important characteristics
of various types of co-wastes that
facilitate metal mobility, and (2)
quantify these effects to aid in
development of models predicting
metal mobility in subsoils. The
particular metals present, the
amounts of metals present, and soil
properties must also be considered
as all of these parameters interact in
affecting metal mobility in subsoils.
This Project Summary was devel-
oped by EPA's Robert S. Kerr
Environmental Research Laboratory,
Ada, OK, to announce key findings of
the research pro/ect that Is fully
documented in a separate report of
the same title (see Project Report
ordering information at back).
Introduction
Background
The transport of metals to groundwater
below hazardous waste sites is of
considerable environmental concern. The
movement of a particular metal is
determined by the amount and form of
the metal, the soil's chemical and
physical properties, and the composition
of the soil or waste solution with which
the metal is associated. The soil
properties affecting metal
retention/release and transport include
bulk density, surface area, particle-size
distribution, pH, redox status, ion
exchange capacity, amount of organic
matter, type and amount of metaloxides
present, and type and amount of clay
minerals (Fuller and Warrick, 1985). Soils
with a wide range of these properties
were selected for this study except that
all of the subsoil materials had typically
-------
low levels of organic matter. Soil organic
matter, at levels commonly found in
surface soils and sediments, is one of
the primary immobilizing processes for
trace and toxic metals (Gerritse and van
Driel, 1984; Levi-Minzi et al. 1976).
Subsoils, usually beginning 15 to 30 cm
beneath the surface, generally contain so
little naturally-occurring organic matter
that it becomes important to focus on
other metal retention processes in the
region between surface soils and
groundwater.
The greater the concentration of a
specific pollutant in the soil, the more
likely it is to move through the soil. When
the concentration of a metal exceeds the
capacity of the soil to retain it, migration
may take place as if the soil were an
inert, porous medium (Fuller, 1980).
Solution composition will also greatly
affect metal retention and movement.
Doner (1978) reported that the mobility of
Ni, Cu, and Cd through soil columns was
1.1 to 4 times greater in CI" solutions
than in CICV solutions, with the greater
effect seen for Cd. Perchlorate was
reported to not complex metals. In most
of the cases studied by Benjamin and
Leckie (1982), addition of Cf or SO42'
reduced Cd retention indicating that
chloro- and sulfato- complexes are
retained less strongly by the soil than are
uncomplexed Cd ions. Garcia-Miragaya
and Page (1976) found that Cd retention
decreased in the order (same ionic
strength): CI4" > SCU2" >CI~. Brown
(1979) stated that the formation of
complexes of Pb with various anions
such as CI", F, CO32', HC03', and
OH" increased the concentration of Pb
in natural waters by preventing Pb from
taking part in other chemical reactions,
primarily adsorption, which would lower
the solution concentration.
Knox and Jones (1979) reported that
all of three sanitary landfill leachates they
tested were able to complex Cd to some
extent, although their ability to do so
varied, and in some cases might well
have been insufficient to greatly affect
metal retention. The reaction between Cd
and leachate appeared to be mono-
nuclear and predominately the result of a
1:1 complex formation. Although fatty
acids were the most important com-
plex-forming fraction in one leachate
studied, other organic compounds, such
as fulvic acid, were important in the other
two leachates. Thus, the degree of metal
immobilization or transport depends
upon interaction between soil properties,
amount of metals present, and the
properties of the leachate phase with
which the metals are associated.
An aerobic environment increases the
solubility and mobility of metals (Fuller,
1980; Bates, 1980), or decreases the
solubility of metals (Page and Pratt,
1975), depending on the absence or
presence of sulfides and other redox-
active components in the system
(Gambrell, et al. 1980; Khalid et al.,
1981). The adsorption and
coprecipitation of trace and toxicmetals
with colloidal hydrous oxides is an
important process in decreasing metal
availability in some soils. The oxides and
hydroxides are favored by an increase in
pH and/or redox potential. When hydrous
Fe and Mn oxides are reduced, the trace
and toxic metals which are coprecipitated
with or retained by the oxides may be
released (Thibodeaux, I979). The
formation of insoluble metal sulfide
precipitates limits the bioavailability of
most metals in some strongly reduced
soils and sediments. In general, where
sulfides are not present, as in most
subsoils, a moderately low pH and redox
potential environment favors the
relatively bioavailable soluble and
exchangeable chemical forms of metals
while higher pH and oxidation levels
favor sparingly soluble, oxidized
compounds. Cadmium, however, has
been found to show the opposite redox
effects in sediments (Gambrell, et al.
I976). In surface soils and sediments,
oxidizing, weakly acid conditions greatly
increases levels of soluble and weakly
acid conditions greatly increases levels
of soluble and exchangeable Cd.
There are a number of reviews and
reports on factors affecting the mobility
and plant availability of trace and toxic
metals. Much of this work has focused
on topsoils or sediments containing an
appreciable amount of naturally occurring
organic matter compared to subsoils.
Soil humic material is known to be very
effective in immobilizing most trace and
toxic metals. Since subsoils contain
much less organic matter and are the
primary transport media if metals
contamination of groundwater is to occur,
research efforts should be directed
toward processes regulating metal
mobility in subsoils.
The objectives of this project were as
follows:
(1) To identify soil physical and
chemical properties regulating the
mobility of metals in subsurface soil
materials. This research focused on
subsoils between the contaminated soil
at or near the surface and the
groundwater. Much has been published
on the mobility and biological availability
of metals in surface soils and sedimenl
Factors affecting the mobility of meta
from waste disposal sites in subsoils hi
received comparatively little attention.
(2) To show for a number of kt
metals the important interaction
between metal concentrations, wasi
mixtures, and soil properties in reg(
lating the mobility of metals. It is w<
documented that all metals do m
respond identically to mobilizatioi
immobilization processes in soil.
addition to soil properties and th
particular metals present, there are tv\
other important factors that may influent
the mobility of metals in subsoils: (1) th
concentrations of metals present, and (i
the presence of other types of waste
that may influence the mobility of metal
These two factors have particule
relevance to waste sites presenting
threat to groundwater and wer
considered in planning this study. Th
interaction between the four factor
mentioned above were studied in th
context of hazardous waste disposal site
which represent the greatest potentii
threat to groundwater contamination b
metals.
In a hazardous waste dump or landfil
a variety of types of waste may b
present that become mixed with metal
at or beneath the site. Mixtures of metal
and other wastes may interact t
influence the mobilization of metals. Th
presence of toxic metals with acidi
wastes, for example, would greatl
enhance the leaching of metals beneat
the initial disposal zone towar
groundwater. This is a set o
circumstances that has not bee
thoroughly addressed in the toxic metal
studies associated with sludge
amended soils or dredged materials a
very acidic conditions are very rarel
encountered in these situations. Alsc
certain organic wastes in higl
concentration may affect the mobility c
metals. It is likely there are man'
locations where waste mixtures an
present that may enhance or havi
already enhanced the leaching of metal
to groundwater. The concept of facilitate!
transport of metals in waste mixtures ha;
not yet received the research attention i
deserves. This project was designed t<
begin to examine this topic.
The greatest potential threat fo
groundwater contamination by toxn
metals comes from the many illegal
poorly planned, and/or poorly managei
hazardous waste disposal sites in thi
country. Many of these were establishet
-------
and used prior to the knowledge we now
have on groundwater contamination and
the better regulatory restrictions of recent
years. It is not unreasonable to expect a
combination of coarse-textured sub-
surface soils, high concentrations of
metals, and the presence of co-wastes
that tend to mobilize metals at a
substantial number of these sites.
Procedure
Field and laboratory studies were
conducted to examine factors affecting
the mobility of metals in subsoils. The
experimental approaches for these
studies are summarized below.
Field Studies
The objectives of the field studies were
to determine the distribution of forms of
trace and toxic metal contaminants in the
subsoil at sites with known or suspected
potential for groundwater contamination.
Soil cores were taken to a depth
generally between 2 and 3 meters at the
sites with a hydraulically-driven 4.75-
cm stainless steel coring tube. The plan
was to obtain duplicate cores within the
disposal zone and two additional pairs of
cores over increasing distances from the
disposal ozone where possible. The
cores were sectioned with depth in the
field, stored in plastic bottles, and then
returned to the lab for analysis.
The field studies were planned to be
coordinated with laboratory studies in
terms of the soil materials and the
contaminants present. Assistance in
locating and accessing contaminated
field sites was obtained from the USEPA,
U.S. Air Force, the Louisiana Department
of Environmental Quality (DEQ), and the
Louisiana Department of Transportation
and Development (DOTD). We were
seeking five sites with known metal
contamination problems.
Though considerable effort was
expended in identifying the sites,
securing authorization for access to the
sites, sampling, and analyzing samples,
this effort was only partially successful
because clear indication of high metals
contamination was not apparent in core
samples from several of the locations.
Two of the most promising sites in
Louisiana were unavailable at the last
minute, and alternative sites were
selected.
Laboratory Studies
Three laboratory studies were
conducted to examine factors affecting
metals movement in subsoils. These
included batch and column transport
studies. The first batch study focused on
retention of a number of metals (Cd, Ni,
Pb, and Zn) in many soil types with and
without the presence of a simulated co-
waste. The term co-waste refers to a
non-metallic waste material that may be
present at a disposal site, possibly
facilitating the mobility of metals.
Calculations of adsorption coefficients
and regression analyses were used to
examine the effects of specific soil
properties and the presence of a
leechate on metal retention. Because of
the importance of soil redox potential on
the environmental chemistry of metals, a
second batch study was done with Cd
and Pb and various co-wastes in fewer
soil materials, but under different purge
gases simulating aerobic and anoxic
conditions in the subsoil materials. The
column transport study included two soil
materials receiving two levels each of Pb
and Cd associated with four leaching
solutions.
Results and Discussion
Field Studies
Of the field sites studied, a lead-acid
battery reprocessing location yielded the
most information in terms of metals
contamination which has apparently
moved to shallow groundwater. A waste
disposal pit for metals and other
materials at another Air Force base may
have also contributed to shallow
groundwater contamination by metals.
The data collected at an arsenic dipping
vat, a metal waste disposal pit at another
Air Force base in OK, and an oil
reprocessing site in Louisiana did not
indicate significant metals transport was
occurring in the subsoils associated with
these sites.
A brief summary of the results from
the field study sites is given below.
Kolin Arsenic Dipping Vat
It is acknowledged that As (arsenic) is
not a metal. But, for simplicity in this
report where the focus of the project is
mentioned, the terms trace metals and
toxic metals are used and intended to
include As.
This was the site of a concrete-lined
dipping vat used to treat livestock to
remove parasites. A shallow groundwater
sample taken from very near the pit
contained about 0.3 mg/l As or, for
comparison purposes, this was about six
times USEPA drinking water quality
criteria. Levels exceeding 500 jig/g total
As in the soil were found to a depth of
about 0.5 meters in cores taken from
very near the vat. Five of six samples
above the 0.5 meter depth contained 180
ng/g As or higher. However, beneath 1.5
meters, levels dropped to near
background. The high total levels near
the surface supported elevated levels of
water and acid-extractable As. These
forms dropped to near background levels
beneath about 1.5 meters.
Maximum As levels in the shallow
subsoil vs. deeper subsoil suggested that
most of the As associated with the pit
may be retained strongly by the soil at
this site such that leaching beneath at
least a couple of meters may have been
negligible. However, it should be
acknowledged that the history of use of
this cattle-dipping vat is not known and
the first sampling occurred about three
decades after its use was discontinued.
The possibility of transformations
between different species of As with
different mobilities and the presence of a
crack in the concrete liner of the pit
complicated evaluating the data obtained
at this site. Therefore, it is possible that
considerable As may have been
transported from the site during the
intervening years for which there is no
current evidence.
Combustion, Inc.
Combustion Inc. is a site where waste
oil was stored in pits for later
reprocessing. The now-closed facility is
a Superfund site. Cores taken to 2
meters depth at the edge of an oil pond
particularly recommended to us by DEQ
personnel, as well as additional cores
taken in the area, did not indicate
elevated metal concentrations over levels
typically found in uncontaminated soils.
At this time, we do not know if additional
exhaustive sampling would have
indicated very localized areas of metal
contamination at the site, or whether DEQ
was basing their belief of metals
contamination at this site on unreliable
information.
Tinker Air Force Base, Waste
Pit #2 and Waste Pit #1
According to Air Force personnel and
maps provided us, our Waste Pit #2, "A"
core samples were collected within the
old waste disposal pit (now covered and
not discernible from the surrounding
landscape). Neither these samples nor
two additional pairs of core samples
taken downslope from the disposal pits
showed concentrations of any metals
measured above typical soil background
levels.
At this site, reliable information is
available that high levels of metals are
-------
associated with the site. This information
comes from personnel familiar with the
operations of the site years ago and
much more recent metal survey work
done at the site. Though a geologist
working with us believed we were in the
pit based on examining the core material
collected, we can only surmise now that
our cores missed the actual disposal pit,
possibly penetrating an adjacent zone
disturbed for some other purpose.
Nevertheless, the lack of metals from
deep cores obviously very close to the
actual pit and additional downslope cores
indicates the subsurface soil at this site
does very effectively immobilize high
concentrations of metals. The laboratory
work with control soil from the site
confirms this conclusion. Similarity, high
concentrations of metals were not found
at another waste disposal site sampled at
Tinker Air Force Base.
Robins Air Force Base
As for Tinker Air Force Base, maps
and information from personnel familiar
with the former waste disposal operations
at this base were made available to us.
Though covered with soil when disposal
operations ceased, visual confirmation of
the disposal pits was possible at this site.
Beneath the cap or cover soil placed
on the pits, the core samples were
saturated with a black, oily liquid from
organic wastes also dumped at the site.
This necessitated special precautions
working with this possible hazardous,
volatile organic waste, and complicated
sample processing using conventional
methods of characterizing the form of
metals present in soil materials. Thus, a
complete chemical characterization of
the site was not completed in time for
this report.
Many samples from several cores at
this site were highly contaminated with
Cd, Cr, Cu, Ni, Pb, and Zn. In addition,
cores from an adjacent area between the
disposal pits and the surrounding swamp
were also saturated with the same oily
liquid as the pit samples, and also
contained some of the highest levels of
metals. Clearly, this is a site with a high
potential for metals movement through
subsoils, possibly facilitated by high
levels of organic waste present. If
information that our Core E samples
were taken away from the disposal area
is correct, then the data indicate
substantial movement of several metals
has occurred in the shallow groundwater.
Pontchatoula Battery
The study site at Pontchatoula Battery
was the former location of a pile of old
automobile and marine batteries awaiting
reprocessing to reclaim the Pb. The pile
was reported to be 100 meters X 30
meters X 10 meters high at one time.
The battery cases were not stacked
upright and apparently cracked in many
cases such that substantial quantities of
concentrated sulfuric acid containing Pb
spilled from the pile onto the soil.
Surface soil samples contained several
thousand ng/g Pb and another zone of
excess Pb concentrations was found at
the surface of the shallow groundwater
just over a meter beneath the surface.
Elevated Pb in the shallow groundwater
zone at a depth of over 2 meters in what
was believed to be a control area
(several hundred meters away from the
battery storage site) suggested Pb
transport in groundwater may be
occurring at this location.
This is an example of a worst case
situation for metals mobility. The surface
and subsurface soil at the site is coarse
textured containing relatively low levels
of clay and hydrous iron oxides that
would normally be effective in
immobilizing Pb. An important additional
circumstance is the presence of large
quantities of spilled, strong acid which
acidified the soil to the shallow
groundwater. This apparently facilitated
transport of this metal through the soil.
Laboratory Studies
Most work with metal mobility and
bioavailability has been done with
surface soils containing an appreciable
organic matter content compared to
subsurface soils which are the transport
media for metals between waste disposal
sites and groundwater. Data were
presented illustrating the difference
between surface and subsurface soils on
metal retention capacity. More
importantly, and pertaining to the focus
of this project, the laboratory studies
clearly demonstrated that subsoils
differing in physical and chemical
properties will show substantial
differences in their ability to immobilize
trace and toxic metals. Sandy soils and
weakly acid soils are much less effective
in retaining metals than soils near neutral
to alkaline in pH and containing high
levels of clay.
The amount of metals present in the
soil was shown to be an important factor
in determining mobility. At higher
concentrations that may be associated
with waste disposal sites, many soils
become less effective in immobilizing
metals. Apparently, the immobilization
processes in soils are overwhelmed.
However, as indicated in the previo
paragraph, some soils showed the abil
to effectively immobilize very hii
concentrations of metals.
Though this project focused on subs
materials, the preceding two paragrap
summarize findings that one mig
expect based on previous work w
surface soils. The paragraph bel<
briefly introduces a significant, relative
new research topic.
A subject that has received minirr
research attention related to met«
mobility in soils is facilitated transport
other waste materials that may I
present. The likely role of facilitati
transport was evident at two of the fie
sites studied. Both batch equilibratii
and column leaching studi<
demonstrated the presence of oth
waste materials in addition to metals
concern can significantly enham
mobility of metals. The presence ai
effects of such co-wastes are importa
factors that have been overlooked ti
often in the past when evaluating tl
potential for metals movement ar
groundwater contamination. The c
wastes studied included a synthel
municipal leachate, a simulated acid
metals waste, and a synthetic oil fie
waste. Column leaching studies cleai
demonstrated complex formatic
between both Cd and Pb with differe
components of the synthetic municip
landfill leachate since two distm
concentration peaks occurred with time
column eluents.
Another topic that has received litl
research attention is the influence
subsoil redox potential conditions (
metal mobility. One of the project's bat<
equilibrium retention studies included th
parameter. Under the conditions of tr>
study, the data suggested soil oxidatk
status may have some influence on met
retention, but the effect was less than tl
other variables studied in this proje
(different metals, metal concentration
soils, and co-wastes present).
Conclusions and
Recommendations
Field Studies
Kolin As Dipping Vat
Our data suggested that As associate
with this old cattle dipping vat may I
strongly retained by the surroundir
subsoil such that leaching beneath
couple of meters has been negligibl
However, definite conclusions at this si
are not possible because a chemic
-------
history of the site is not available (the vat
was last used decades prior to any
sampling at the site) and because
transformations between several species
of As with different mobilities may have
occurred complicating determination of
what may have happened over the years.
Also, a crack in the concrete walls of the
below-ground vat may have released
As directly into the subsoil zones where
samples were obtained making an
evaluation of the data difficult. There was
some indication that iron oxides in the
subsoils tended to retain the As.
Combustion Inc.
Contrary to the information provided
us, metals wastes do not appear to be a
problem at this site based on our limited
sampling.
Pontchatoula Battery
Lead, usually one of the least mobile of
the common toxic elements in soils, had
moved vertically to shallow groundwater
at a former battery recycling plant.
Subsequent lateral movement in the
groundwater is also indicated. At this
site, Pb movement was facilitated by the
combined presence of sandy subsoils
and a co-waste consisting of large
quantities of spilled sulfuric acid.
Tinker AFB
Field sampling indicated metals were
not moving appreciably in subsoils from
closed waste disposal pits examined at
Tinker Air Force Base. Soil properties at
this site apparently result in effective
immobilization. Laboratory studies with
this soil supported the conclusions that
metals are strongly retained in the soil at
this site relative to other sites and soil
materials examined.
Robins AFB
Assuming disposal zone boundaries
were correctly delineated on maps
provided us, high concentrations of
several metals have moved laterally in
shallow groundwater from a closed
disposal site toward an adjacent swampy
area. High levels of organic wastes may
have facilitated metals movement at this
site.
Laboratory Studies
The laboratory studies demonstrated:
1. Subsoils are generally less effective in
immobilizing metals compared to
1 surface soils and sediments.
2. The metal-immobilizing capacity of
subsoils increases with pH, clay
content, cation exchange capacity, and
hydrous oxide content of the subsoil.
Several of these factors are related in
soils such that in general, sandy soils
offer a high potential for metal mobility
compared to finer textured soils.
3. Metals tend to be more mobile in soils
as their concentration increases. This
is likely due to high levels exceeding
the capacity of various immobilizing
processes.
4. One of the important aspects of this
study was the demonstration that the
presence of co-wastes containing
complexing anions, competing cations,
or high acid contents tend to facilitate
metal movement in soil. In particular, a
synthetic municipal landfill leachate
studied resulted in substantially less
retention of metals by most of the soil
materials studied.
5. Results of short-term laboratory
studies suggested oxidized subsoils
tend to be more effective in
immobilizing metals than anoxic
subsoils, but the differences found in
this preliminary study were relatively
small.
6.There are important interactions
affecting metal mobility between: (1)
the kinds of metals present, (2) the
amounts of metals present, (3) soil
properties, and (4) the presence of
co-wastes. For example, whether or
not the presence of a particular co-
waste will have no effect, a moderate
effect, or a very large effect on the
mobility of metals can depend on the
properties of the soil material.
Complimentary Findings of
Field and Laboratory Studies
Though a quantitative relationship
between field and lab results was not
attempted, the laboratory data supported
the findings of the field studies. Using
the same or very similar subsoil
materials, the lab studies demonstrated
the effective metal immobilizing
characteristics of the subsoil at the
Tinker AFB site where field sampling
indicated metal movement is apparently
not a problem.
In contrast, lab studies demonstrated
coarse-textured subsoils permitted
leaching of Pb, normally considered a
relatively immobile toxic metal. The
additional presence of other simulated
wastes substantially facilitated release
and transport of Pb and other metals.This
helped explain shallow groundwater
contamination by Pb at an old battery
recycling plant and the apparent
movement of Pb and other metals at
another Air Force base disposal site.
A major finding of this work
representing a relatively new research
topic was the demonstration that several
types of non-metallic wastes can greatly
facilitate the movement of metals in
subsoils.
Recommendations
The findings of this project lead to the
recommendation that the presence of
waste materials other than metals at
disposal sites must be considered in
evaluating the potential for metals
contamination of groundwater. Additional
research should be done on: (1)
identifying the important components of
various types of co-waste that facilitate
metal mobility in soils, and, (2)
quantifying these effects to aid in model
development. Also, the interaction
between subsoil properties, kinds and
amounts of metals present, and kinds
and amounts of co-wastes present
should receive more research attention in
order to develop models that will
adequately predict metals movement
under the range of conditions associated
with waste disposal sites.
Literature Cited
Bates, M. H. 1980. Fate and transport of
heavy metals. Presented at Seminar
on Ground Water Quality, Oklahoma
Center for Continuing Education,
University of Oklahoma,, Norman,
Oklahoma, 24 July, 1980.
Benjamin, M. M., and J. O. Leckie. 1982.
Effects of complexation by Cl, 564,
and 8303 on adsorption behavior of
Cd on oxide surfaces. Environ. Sci.
and Technol. 16:162-170.
Brown, D. W. 1979. Adsorption of lead
from solution on the quartz- and
feldspar-containing silt fraction of a
natural streambed sediment. In: E.A.
Jenne (ed.) Chemical Modelling in
Aqueous Systems, ACS Symposium
Series 93. American Chemical
Society. Washington, D.C. (pp. 237-
260).
Doner, H. E. 1978. Chloride as a factor in
mobilities of Ni(ll), Cu(ll), and Cd(ll) in
-------
soil. Soil Sci. Soc. Am. J. 42:882-
885.
Fuller, W. H. 1980. Soil modification to
minimize movement of pollutants from
solid waste operations. CRC Grit. Rev.
in Environ. Control 9(3):213-269.
Fuller, W. H., and A. W. Warrick. 1985.
Soils in Waste Treatment and
Utilization: Volume 1, Land Treatment;
Volume II, Pollutant Containment,
Monitoring, and Closure. CRC Press,
Inc., Boca Raton, Florida, (268 and
235 p.).
Gambrell, R. P., R. A. Khalid, V .R. Col-
lard, C. N. Reddy, and W. H. Patrick,
Jr. 1976. The effect of pH and redox
potential on heavy metal chemistry in
sediment-water systems affecting
toxic metal bioavailability. In:
Dredging: Environmental Effects and
Technology Proceedings of WODCON
VII San Francisco, California, 10-12
July, 1976 (pp. 581-600).
Gambrell, R. P., R. A. Khalid, and W. H.
Patrick, Jr. 1980. Chemical availability
of mercury, lead, and zinc in Mobile
Bay sediment suspensions as affected
by pH and oxidation-reduction
conditions. Environ. Sci. Technol.
14:431-436.
Garcia-Miragaya, J., and A. L. Page.
1976. Influence of ionic strength and
inorganic complex formation on the
sorption of trace amounts of Cd by
montmorillonite. Soil Sci. Soc. Am J.
40:658-663.
Gerritse, R. G., and W. van Driel. 1984.
The relationship between adsorption
of trace metals, organic matter, and
pH in temperate soils. J. Environ.
Qual. 13:197-204.
Khalid, R. A., R. P. Gambrell, and W. H.
Patrick, Jr. 1981. Chemical availability
of cadmium in Mississippi River
sediment. J. Environ. Qual. 10:523-
528.
Knox, K., and P. H. Jones. 1979. Com-
plexation of heavy metals in sanitary
landfill leachates. In: Proceedings
International Conference on
Management and Control of Heavy
Metals in the Environment, London,
September, 1979 (pp. 244-248).
Levi-Minzi, R., G. F. Soldatiri, and R.
Riffaldi. 1976. Cadmium adsorption by
soils. J. Soil Sci. 27:10-15.
Page, A. L., and P. F. Pratt. 1975. Effects
of sewage sludge or effluent
application to soil on the movement of
nitrogen, phosphorus, soluble salts,
and trace elements to groundwater. In:
Proceedings of the 1975 National
Conference on Municipal Sludge
Management and Disposal, (pp. 179-
187)
Thibodeaux, L. J. 1979. Chemo-
dynamics, John Wiley and Sons, New
York (501 p.).
-------
L. Kotuby-Amacher and R. P. Gambrell are with the Center for Wetland
Resources, Louisiana State University, Baton Rouge, LA 70803-7511.
Bert E. Bledsoe is the EPA Project Officer (see below).
The complete report, entitled "Factors Affecting Trace Metal Mobility in
Subsurface Soils," (Order No. PB 88-224 8291AS; Cost: $19.95, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Robert S. Kerr Environmental Research Laboratory
U.S. Environmental Protection Agency
P.O. Box 1198
Ada, OK 74820
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/600/S2-88/036
0000329 PS
U S gNVIR PROTfCTION AGIMCY
REGION 5 LIBRARY
330 S DEARBORN STREET
CHICAGO IL 6060*
------- |