Table II

Heavy metal content of vegetation and spill samples from
the vicinity of the Tacoma Smelter. (Concentrations expressed
in parts-per-million on a dry weight basis)

Sample No. Location Sample Arsenic Cadmium Lead Mercury
7544016 5621 N. 46th St. soil 214 2.9 238 11.0
7544034 cabbage 11.4 2.9 9 0.5
7544017 969 Altadena Dr. soil 12.2 1.0 9 0.2
7544035 cabbage 1.5 2.7 16 0.7
7544018 1719 Naomi P1. soil 7.3 1.8 271 0.2
(Seattle)
7544036 cabbage 1.8 1.8 12 0.3
7544037 5141 N. Ruby St. soil 457 8.3 743 6.8
7544038 lettuce 110 2.3 28 1.0
_ (unwashed)
7544039 lettuce 68.5 3.1 7 1.2
(washed)
7545004 Manzanita Beach soil 36.2 1.6 305 0.6
Muary Island
7545001 broccolli 12.5 0.8 am 0.5
7545005 Piner Point, soil 36.8 1.4 70 0.2
Muary Island
7545002 cabbage 3.1 0.6 9 0.2
7545006 Neill Point soil 39.1 1.8 68 0.3
Vashom Island
7545003 broccolli 10.9 3.35 19 0.6
7547001 5130 N. 48th St. cabbage 1.6 0.9 8 0.1
(inner head)
7547002 brussel sprouts 30.8 0.8 7 0.1
7547003 5129 N. 47th St. saurkraut 0.6 1.1 5 0.06
7547004 5140 N. 47th St. cabbage 1.2 0.8 v 0.1

(inner head)

14


as

amounts of volatilized mercury are known to be toxic to roses in
greenhouses.

The mercury concentrations in the samples from Tacoma are well
above the "normal" mercury content. The values are on the threshold of
being a serious environmental hazard.


Fig. 2a

Mercury concentration (ppm) in vegetation
in the Tacoma area.

COMMENCEMENT
0.5 BAY

ro

0.3,,2

b5 204
ON.

—0.4
0.5— —0.7
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&
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——
\ 0 1 12
[ ee
Scale of miles
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° TACOMA

Pe

18



CONTENTS

Abstract

List of Figures

Sections

I Background

II Sampling and Site Evaluation

III Effects

IV Results

v Control Measures

VI Conclusions

VII Toxicity and Biogeochemistry
of Elements

VIII Tables of Heavy Metal Content

iii

10
11

12
13


Table III

Heavy metal content of vegetation and soil samples from
the vicinity of the Tacoma Smelter. (Concentrations
expressed in parts-per-million on a dry weight basis)

Sample No Location Sample Arsenic Cadmium Lead Mercury
7542001 5129 N. 47th St. lettuce 657 1200 6.0
(unwashed)
7542002 lettuce 445 700 3.2
(washed)
7542003 cabbage 94 50 0.4
(unwashed)
7542004 cabbage 67 45 0.1
(washed)
7542005 soil 384 1100 3.9
7544001 5110 N. 40th St. soil 44.2 1.86 115 1.37
7544019 brussel sprouts 7.8 2.3 14 0.5
7544002 5618 N. 43rd St. soil 331 iW 972 6.1
7544020 swiss chard 27.6 5.6 19 0.4
7544003 2844 N. Bristol St. soil 24.0 1.5 44 1.5
7544021 cabbage 5.2 8.2 20 0.5
7544004 643 Skyline Dr. soil 26.4 1.4 12 0.7
7544022 brussel sprouts 4.6 5.3 25 0.3
7544005 4845 S. 7th St. soil 16.5 1.5 97 0.2
7544023 cabbage 1.0 3.0 14 0.3
7544006 3106 N. Huson St. soil 55.7 2.3 120 0.6
7544024 cauliflower 5.5 2.6 23 0.7
7544007 2136 N. Mildred St. soil 93.3 2.5 102 0.5
7544025 cabbage 8.5 7.9 W 2.4
7544008 5011 N. 25th St. soil 24.6 0.9 30 1.0
7544026 cabbage 8.7 5.3 20 0.6
7544009 4508 N. Visscher St soil 355 12.0 1190 3.6
7544027 cabbage 14.5 2.4 22 0.8
7544010 8002 W. 31st St. soil 29.7 1.7 52 0.3
7544028 cauliflower 5.2 2.4 21 0.5
7544011 5130 N. 48th St. soil 110 1.8 88 0.9
7544029 brussel sprouts 16.3 1.2 11 0.4
7544012 5140 N. 47th St. soil 326 5.4 505 4.8
7544030 cabbage 32.9 5.0 16 0.3
7544013 5423 N. 49th St. soil 240 8.3 291 1.9
7544031 cabbage 79.2 6.6 9 0.7
7544040 cabbage 128 7.8 65 1.2
(unwashed)
7544014 5447 N. 49th St. soil 247 7.0 819 3.0
7544032 cabbage 3.45 1.5 14 0.3
7544015 3103 N. Winnifred soil 307 7.8 1240 3.6
t.
7544033 cauliflower 35.8 3.5 13 0.5

15


Fig. 3b

Lead concentration (ppm) in garden soils
in the Tacoma area.

COMMENCEMENT
0
aw
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— 11]
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) 1 Wwe
[_ Serres |
Scale of miles

52— a et
TACOMA

ae

21



Fig. 1b

Arsenic concentration (ppm) in garden
soils in the Tacoma area.

COMMENCEMENT
301 BAY

29.7—

0 1 We
[ a e Se |
Scale of miles

TACOMA

Pe

7



Very Toxic:

Moderately Toxic:

Scarcely Toxic:

Arsenic

Cadmium

Copper

Mercury

Lead

Zinc

Sulfur

1/_ 4H. J. M. Bowen, Trace Elements in Biochemistry.

(1966)

2/ 4H. P. Chapman (Ed.) Diagnotic Criteria for Plants and Soils

II,

General Classification of Toxicity of Elements to Plants /1

Toxic effects may be seen at concentrations below 1 ppm

in nutrient solution (included are Cut++, Hg++, Pb++)

Toxic effects appear at concentrations between 7 and 100

ppm in nutrient solution (included are AsIII, AsV, Cd++

Zn++)

Toxic effects rarely appear (included are CI-, I-, Catt

K+)

The Biogeochemistry of the Elements

(Bowen)/1 (Chapman) /2
soils - 6 ppm 0.3-38 ppm 30%
plants - 0.2 ppm 50%
moderately toxic to plants 20%

soils - .06 ppm
plants - 0.2 ppm
moderately toxic to all organisms

soils - 20 (2-100) ppm 10-200 ppm
plants - 14 ppm 5-20 ppm
very toxic to algae, fungi, seed

plants

soils - .03-0.8 ppm
plants - .015 ppm
very toxic to fungi and green plants

soils - 10 ppm 2-200 ppm
plants - 100 ppm 25-150 ppm
very toxic to most plants

soils - 50 ppm 10-300 ppm
plants - 100 ppm 25-150 ppm

moderately toxic to most plants

plants - 3400 ppm 1300-6500 ppm

of California, Div. of Agricultural Sciences (1966)

12

5 ppm or less
5-10 ppm
10 ppm or more

Academic Press, London

University


The absence of legumes in the smelter vicinity may be related to the
levels of copper and other metals in the soil.

B. Zinc

Total zinc in normal soils varies from 10-300 ppm and a wide range
of plants have concentrations of from 20-10,200 ppm. In a variety of
plants normal levels of zinc range from 25-150 ppm and amounts greater
than 400 ppm may indicate toxic levels of zinc.

The levels of zinc present in grass and leaves from the Tacoma
smelter appear to be within the high range of normal and probably are
not directly affecting plants, but may be important indirectly due to
interactions and competition with other heavy metals.

C. Cadmium

Cadmium is present in many soils and is apparently taken up with
ease by a great number of plant species, especially the grasses and
grains; for example, wheat, corn, rice, oats and millet. Cadmium is
also found in peas, beets, lettuce and radishes. The composition of an
"average" plant leaf is 0.5 - 0.6 ppm for cadmium and normal soils contain
ppm cadmium.

Cadmium is toxic to plants at higher concentrations. In radishes
grown in nutrient solutions at concentrations of 100 ppb cadmium, growth
of both roots and tops was reduced. At this level, the concentration
of cadmium in roots and leaves was 16.2 and 81.2 ppm respectively, but
no visible injury was evident.

In Japan, near a zinc refinery, the accumulation of cadmium was
extremely high in leaves of plants. Leafy vegetables such as greens,
cabbages, the leaves of eggplants, green onions and the leaves of radishes

4

06




Background

The Ruston copper smelter in Tacoma, Washington, has been a signifi-
cant source of air pollution during much of its 84 year history. The
emissions consist of S05, S03, acid mist and particulates of arsenic,
lead, zinc, cadmium, copper and sulfates. In 1970, the smelter was
discharging about a ton of particulate matter into the air each day,
containing as much as 590 Ibs. of lead and 876 Ibs. of arsenic. The
sulfur emissions amount to 200,000 tons per year.

There are two specific sources of emissions; (1) S055 and partic-
ulates at a low level around the anode furnaces and plant operations,
and (2) S0,, S03, acid mist and particulates from a tall stack (560
ft.). At present the smelter is functioning under intermittant controls
in which plant operations are shut down when S05 levels are expected to
exceed SO, air quality standards. During 1973, the plant reduced its
operations 25-30 percent.

Winds in the summer are from the north and northwest and carry
emissions from the smelter to residential and open areas in west Tacoma,
while during much of the fall, winter, and early spring the winds are
from the south and southwest and carry effluent to offshore islands
(Vashon and Muary Islands) in Puget Sound.

Sampling and Site Evaluation

In response to a request from EPA, Region X for assistance in
estimating the terrestrial impact of the smelter on the immediate area,
visits were made to the Tacoma smelter area to collect soil and vegetation


FIGURES.

No. Page
la Arsenic Concentration in Vegetation 16
1b Arsenic Concentration in Garden Soils 17
2a Mercury Concentration in Vegetation 18
2b Mercury Concentration in Garden Soils 19
3a Lead Concentration in Vegetation 20
3b Lead Concentration in Garden Soils 21
4a Cadmium Concentration in Vegetation 22
4b Cadmium Concentration in Garden Soils 23

iv


Heavy metal content of vegetation and soil samples from
the vicinity of the Tacoma Smelter.
expressed in parts-per-million on a dry weight basis)

TABLE I

(Concentrations

Sample No. Location Sample Arsenic Cadmium Lead Mercury Zinc Copper Antimony Sulfur
7516001 5020 Lexington St. grass 168 5 160 2 381 608 229 8090
7516002 6102 Park Avenue grass 56. 4 51 2 49 350 148 9960
7516003 5309 Ruby Street grass 396 8 450 8 208 2260 244 21900
7516004 4852 N. 50th St. grass 797 12 470 8 288 3040 165 13600
7516005 5311 Commercial Ave. grass 472 16 692 10 190 3150 332 8000
7532001 Court & Baltimore grass 582 4 250 3.0 113 1400 - -
7532002 Court & Baltimore maple leaves 167 2 50 1.3 113 1400 - -
7532003 5621 N. 46th St. pear 9 2 10 0.3 49 54 - -
7532004 " horsebean pod 7 2 10 0.4 12 230 - -
7532005 " harsgkean 142 4 55 2.5 180 575 - -

»

7532006 " grape leaves 116 2 49 1.8 50 660 - -
7532007 " squash leaves 66 2 19 1.9 140 303 - -
7532008 " fig leaves 200 2 49 1.3 48 680 - -



peach leaves followed by "shot hole," and then defoliation is indicative
of arsenic injury. Acid mist injures leaves by burning small holes in
the leaf tissue.

In general, plants reflect the geochemical environment in which
they grow. However, mineral elements differ in their availability to
plants and plant species differ in their ability to absorb specific
elements. Many factors determine the availability of a given element to
plants for example, relative abundance, form in which the element is
present, soil pH, interaction of elements, physical condition of the
soil, environmental factors of temperature and soil moisture and genetic
variability. Absorption of toxic metals through the leaf cuticle is a
significant source of contaminating in many species of plants.

Effects
A. Copper

The copper content of normal soils range from 1-200 ppm with most
in the range of 25-60 ppm. Normal plants contain from 5-20 ppm copper.
Copper has long been known to be toxic to plants. Levels in tissues
greater than 20 ppm, in general, are indicative of copper excess.

Excess copper commonly causes reduced growth and iron chlorosis symptoms
in plants and is associated with stunting, reduced branching, thickening
and abnormally dark coloration of rootlets of many plants. Clover,
alfalfa, poppy, spinach, gladious, corn, bean and squash are known to be
sensitive to copper.

The extremely high copper concentrations in grass and other leaf
sample from the smelter vicinity represent a possible environmental
hazard especially to sensitive plant species. These canot become
established and moderately sensitive species will show reduced growth.

3


Fig, 2b

Mercury concentration (ppm) in garden
soils in the Tacoma area.

COMMENCEMENT
3.6 BAY
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bob
LO x4 8

6.1
15/7
© Lo. —0.6

= 0.
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>
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=12
[———__
\ 9 | ie
Scale of miles
03—

TACOMA

Pe

19



660/3-74-012

Ecological Research Series



Some plants showed retarded growth at 10 ppm lead in solution
culture studies. Lead reduced the growth of corn in nutrient solutions
and is translocated and accumulated in high concentrations in the leaves.
Foliar accumulation of lead was 3-8 times greater where phosphate was
deficient than were it was sufficent in the root environment. In young
corn leaves, 936 ppm of lead were found in the presence of adequate
phosphate while in phosphate deficient growth medium, the lead content
was 6,716 ppm.

E. Arsenic

The knowledge about the toxicity of arsenic is based on the use of
arsenicals over the years as insecticides, herbicides and defoliants.
Arsenic accumulates in soils to levels that may be phytotoxic. In
treated areas soils contain from 1.8 - 830 ppm arsenic, while untreated
areas had from 0.5 - 14.0 ppm arsenic.

In soils, toxic amounts of arsenic arrest the germination of seeds,
reduce the viability of seedlings and have the greatest effect at the
seedling stage. In soils the rate of nitrification in the presence of
arsenic is decreased and arsenic is toxic to nitrogen metabolism.

The concentration of soluble arsenic in soil necessary to cause
injury varies from 1 ppm for cowpeas, 9 ppm for peas and beans, 2 ppm
for barley, and 7 ppm for rice. Sodium arsenite applied to common field
sand at 1, 5 and 10 ppm reduced the yield of peas, beans, and corn.
Soil levels of 50 - 125 ppm of total arsenic may have a detrimental
effect on the growth of beans and strawberries. In apple orchards,
normal growth can be expected in soil with less than 50 ppm arsenic.
Soil with 50 - 100 ppm arsenic reduces growth 50 percent and soil with
over 100 ppm arsenic produces very little growth. Lead arsenate at I-
200 pounds per acre reduced the germination of string beans and lima
beans and retarded the seedling growth of many vegetables. Apple seed-

6

seeeenmnetetintewnnsteninntin iste imeipantesinnt dante nthe enfin a ceen


and turnips, contained 3.2 - 56 ppm cadmium. Greens with 56 ppm cadmium
were damaged.

Although the levels of cadmium in plant samples analyzed from the
Tacoma site are of questionable toxicity to plants, cadmium is present
in lettuce and cabbage in sufficient quantity to warrant toxicological
evaluations. Cadmium has been associated with a number of serious human
afflictions, e.g., hypertension, non-rheumatic heart disease, ostemalacia,
proteinuria and emphysema.

The values that are recommended or under discussion for maximum
allowable concentrations of cadmium in food is 135 micrograms per kilo-
gram (fresh weight) or approximately 1.35 parts per million (dry weight).
The cadmium levels in the cabbage family in the washed samples from
Tacoma ranged form 1.2 - 8.2 ppm (dry weight), with a mean value of 3.8
(dry weight), three to seven times higher than the maximum allowable
concentration.

D. Lead

Lead is present in all soils and plants. Soil contains an average
of 10-15 ppm and ranges from 2-200 ppm of lead.

In general, plants respond to lead only to a limited extent. For
example, the lead content of strawberries did not change when the lead
content of soil was increased from 8 to 59 ppm. In radishes a 10-fold
increase in soil lead content increased the lead concentration by a
factor of less than two.

The samples analyzed from Tacoma follow this pattern in that lead
values were essentially the same in cabbage cauliflower and brussel
sprouts regardless of the lead concentrations in the soil.


1. Report No. 2.
EPA-660/3-T4-012

BIBLIOGRAPHIC DATA
SHEET

3. Recipient's Accession No.

4. Title and Subtitle eayyeMetal Accumulation in Soil and Vegetation

from Smelter Emissions

5. Report Date
August 1974

6.

17. Author(s)
Hilman C. Ratsch

8. Performing Organization Rept.
0.

19. Performing Organization Name and Address
National Ecological Research Laboratory
Environmental Protection Agency
Corvallis, OR 97330

10. Project/Task/Work Unit No.
PE_1LAAOQO6 21 BCI-01

V1. Contract/Grant No.

12, Sponsoring Organization Name and Address

same

13. Type of Report & Period
Covered

Fihal

15. Supplementary Notes

16. Abstracts

transects radiating out from the Tacoma Smelter.

be related to distance from the smelter.
availability of metals to plants.

of heavy metals at levels toxic to some plants is shown.

Soil and plant samples were collected along north-south and northeast-southwest

The concentrations of lead, arsenic,
cadmium, and mercury in garden soil decline with increasing distance from the smelter.
The concentrations of arsenic and cadmium in vegetation also decrease at increasing
distance from the smelter, but lead and mercury concentrations did not appear to

The heavy-metal levels in the samples
demonstrate the accumulation of large amounts of metals in surface soils and the

When these values are compared to “average”
heavy-metal contents a deterioration of the quality of the soil and the presence:

17. Key Words and Document Analysis.

Heavy-metal accumulation
Air pollution

Vegetation effects

soil toxicity

copper smelter emissions

Wa. Descriptors

17b, Identifiers /Open-Ended Terms

heavy-metal accumulation in soils
heavy-metal accumulation in vegetation
air pollution

17e. COSATI Field/Group

78. Availability Statement
" Report)

19. Security Class (This
UNCLASSIFIED.

21. No. of Pages
23

20. Security Class (This
Page
*FINCLASSIFIED

22. Price

FORM NTIS35 (REV. S72)

USCOMM-DG 14052-P72



samples. A total of 68 vegetation and soil samples were collected or

received from Puget Sound Air Pollution Control Agency from within six

miles of the Tacoma smelter. A majority of the samples were taken from
residential gardens on two transects (N-S, NE-SW) at varying intervals

from the smelter. The soil samples of the top 0 - 2 inches were taken
immediately adjacent to the vegetation samples. All the samples were

analyzed by the Consolidated Laboratory Services, NERC-Corvallis using

atomic absorption spectroscopy for lead, cadmium, zinc, copper and

antimony; flameless atomic absorption for mercury and the Silver Diethyldithio-
carbamate colorometric method for arsenic determination.

On August 2 and October 25th and 26th, 1973, site visits were made
in the vicinity of the smelter. The area within a mile south and south-
west of the smelter is striking in that only a few species of vegetation
remain with a complete absence of legumes (alfalfa, clover, etc.) and
Douglas fir. The species that predominate are maple, oregon grape,
horsetail, Taurel hedge, bracken fern, scottish broom and native grasses.
At a greater distance from the smelter a larger variety of species is
observed, although Douglas fir is absent 4-5 miles southwest of the
smelter.

Vegetation injury reported over the years in the vicinity of the
smelter has been of the S05 and acid mist type. At the time of observation,
no SO, injury symptoms were observed on vegetation in the smelter vicinity.
Peach leaves showed some evidence of injury by acid mist, acid partic-
ulate or arsenic. At the Busic residence (5621 N. 46th ST.) margins of
peach leaves were red and showed small holes of necrotic tissue that
subsequently fell out of the leaf. Small bleached spots were seen
adjacent to the margins or covering the leaf. Marginal reddening of

nc ee ee


Fig. la

Arsenic concentration (ppm) in vegetation
in the Tacoma area.

COMMENCEMENT
35.8 BAY
°
54° 79.
nates
ee
52, 5.5
\e a —«
oN
e /N \
—tr6 [ee
=I \
q \ ) 1 1
[ cs eee |
Scale of miles
5,2 Pas
—e
TACOMA
16



Fig. 4a

Cadmium concentration (ppm) in vegetation
in the Tacoma area.

COMMENCEMENT
BAY

°
- 6.

9

3.2.
eee:

4,

|
>

82. —26

~1.5

24

\ fo) 1 We
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Scale of miles

TACOMA

Pe

22



ABSTRACT

Soil and plant samples were collected along north-south and northeast-
southwest transects radiating out from the Tacoma Smelter. The concen-
trations of lead, argenic, cadmium and mercury in garden soil decline
with increasing distance from the smelter. The concentrations of arsenic
and cadmium in vegetation also decrease at increasing distance from the
smelter, but lead and mercury concentrations did not appear to be related
to distance from the smelter.

The heavy-metal levels in the samples demonstrate the accumulation
of large amounts of metals in surface soils and the availability of
metals to plants. When these values are compared to "average" heavy-
metal contents a deterioration of the quality of the soil and the presence
of heavy-metals at levels toxic to some plants is shown.

ii


Results

Sample locations and concentrations of heavy metals in garden soil
and vegetation are shown in eight Figures la-4b and Tables I-III. The
highest concentrations of lead, arsenic, cadmium, and mercury in the
soil were found close to the smelter. Generally, concentrations of
lead, arsenic, cadmium and mercury decline with increasing distance from
the smelter, although concentrations at points 1/4 - 1/2 mile from the
smelter stack are consistently lower than those at approximately 1/2 - 1
mile due to plume rise and looping at distances from the smelter.

The arsenic concentrations of plant samples follow the same pattern
as the soil samples in that the highest levels are found closest to the
smelter, and the values decrease at increasing distance from the smelter.
The lead and mercury present in vegetation samples did not appear to be
related to distance from the stack. The highest mercury concentration
in the plant sample was found 2 1/2 miles from the smelter. The lead
concentrations in vegetation samples did not differ significantly regard-
less of location, even though the soil lead concentrations varied widely.
The concentration of cadmium in vegetation samples is apparently unrelated
to the distance from the smelter. The cadmium concentrations are high
in plant samples relative to related soil samples, indicating that the
vegetation is actively accumulating cadmium from soils acidified by
sulfuric acid.

The high concentrations of sulfur in the grass samples indicate a
substantial sulfur enrichment of vegetation, although injury symptoms on
vegetation from sulfur were not observed. The expected sulfur content
of grass is 2000 - 4000 ppm.


Conclusions

1. A major impact of the Tacoma smelter on the soil and vegetation
in the vicinity has been observed for many years. Sulfur dioxide emissions
over the years have degraded some plant species and altered the composi-
tion of plant communities. Heavy metals in soils in the smelter vicinity
have undoubtedly contributed to the degradation. With increased controls
on sulfur dioxide emissions, the heavy metals content in soil becomes more
important to soil toxicity and limits the restoration of natural plant
communities.

2. The heavy metals copper, arsenic and cadmium are present in
soils in concentrations that are likely to be toxic. These have suppressed
the establishment of natural and introduced plant species in contaminated
areas. Cadmium and mercury also represent a possible health hazard as
constituents of leafy vegetabies.

3. Sulfur dioxide probably will have a lesser effect on vegetation
as emission controls increase. Plant injury due to high pollution
episodes should decrease and be replaced by low level chronic type
injury.

il


EPA-660/3-74-012
August 1974

HEAVY-METAL ACCUMULATION IN SOIL AND VEGETATION
FROM SMELTER EMISSIONS

by

Hilman C. Ratsch
National Ecological Research Laboratory
Corvallis, Oregon 97330

Roap/Task 21BCI-01
Program Element 1AA006

NATIONAL ENVIRONMENTAL RESEARCH CENTER

OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OREGON 97330

For sale by the Superintendent of Documents, U.8. Government Printing Office, Washington, D.C. 20402 - Price 80 cents


Fig. 3a

Lead concentration (ppm) in vegetation

in the Tacoma area.

COMMENCEMENT
BAY

TACOMA

Pe

20

)
Ld
Scale of miles

We


RESEARCH REPORTING SERIES

Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:

1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research

4, Environmental Monitoring

5. Socioeconomic Environmental Studies

This report has been assigned to the ECOLOGICAL
RESEARCH series. This series describes research
on the effects of pollution on humans, plant and
animal species, and materials. Problems are
assessed for their long- and short-term
influences. Investigations include formaticn,
transport, and pathway studies to determine the
fate of pollutants and their effects. This work
provides the technical basis for setting standards
to minimize undesirable changes in living
organisms in the aquatic, terrestrial and
atmospheric environments.

EPA REVIEW NOTICE

The Office of Research and Development has reviewed this
report and approved its publication. Mention of trade names
or commercial products does not constitute endorsement or
recommendation for use.


Fig. 4b

Cadmium concentration (ppm) in garden
soils in the Tacoma area.

COMMENCEMENT
8 BAY
<oar-)
7. ue
pg xis
| -1L0
6 —_ —23
RS 5 a
€ |
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TACOMA

a

23



lings grown in potted soil with 100 - 160 ppm Sodium arsenate were
killed. Corn kernels rarely develop at soil concentrations of 80 - 100
ppm arsenic.

The chemical form of arsenic is more important than the total soi]
arsenic in phytoxic effect. The formation of arsenic compounds is
affected by acidity, Fe, Al, Ca, P and humus content of the soil. Soils
with high reactive aluminum levels are less phytotoxic even after heavy
applications of arsenic. Six of the cabbage and lettuce samples from
Tacoma exceed the arsenic tolerance levels and are a possible health
hazard.

Arsenic is present in the soil and plant tissue from Tacoma at
levels that can be toxic to sensitive and moderately sensitive plant
species. Snap bean, lima bean, onion, peas, cucumber, alfalfa and other
legumes are highly sensitive to water soluble arsenic. This may account
for the fact that legumes are absent from the vicinity of the smelter.

F. Mercury

The mercury content of soils in the United States range from 10-500
ppb, and average 100 ppb. Mercury tends to be retained in the surface
layers of the soil due to adsorption by organic and inorganic materials
and the low solubilities of mercury salts (phosphate, carbonate, sulfide).

In most plants mercury concentrations range from 10-200 ppb (15 ppb
ave.), but plants growing near mercury deposits can contain 500-3500 ppb
mercury. Translocation of mercury occurs in many plant tissues, including
leaves, fruit and tubers.

Toxicity of mercury to terrestrial plants apparently depends more
on chemical form than on its concentration. There are but a few studies
available on the toxicity of mercury to specific plants, but small

7


The analysis of vegetation and soil samples demonstrate the accumulation
of high concentrations of heavy metals in surface soils and the avail-
ability of these metals to plants. The heavy metal content of these
samples from the Tacoma sites are many times greater for the "average"
all elements analyzed with the possible exception of zinc. All of the
elements measured may be toxic to one or more plant species.

Control Measures
Methods of altering soil chemistry are available to minimize or
reduce heavy metal uptake by plants from soil. The addition of lime is
a common measure used to reduce metal uptake by
1. Decreasing the soil acidity to pH 6.5 may resuit in the precipitation
of heavy metals as hydroxides, carbonates, phosphates, etc., and in

immobilizing the heavy metal ions.

2. Cations will compete with the trace elements in the soil for
exchange sites of the soil and root surfaces.

3. Liming may promote the capacity of plant roots to form complexes
with metal ions.

Adding soil phosphates may be a means to precipitate heavy metals
as compounds of limited availability to plants.

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