- Email: [email protected]
Migration of lead and arsenic in old orchard soils in the Georgian Bay region of Ontario
Chemosphere, Vol. 29, No. 2, pp. 407-413, 1994 Elsevier Science Lid Printed in Great B~itain 0045-6535/94 $7.00+0.00
Pergamon
0045-6535(94)00173-1
MIGRATION OF LEAD AND A R S M I I C I N OLD OAC~tRD S O I L S I N THB GBORGIAN BAY RBGION OF ONTARIO
Don C. Elfvlng, l* Kenneth R. Wilson, = Joseph G. Bbel, Jr., 3 Kerry L. Manze11, 3 walter H. Gutenmann 4 and Donald J. L i s ~ * * IHorticultural Research Institute of Ontario, Ministry of Agriculture and Food Vineland Station, Ontario LOR 2EO 2plant Industry Branch, Ministry of Agriculture and Food Clarksburg, Ontario NOH iJO ~ e t e r i n a r y Diagnostic Laboratory, Division of Toxlcology New York State College of Veterinary Medicine ~ o x l c Chemicals Laboratory, New York State College of Agriculture and Life Sciences Cornell University, Ithaca, Hew York 14853 (Receiv~ m USA 12J~uary1994;accepmd30March1994) ABSTIOkCT Lead arsenate was used for insect control in apple and other fruit orchards for many years. To determine the magnitude and migration of remaining soll residues of arsenic and lead, samples of a clay and a sandy soll were taken at increasing depths at 10 orchard sites in the Georgian Bay region of Ontario, Canada, 5 in which either the clay or sandy soll types were located. The rate of decrease in concentration of each element with depth was significantly greater in the sand than in the clay suggesting that downward movement of both elements occurred less readily in the sandy soil. In each soil type, the rate of decrease in concentration of lead with depth was significantly greater than for arsenic suggesting that lead was lees mobile than arsenic in the soil profile regardless of texture. The toxic effects of arsenic and lead in orchard soils on plants and animals are discussed. INTRODUCTION Long before the advent of DDT, and for many years thereafter,
lead arsenate was commonly used
for control of pests in apple and other fruit orchards (Peryea 1991a).
Phytotoxiclty to newly
planted fruit tree seedlings or other crops from arsenic residues in such orchard soils (Vandecaveye et al. 1937; Benson 1968; Sheppard 1992) is well known.
More recently, there is
concern about possible adverse health effects in humans, grazing animals and wildlife inhabiting such areas which residences, gardens or forage crops may now occupy.
It was
therefore of interest to determine the magnitude of downward migration of remaining soil residues of arsenic and lead at such old orchard sites.
In the work reported here, arsenic
and lead were determined in samples of two soil types, a clay and a sand, taken at increasing depths at sites in 10 apple orchards, BXPRRIJmHTRL
5 in which either the clay or the sand were located.
The sol1 samples were collected from 10 apple orchards in the area along the southern perimeter of Georgian Bay in Ontario, Canada.
The orchards were 65 years or older and the
sampling sites had not been disturbed during the llfe of the orchards. each orchard was Northern Spy on seedling rootstock.
The apple cultivar in
The soils were Brighton sand (dysic,
*Present address= Tree Fruit Research & Extension Center, Washington State University, Wenatchee, WA 98801 **Address all correspondence
407
408 hyperthermic typic medifibrists),
pH 6.0, at 5 sites and Vincent clay loam (fine, mixed, mesic
typic hapludalfs),
pH 6.8, at the remaining five.
in all instances.
The depths sampled were 0-2 in. (0-5.1 om), 2-4 in.
(10.2-15.2 om), 6-8 in.
Soil samples were taken from tree driplines (5.1-10.2 om), 4-6 in.
(15.2-20.3 om), 8-10 in. (20.3-25.4 cm) and 10-12 in.
(25.4-30.5 cm).
At each site, i0 subeamplea were taken and combined to form a representative sample. The samples were air-dried,
aggregates crushed with a rolling pin, sieved through a 2 mm
screen, ground to a fine powdery consistency in a mortar end pestle, mixed by tumbling and 0.5 g was subeampled for analysis.
The subsample was transferred to a KJeldahl flask, 5 ml of
concentrated nitric acid and 2 ml of 70% perchloric acld were added, the mixture was heated until white fumes of perchloric acid appeared and was then refluxed for 30 minutes.
Digestion
with nitric and perchlorlc acids has been shown to release 98% of total soil lead as compared to digestion with nitric acid, potassium perchlorate and hydrofluoric acid ( V e n ~ a n 1982).
The digests were diluted to 25 ml with 1 N hydrochlorlc acid and mixed.
lead were determined in the supernatant solution, respectively, thermal
etal.
Arsenic and
by Zeeman effect electro-
(Eckerlin et el. 1987) and flame atomic absorption apectrophotometry.
Non-radlatlng regression analyses on mean sample depth assessed the presence of significant linear and curvilinear relations between sample depth and lead or arsenic concentration in two soil types
(Snedecor and Cochran 1980).
regression intercepts,
Separate analyses examined the homogeneity of
slopes, and second-order curvatures for the response of lead or arsenic
concentrations to depth in the two soil types. concentrations with depth in each soil. Linear Models
Similar analyses compared lead or arsenic
Statistical analyses were performed using the General
(GLM) procedure of the Statistical Analysis System program package
(8AS
Institute, Cary, NC). RBBDL.TN AND D I S C U S S I O N
Levels of both lead and arsenic were substantially higher in the uppermost layers of the Brighton sand compared to the Vincent clay loam.
These differences may reflect total amounts
of lead arsenate applied to the orchards in the past.
In both soils, lead and arsenic
concentrations decreased linearly with greater depth to about 30 cm.
The rate of decrease in
concentration of each element with depth (regression slope} was algnificantly greater in the Brighton sand than in the Vincent clay loam, suggesting that downward movement of both elements o c c u r r e d less readily in the sandy soil (Figures 1 and 2).
In each soil type, the
rate of decrease in concentration of lead with depth was signiflcantly greater than for arsenic, suggesting that lead was less mobile than arsenic in the sol1 profile regardless of texture.
This interpretation assumes that all lead and arsenic residues originated from
applications of lead arsenate. Highest soil concentrations of arsenic and lead in an old apple orchard were reported at low spots and former tree sites especially under the drIpline (Veneman et el. 1983}.
Progressive-
ly decreasing residues of arsenic and lead with increasing sampling depth in old lead arsenate-treated apple orchard soils have been reported (Aten e t a l . Veneman e t a l .
1983).
1980; Frank e t a l .
1976;
The more facile mobility of arsenic compared to lead in soils has also
been reported by Sheppard
(1992).
However, movement of soil particles and elements between
horizons by the activities of earthworms and other soil animals accompanied by their differential storage and excretion of the elements they absorb from the soil may confound attempts to compare the relative migration rates of arsenic and lead. There are numerous possible sources of error when one undertakes a study of the concentrations and downward migration of arsenic and particularly lead in old orchard soils.
Since records
of past spray history may be nonexistent or incomplete, one may only be able to estimate the past total quantity of arsenic or lead applied.
Whether the soil was truly undisturbed over
the life of the orchard or instead plowed or disked may be uncertain.
Other sources of lead
4O9
240 -210-
X = Brightonsand
X
•
=
Vincent clay loam
180E
Q.
Y = 209.1 - 7.1X
150120--
X 8
900
I1
6030-
°o
"''0..... Y = 72.5
'
X
- 2.0X
~X - . . p
,'o ," :o
'o
Soil depth (cm)
Figure 1.
C o n c e n t r a t i o n of lead in two o r c h a r d soils as a f u n c t i o n of s a m p l e depth.
n o n - r a d i a t l n g r e g r e s s i o n m o d e l r z= .52.
Overall
410
X = B r i g h t o n sand
48-
@ = V i n c e n t c l a y loam
X
42-
X 36-
X Q. p,
Y = 47.4 - 1.2X
30-
o
X
24-0 t-
18-Y = 14.8 - 0.3X
12--
+'--o...9 "'4t
X X " 0 " - .@
6 ~IIIB
°0
,' 2'0 '5 "0 Soil depth (cm)
Figure 2.
C o n c e n t r a t i o n of arsenic in two orchard soils as a f u n c t i o n of sample depth.
Overall n o n - r a d i a t i n g r e g r e s s i o n model r2= .46.
411 such am vehicle exhaust or sewage sludge applications may be involved.
Whem sampling soil
near the surface one could unknowingly include lead shot from past hunting in the area.
When
sampling soil at increasing depths, care must be taken to avoid soil particles from upper layers falling down and being inadvertently sampled at lower depths.
Sampling by driving in a
plastic pipe and then extruding the soll plug with analysis of sections representing desired depths can obviate thi~ problem but large stones in the soil profile may prevent this sampling procedure. Several studies have dealt with the toxic effects of arsenic and lead in old orchard soils on plants and animals.
The magnitude of uptake of arsenic and lead by vegetable and fruit cropB
grown on old lead arsenate-treated apple orchard soils has been investigated. and onion bulbs, having been peeled, contained, respectively, and 7.1 and 0.8 ppm of lead when grown on a silt loam soil.
Carrot roots
0.9 and 0.4 ppm dry wt arsenic Whereas residues of arsenic and
lead were negligible or very low in the edible portion of beans, cabbage, potatoes and tomatoes, the concentration of arsenic and lead (ppm, dry wt) in carrot roots were, respectlvely, 0.9 and 6.1 and arsenic in onion bulbs was 0.3 (Elfving st al.
1978).
Regarding
analysis of plants grown on such soils for arsenic or lead, it is possible to analyze roots of vegetables such as carrots or radishes if they are first cleaned and peeled to remove adhering soil particles.
It is very difficult to completely remove all adhering and embedded soil
particles from fibrous roots of, for instance, grasses, prior to analysis for elements that are taken up and stored in roots.
Of course above ground portion of plants must also be
washed free of adhering soil particles prior to analysis. Apple leaf, peel and pulp as well as potato leaf and peel were significantly higher in arsenic residues when grown on recently arsenic-treated orchard soils (MacLean and Langille 1981). Arsenic in apricot and apple fruit grown on old lead arsenate-contaminated
orchard soils was
reported to be positively correlated with concentrated HCl-extractable soil arsenic while lead in these fruits was not detectable
(Creger and Peryea 1992).
However,
levels of arsenic and
lead found in crops grown in all of the above orchard soil studies would not be considered of health significance. Sheppard (1992) comprehensively surveyed the literature dealing with phytotoxicity of arsenic in soils.
Arsenic has low mobility in soils.
than organic sources.
Inorganic sources of arsenic are less toxic
Considering inorganic sources, arsenic is more phytotoxic in sands and
loams (the mean concentrations being about 40 mg/kg) than in clay soils (the mean concentration being about 200 mg/kg).
Monocotyledonous and dicotyledonous plants are about equally
susceptible to arsenic phytotoxicity
(Sheppard 1991).
Soil remediation was recommended when
the concentration of arsenic in soil was only 2.5-fold above the background level
(Scharpen-
seel and Becker-Heidmann 1990). Release of arsenic from lead arsenate-contaminated soil has been reported to be positively related to fertilization with monoammonium phosphate and monocalcium phosphate
(Peryea 1991a).
It has been suggested that use of phosphate fertilizers on lead arsenate contaminated soils may temporarily enhance potential for arsenic phytotoxicity or arsenic contamination of groundwater
(Davenport and Peryea 1991).
Interestingly,
however, wheat seedlings in nutrient
solution cultures were reported to be protected against phytotoxicity by arsenic if sufficient phosphorus was also present in the solution (Hurd-Karrer 1936). arsenic from lead arsenate-contaminated
Significant removal of
soils has been accomplished by amending the soils with
apple pomace as a carbon source and flooding them. arsenic and evolution of methylarsine occurs
Under these conditions biomethylation of
(Peryea 1991b).
Arsenic and lead in lead arsenate-treated soils can also affect soil animals and their predators.
Earthworms have been shown to concentrate lead from soils (Ash and Lee 1980;
412 Morgan and Morgan 1988; Gish and Christensen 1973; Beyer and Cromartie 1987; Ireland 1979). Elfvlsg et al.
(1978; 1979) and Haschek et al. (1979) showed that meadow voles trapped in two
old orchards were n~trkedly higher in lead in kidney, liver and bone (the latter up to 300 ppe) than in control animutls (up to 33 ppe in bone).
Intranuclear inclusion bodies diagnostic of
lead poisoning were found in renal epithelial cells of the proximal convoluted tubules in v~lee from the lead arsenate-treated orchards. for 86 days,
lead concentrations
When laboratory cats were fed the above voles
increased 5 to 10 fold in their kidney,
compared to oats fed a control diet (Gilmartln e t a / .
1985}.
liver and bone as
Similarly, whole body burdens of
arsenic in voles and mice trapped in such orchards were found to parallel the concentrations of arsenic in the orchard soll (Elfvlng et al. 1979). they p r e s ~ b l y
Since these animals are subterranean,
become contaminated by inadvertent ingestion of arsenic and lead-ladened soil
particles as they forage on soil insects and plant root material.
Predators of these animals
such as oavls, hawks and foxes would undoubtedly concentrate lead as was found with the cats that were experlsmntally
fed meadow voles.
Of course, the levels of arsenic and lead found in
small soil animals (and therefore their predators) would depend on whether they inhabited old orchard soils exclusively throughout their lifetimes or if instead their home range at times exceeded the boundaries of such lead arsenate-treated areas. expectedly concentrate lead if the ~oll was contaminated.
Worm-eating birds would also
If orchard trees are removed, and
the soils cultivated and forage crops planted, grazing animals can be exposed to arsenic and lead.
Aside from possible uptake of these elecnents by forage crops, ruminants and horses tear
out plants by the roots while grazing, unlntentlona11y consuming significant quantities of sol1 that is occluded to plant roots (McGrath et al. 1982).
This problem is particularly of
concern where expensive animals such as race horses are involved. Finally, there is m u c h concern presently about the posslble human health effects of lead.
If
residences are built on old orchard soils, concern arises about contamination of garden crops and hand-to-mouth intake of soll by children frequenting such areas.
Studies pertaining to
risk assessment of lead in soil as regards children's health has been done (Hawley, Madhaven et al. 1989; van Wijen et al. 1990).
Interestingly, Nelson et al.
1985;
(1973} reported
that a study of orchardists who had used lead arsenate for periods up to 21 years or longer showed no clear relationship between exposure times and health effects vascular lesions,
(heart disease,
cancer) or longevity as compared to an unexposed group.
Rm~mIN~S
Ash CPJ, Lee DL (1980) Environ Pollut 22A:59-67 Aten CF, Bourke JB, Martini JH, Walton JC (1980} Bull Environm Contam Toxicol 24:108-115 Benson NR (1968) Proc Wash State Hort Assoc 64:lE-SE Beyer WN, Cromartle EJ (1987) Environ Monitor Assess 8:27-36 Creger TL, Peryea FJ (1992) HortSclence 27(12):1277-1278 Davenport JR, Peryea FJ (1991) Water, Air Soil Pollut 57-58:101-110 Eckerlin RH, Hoult DW, Carnrick GR (1987) Atomic Spect 8(1):64-66 Elfvlng DC, Haschek WM, Stehn RA, Bathe CA, Lisk DJ (1978) Arch Environ Health 33:95-99 Elfvlng DC, Stehn RA, Pakkala IS, Lisk DJ (1979) Bull Environ Contam Toxicol 21:62-64 Frank R, Braun HE, Ishida K, Suds P (1976) Can J Soil Scl 56:463-484 Gilmartln JE, Alo DK, Richmond ME, Bachs CA, Lisk DJ (1985) Bull Environ Contam Toxicol 34:291-294 Gish CD, Chrlstensen HE (1973) Environ Scl Technol 7:1060-1062 Haschek WM, Lisk DJ, Stehn RA (1979) " A c c u m u l a t i o n s
of Lead in Rodents from Two Old Orchard
Sites in New York" in A n i m a l s as m o n i t o r s of e n v i r o n m e n t a l Washington,
DC, pp 192-199
Hawley JK (1985) Risk Anal 5(4):289-301 Hurd-Karrer AM (1936) J Wash Acad Sci 26(4):180-181 Ireland MP (1979) Environ Pollut 13:201-206 MacLean KS, Langille SM (1981) Plant & Soil 61:413-418
pollutants,
Nat Acad Sci,
413 Madhaven S, Romenman KD, Shehata T (1989) Environ Re8 49:136-142 McGrath D, Poole DBR, Fleming GA, Sinnott J (1982} Ir J Agric Res 21:135-145 Morgan JE, Morgan AJ (1988} Environ Pollut 54:123-138 Nelson WC, Lykin8 MH, Mackay J, Newill VA, Finklea JF, H~umner DI (1973} J Chron Dis 26:105-118 Peryea FJ (1991a) Soll Scl Soc Am J 55(5):1301-1306 Peryea FJ (1991b)
"Bior@m@dlation of Lead Arsenate-Contamlnated Soils", US Dept Interior Grant
No. G1597-03, Water Research Center Project No. A-168-WASH,
30 pages
sheppard SC (1992) Water, Air, sol1 Pollut 54:539-550 Snedecor, GW, Cochran WG (1980} Statistical Methods,
7th ed. Section 18.9.
Iowa State Univ
Press, Ames, pp. 385-388 van Wijnen JH, Clausing P, Brunekreef B (1990} Environ Re8 51:147-162 Vandacaveye SC, Horner GM, Keaton CM (1936} Soil Scl 42:203-215 Veneman PLM, Bodine SM, Murray JR, Baker JH (1982) Coamun in Soll Sci Plant Anal 13(8}:585-592 Veneman PLM, Murray JR, Baker JH (1983) J Environ Qual 12(1):101-104
Pergamon
0045-6535(94)00173-1
MIGRATION OF LEAD AND A R S M I I C I N OLD OAC~tRD S O I L S I N THB GBORGIAN BAY RBGION OF ONTARIO
Don C. Elfvlng, l* Kenneth R. Wilson, = Joseph G. Bbel, Jr., 3 Kerry L. Manze11, 3 walter H. Gutenmann 4 and Donald J. L i s ~ * * IHorticultural Research Institute of Ontario, Ministry of Agriculture and Food Vineland Station, Ontario LOR 2EO 2plant Industry Branch, Ministry of Agriculture and Food Clarksburg, Ontario NOH iJO ~ e t e r i n a r y Diagnostic Laboratory, Division of Toxlcology New York State College of Veterinary Medicine ~ o x l c Chemicals Laboratory, New York State College of Agriculture and Life Sciences Cornell University, Ithaca, Hew York 14853 (Receiv~ m USA 12J~uary1994;accepmd30March1994) ABSTIOkCT Lead arsenate was used for insect control in apple and other fruit orchards for many years. To determine the magnitude and migration of remaining soll residues of arsenic and lead, samples of a clay and a sandy soll were taken at increasing depths at 10 orchard sites in the Georgian Bay region of Ontario, Canada, 5 in which either the clay or sandy soll types were located. The rate of decrease in concentration of each element with depth was significantly greater in the sand than in the clay suggesting that downward movement of both elements occurred less readily in the sandy soil. In each soil type, the rate of decrease in concentration of lead with depth was significantly greater than for arsenic suggesting that lead was lees mobile than arsenic in the soil profile regardless of texture. The toxic effects of arsenic and lead in orchard soils on plants and animals are discussed. INTRODUCTION Long before the advent of DDT, and for many years thereafter,
lead arsenate was commonly used
for control of pests in apple and other fruit orchards (Peryea 1991a).
Phytotoxiclty to newly
planted fruit tree seedlings or other crops from arsenic residues in such orchard soils (Vandecaveye et al. 1937; Benson 1968; Sheppard 1992) is well known.
More recently, there is
concern about possible adverse health effects in humans, grazing animals and wildlife inhabiting such areas which residences, gardens or forage crops may now occupy.
It was
therefore of interest to determine the magnitude of downward migration of remaining soil residues of arsenic and lead at such old orchard sites.
In the work reported here, arsenic
and lead were determined in samples of two soil types, a clay and a sand, taken at increasing depths at sites in 10 apple orchards, BXPRRIJmHTRL
5 in which either the clay or the sand were located.
The sol1 samples were collected from 10 apple orchards in the area along the southern perimeter of Georgian Bay in Ontario, Canada.
The orchards were 65 years or older and the
sampling sites had not been disturbed during the llfe of the orchards. each orchard was Northern Spy on seedling rootstock.
The apple cultivar in
The soils were Brighton sand (dysic,
*Present address= Tree Fruit Research & Extension Center, Washington State University, Wenatchee, WA 98801 **Address all correspondence
407
408 hyperthermic typic medifibrists),
pH 6.0, at 5 sites and Vincent clay loam (fine, mixed, mesic
typic hapludalfs),
pH 6.8, at the remaining five.
in all instances.
The depths sampled were 0-2 in. (0-5.1 om), 2-4 in.
(10.2-15.2 om), 6-8 in.
Soil samples were taken from tree driplines (5.1-10.2 om), 4-6 in.
(15.2-20.3 om), 8-10 in. (20.3-25.4 cm) and 10-12 in.
(25.4-30.5 cm).
At each site, i0 subeamplea were taken and combined to form a representative sample. The samples were air-dried,
aggregates crushed with a rolling pin, sieved through a 2 mm
screen, ground to a fine powdery consistency in a mortar end pestle, mixed by tumbling and 0.5 g was subeampled for analysis.
The subsample was transferred to a KJeldahl flask, 5 ml of
concentrated nitric acid and 2 ml of 70% perchloric acld were added, the mixture was heated until white fumes of perchloric acid appeared and was then refluxed for 30 minutes.
Digestion
with nitric and perchlorlc acids has been shown to release 98% of total soil lead as compared to digestion with nitric acid, potassium perchlorate and hydrofluoric acid ( V e n ~ a n 1982).
The digests were diluted to 25 ml with 1 N hydrochlorlc acid and mixed.
lead were determined in the supernatant solution, respectively, thermal
etal.
Arsenic and
by Zeeman effect electro-
(Eckerlin et el. 1987) and flame atomic absorption apectrophotometry.
Non-radlatlng regression analyses on mean sample depth assessed the presence of significant linear and curvilinear relations between sample depth and lead or arsenic concentration in two soil types
(Snedecor and Cochran 1980).
regression intercepts,
Separate analyses examined the homogeneity of
slopes, and second-order curvatures for the response of lead or arsenic
concentrations to depth in the two soil types. concentrations with depth in each soil. Linear Models
Similar analyses compared lead or arsenic
Statistical analyses were performed using the General
(GLM) procedure of the Statistical Analysis System program package
(8AS
Institute, Cary, NC). RBBDL.TN AND D I S C U S S I O N
Levels of both lead and arsenic were substantially higher in the uppermost layers of the Brighton sand compared to the Vincent clay loam.
These differences may reflect total amounts
of lead arsenate applied to the orchards in the past.
In both soils, lead and arsenic
concentrations decreased linearly with greater depth to about 30 cm.
The rate of decrease in
concentration of each element with depth (regression slope} was algnificantly greater in the Brighton sand than in the Vincent clay loam, suggesting that downward movement of both elements o c c u r r e d less readily in the sandy soil (Figures 1 and 2).
In each soil type, the
rate of decrease in concentration of lead with depth was signiflcantly greater than for arsenic, suggesting that lead was less mobile than arsenic in the sol1 profile regardless of texture.
This interpretation assumes that all lead and arsenic residues originated from
applications of lead arsenate. Highest soil concentrations of arsenic and lead in an old apple orchard were reported at low spots and former tree sites especially under the drIpline (Veneman et el. 1983}.
Progressive-
ly decreasing residues of arsenic and lead with increasing sampling depth in old lead arsenate-treated apple orchard soils have been reported (Aten e t a l . Veneman e t a l .
1983).
1980; Frank e t a l .
1976;
The more facile mobility of arsenic compared to lead in soils has also
been reported by Sheppard
(1992).
However, movement of soil particles and elements between
horizons by the activities of earthworms and other soil animals accompanied by their differential storage and excretion of the elements they absorb from the soil may confound attempts to compare the relative migration rates of arsenic and lead. There are numerous possible sources of error when one undertakes a study of the concentrations and downward migration of arsenic and particularly lead in old orchard soils.
Since records
of past spray history may be nonexistent or incomplete, one may only be able to estimate the past total quantity of arsenic or lead applied.
Whether the soil was truly undisturbed over
the life of the orchard or instead plowed or disked may be uncertain.
Other sources of lead
4O9
240 -210-
X = Brightonsand
X
•
=
Vincent clay loam
180E
Q.
Y = 209.1 - 7.1X
150120--
X 8
900
I1
6030-
°o
"''0..... Y = 72.5
'
X
- 2.0X
~X - . . p
,'o ," :o
'o
Soil depth (cm)
Figure 1.
C o n c e n t r a t i o n of lead in two o r c h a r d soils as a f u n c t i o n of s a m p l e depth.
n o n - r a d i a t l n g r e g r e s s i o n m o d e l r z= .52.
Overall
410
X = B r i g h t o n sand
48-
@ = V i n c e n t c l a y loam
X
42-
X 36-
X Q. p,
Y = 47.4 - 1.2X
30-
o
X
24-0 t-
18-Y = 14.8 - 0.3X
12--
+'--o...9 "'4t
X X " 0 " - .@
6 ~IIIB
°0
,' 2'0 '5 "0 Soil depth (cm)
Figure 2.
C o n c e n t r a t i o n of arsenic in two orchard soils as a f u n c t i o n of sample depth.
Overall n o n - r a d i a t i n g r e g r e s s i o n model r2= .46.
411 such am vehicle exhaust or sewage sludge applications may be involved.
Whem sampling soil
near the surface one could unknowingly include lead shot from past hunting in the area.
When
sampling soil at increasing depths, care must be taken to avoid soil particles from upper layers falling down and being inadvertently sampled at lower depths.
Sampling by driving in a
plastic pipe and then extruding the soll plug with analysis of sections representing desired depths can obviate thi~ problem but large stones in the soil profile may prevent this sampling procedure. Several studies have dealt with the toxic effects of arsenic and lead in old orchard soils on plants and animals.
The magnitude of uptake of arsenic and lead by vegetable and fruit cropB
grown on old lead arsenate-treated apple orchard soils has been investigated. and onion bulbs, having been peeled, contained, respectively, and 7.1 and 0.8 ppm of lead when grown on a silt loam soil.
Carrot roots
0.9 and 0.4 ppm dry wt arsenic Whereas residues of arsenic and
lead were negligible or very low in the edible portion of beans, cabbage, potatoes and tomatoes, the concentration of arsenic and lead (ppm, dry wt) in carrot roots were, respectlvely, 0.9 and 6.1 and arsenic in onion bulbs was 0.3 (Elfving st al.
1978).
Regarding
analysis of plants grown on such soils for arsenic or lead, it is possible to analyze roots of vegetables such as carrots or radishes if they are first cleaned and peeled to remove adhering soil particles.
It is very difficult to completely remove all adhering and embedded soil
particles from fibrous roots of, for instance, grasses, prior to analysis for elements that are taken up and stored in roots.
Of course above ground portion of plants must also be
washed free of adhering soil particles prior to analysis. Apple leaf, peel and pulp as well as potato leaf and peel were significantly higher in arsenic residues when grown on recently arsenic-treated orchard soils (MacLean and Langille 1981). Arsenic in apricot and apple fruit grown on old lead arsenate-contaminated
orchard soils was
reported to be positively correlated with concentrated HCl-extractable soil arsenic while lead in these fruits was not detectable
(Creger and Peryea 1992).
However,
levels of arsenic and
lead found in crops grown in all of the above orchard soil studies would not be considered of health significance. Sheppard (1992) comprehensively surveyed the literature dealing with phytotoxicity of arsenic in soils.
Arsenic has low mobility in soils.
than organic sources.
Inorganic sources of arsenic are less toxic
Considering inorganic sources, arsenic is more phytotoxic in sands and
loams (the mean concentrations being about 40 mg/kg) than in clay soils (the mean concentration being about 200 mg/kg).
Monocotyledonous and dicotyledonous plants are about equally
susceptible to arsenic phytotoxicity
(Sheppard 1991).
Soil remediation was recommended when
the concentration of arsenic in soil was only 2.5-fold above the background level
(Scharpen-
seel and Becker-Heidmann 1990). Release of arsenic from lead arsenate-contaminated soil has been reported to be positively related to fertilization with monoammonium phosphate and monocalcium phosphate
(Peryea 1991a).
It has been suggested that use of phosphate fertilizers on lead arsenate contaminated soils may temporarily enhance potential for arsenic phytotoxicity or arsenic contamination of groundwater
(Davenport and Peryea 1991).
Interestingly,
however, wheat seedlings in nutrient
solution cultures were reported to be protected against phytotoxicity by arsenic if sufficient phosphorus was also present in the solution (Hurd-Karrer 1936). arsenic from lead arsenate-contaminated
Significant removal of
soils has been accomplished by amending the soils with
apple pomace as a carbon source and flooding them. arsenic and evolution of methylarsine occurs
Under these conditions biomethylation of
(Peryea 1991b).
Arsenic and lead in lead arsenate-treated soils can also affect soil animals and their predators.
Earthworms have been shown to concentrate lead from soils (Ash and Lee 1980;
412 Morgan and Morgan 1988; Gish and Christensen 1973; Beyer and Cromartie 1987; Ireland 1979). Elfvlsg et al.
(1978; 1979) and Haschek et al. (1979) showed that meadow voles trapped in two
old orchards were n~trkedly higher in lead in kidney, liver and bone (the latter up to 300 ppe) than in control animutls (up to 33 ppe in bone).
Intranuclear inclusion bodies diagnostic of
lead poisoning were found in renal epithelial cells of the proximal convoluted tubules in v~lee from the lead arsenate-treated orchards. for 86 days,
lead concentrations
When laboratory cats were fed the above voles
increased 5 to 10 fold in their kidney,
compared to oats fed a control diet (Gilmartln e t a / .
1985}.
liver and bone as
Similarly, whole body burdens of
arsenic in voles and mice trapped in such orchards were found to parallel the concentrations of arsenic in the orchard soll (Elfvlng et al. 1979). they p r e s ~ b l y
Since these animals are subterranean,
become contaminated by inadvertent ingestion of arsenic and lead-ladened soil
particles as they forage on soil insects and plant root material.
Predators of these animals
such as oavls, hawks and foxes would undoubtedly concentrate lead as was found with the cats that were experlsmntally
fed meadow voles.
Of course, the levels of arsenic and lead found in
small soil animals (and therefore their predators) would depend on whether they inhabited old orchard soils exclusively throughout their lifetimes or if instead their home range at times exceeded the boundaries of such lead arsenate-treated areas. expectedly concentrate lead if the ~oll was contaminated.
Worm-eating birds would also
If orchard trees are removed, and
the soils cultivated and forage crops planted, grazing animals can be exposed to arsenic and lead.
Aside from possible uptake of these elecnents by forage crops, ruminants and horses tear
out plants by the roots while grazing, unlntentlona11y consuming significant quantities of sol1 that is occluded to plant roots (McGrath et al. 1982).
This problem is particularly of
concern where expensive animals such as race horses are involved. Finally, there is m u c h concern presently about the posslble human health effects of lead.
If
residences are built on old orchard soils, concern arises about contamination of garden crops and hand-to-mouth intake of soll by children frequenting such areas.
Studies pertaining to
risk assessment of lead in soil as regards children's health has been done (Hawley, Madhaven et al. 1989; van Wijen et al. 1990).
Interestingly, Nelson et al.
1985;
(1973} reported
that a study of orchardists who had used lead arsenate for periods up to 21 years or longer showed no clear relationship between exposure times and health effects vascular lesions,
(heart disease,
cancer) or longevity as compared to an unexposed group.
Rm~mIN~S
Ash CPJ, Lee DL (1980) Environ Pollut 22A:59-67 Aten CF, Bourke JB, Martini JH, Walton JC (1980} Bull Environm Contam Toxicol 24:108-115 Benson NR (1968) Proc Wash State Hort Assoc 64:lE-SE Beyer WN, Cromartle EJ (1987) Environ Monitor Assess 8:27-36 Creger TL, Peryea FJ (1992) HortSclence 27(12):1277-1278 Davenport JR, Peryea FJ (1991) Water, Air Soil Pollut 57-58:101-110 Eckerlin RH, Hoult DW, Carnrick GR (1987) Atomic Spect 8(1):64-66 Elfvlng DC, Haschek WM, Stehn RA, Bathe CA, Lisk DJ (1978) Arch Environ Health 33:95-99 Elfvlng DC, Stehn RA, Pakkala IS, Lisk DJ (1979) Bull Environ Contam Toxicol 21:62-64 Frank R, Braun HE, Ishida K, Suds P (1976) Can J Soil Scl 56:463-484 Gilmartln JE, Alo DK, Richmond ME, Bachs CA, Lisk DJ (1985) Bull Environ Contam Toxicol 34:291-294 Gish CD, Chrlstensen HE (1973) Environ Scl Technol 7:1060-1062 Haschek WM, Lisk DJ, Stehn RA (1979) " A c c u m u l a t i o n s
of Lead in Rodents from Two Old Orchard
Sites in New York" in A n i m a l s as m o n i t o r s of e n v i r o n m e n t a l Washington,
DC, pp 192-199
Hawley JK (1985) Risk Anal 5(4):289-301 Hurd-Karrer AM (1936) J Wash Acad Sci 26(4):180-181 Ireland MP (1979) Environ Pollut 13:201-206 MacLean KS, Langille SM (1981) Plant & Soil 61:413-418
pollutants,
Nat Acad Sci,
413 Madhaven S, Romenman KD, Shehata T (1989) Environ Re8 49:136-142 McGrath D, Poole DBR, Fleming GA, Sinnott J (1982} Ir J Agric Res 21:135-145 Morgan JE, Morgan AJ (1988} Environ Pollut 54:123-138 Nelson WC, Lykin8 MH, Mackay J, Newill VA, Finklea JF, H~umner DI (1973} J Chron Dis 26:105-118 Peryea FJ (1991a) Soll Scl Soc Am J 55(5):1301-1306 Peryea FJ (1991b)
"Bior@m@dlation of Lead Arsenate-Contamlnated Soils", US Dept Interior Grant
No. G1597-03, Water Research Center Project No. A-168-WASH,
30 pages
sheppard SC (1992) Water, Air, sol1 Pollut 54:539-550 Snedecor, GW, Cochran WG (1980} Statistical Methods,
7th ed. Section 18.9.
Iowa State Univ
Press, Ames, pp. 385-388 van Wijnen JH, Clausing P, Brunekreef B (1990} Environ Re8 51:147-162 Vandacaveye SC, Horner GM, Keaton CM (1936} Soil Scl 42:203-215 Veneman PLM, Bodine SM, Murray JR, Baker JH (1982) Coamun in Soll Sci Plant Anal 13(8}:585-592 Veneman PLM, Murray JR, Baker JH (1983) J Environ Qual 12(1):101-104