Transfer of Pb and As into vegetables grown on orchard soils historically contaminated by Pb arsenate pesticides was measured in the greenhouse. Lettuce, carrots, green beans, and tomatoes were grown on soils containing a range of total Pb (16.5–915？mg/kg) and As (6.9–211？mg/kg) concentrations. The vegetables were acid-digested and analyzed for total Pb and As using ICP-mass spectrometry. Vegetable contamination was dependent on soil total Pb and As concentrations, pH, and vegetable species. Arsenic concentrations were the highest in lettuce and green beans, lower in carrots, and much lower in tomato fruit. Transfer of Pb into lettuce and beans was generally lower than that of As, and Pb and As were strongly excluded from tomato fruit. Soil metal concentrations as high as 400？mg/kg Pb and 100？mg/kg As produced vegetables with concentrations of Pb and As below the limits of international health standards. 1. Introduction Arsenic (As) and lead (Pb) have been used historically in pesticides (e.g., calcium arsenate, lead arsenate, and copper arsenate) applied to orchard crops such as apples and peaches, as well as to some other crops such as potatoes. Because Pb is quite immobile, and As is only very slowly leached through soils [1, 2], the cumulative contamination of orchard soils by lead and arsenate beginning in the late 1800s persists today . As old orchard lands are converted from agricultural to residential uses, the potential hazard to human health may be increased from certain exposure pathways arising from gardening and direct contact with soil. The scale of this problem is largely based on estimates that millions of acres across North America have been contaminated by arsenic and lead pesticides. Virginia may have 100,000–300,000 acres of old orchard land , and other states with large acreages of impacted orchard land include Washington (188,000 acres), Wisconsin (50,000 acres) and New Jersey (up to 5% of the total agricultural acreage) . The total area of historical soil contamination in New York state is uncertain, but apple production has occupied about 40–50,000 acres in recent decades, with a general long-term decline in orchard acreage and a simultaneous increase in yield. It seems likely, then, that the present apple crop acreage underestimates the total land area that may have been contaminated by As and Pb at some time in the past. The potential transfer of soil Pb and As into vegetable crops is a concern when garden soils are contaminated by these toxic metals. With growing concern about dietary exposure to these two toxic
T. Schooley, M. J. Weaver, D. Mullins, and M. Eick, “The history of lead arsenate use in apple production: comparison of its impact in Virginia with other States,” Journal of Pesticide Safety Education, vol. 10, pp. 22–53, 2008.
D. J. Kenyon, D. C. Elfving, I. S. Pakkala, C. A. Bache, and D. J. Lisk, “Residues of lead and arsenic in crops cultured on old orchard soils,” Bulletin of Environmental Contamination and Toxicology, vol. 22, no. 1, pp. 221–223, 1979.
M. B. McBride, T. Simon, G. Tam, and S. Wharton, “Lead and arsenic uptake by leafy vegetables grown on contaminated soils: effects of mineral and organic amendments,” Water, Air, and Soil Pollution, vol. 224, pp. 1378–1387, 2012.
D. S. Ross and Q. Ketterings, “Recommended methods for determining soil cation exchange capacity,” in Recommended Soil Testing Procedures for the Northeastern United States, Northeastern Regional Publication no. 493, pp. 75–85, 2011.
M. Fleming, Y. Tai, P. Zhuang, and M. B. McBride, “Extractability and bioavailability of Pb and As in historically contaminated orchard soil: effects of compost amendments,” Environmental Pollution, vol. 177, pp. 90–97, 2013.
W. Jiang, S. Zhang, X. Shan, M. Feng, Y. G. Zhu, and R. G. McLaren, “Adsorption of arsenate on soils—part 2: modeling the relationship between adsorption capacity and soil physiochemical properties using 16 Chinese soils,” Environmental Pollution, vol. 138, no. 2, pp. 285–289, 2005.
S. M. I. Huq, J. C. Joardar, S. Parvin, R. Correll, and R. Naidu, “Arsenic contamination in food-chain: transfer of arsenic into food materials through groundwater irrigation,” Journal of Health, Population and Nutrition, vol. 24, no. 3, pp. 305–316, 2006.
E. E. Codling, R. L. Chaney, and C. E. Green, “Lead and arsenic uptake by carrots grown on five orchard soils with history of lead arsenate used,” in Proceedings of the ASA International Meeting Abstracts, p. 241, 2007.
L. Sams？e-Petersen, E. H. Larsen, P. B. Larsen, and P. Bruun, “Uptake of trace elements and PAHs by fruit and vegetables from contaminated soils,” Environmental Science and Technology, vol. 36, no. 14, pp. 3057–3063, 2002.
P. D. Alexander, B. J. Alloway, and A. M. Dourado, “Genotypic variations in the accumulation of Cd, Cu, Pb and Zn exhibited by six commonly grown vegetables,” Environmental Pollution, vol. 144, no. 3, pp. 736–745, 2006.
N. Singh and L. Q. Ma, “Assessing plants for phytoremediation of arsenic-contaminated soils,” in Methods in Biotechnology, Phytoremediation: Methods and Reviews, N. Willey, Ed., vol. 23, pp. 319–347, Humana Press, Totowa, NJ, USA, 2007.
S. Goldberg, S. M. Lesch, D. L. Suarez, and N. T. Basta, “Predicting arsenate adsorption by soils using soil chemical parameters in the constant capacitance model,” Soil Science Society of America Journal, vol. 69, no. 5, pp. 1389–1398, 2005.