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ABSTRACT
Field and greenhouse experiments were performed to assess the performance of phytoremediation of arsenic and lead from contaminated soil at an EPA Superfund site (Barber Orchard). Chinese Brake ferns (Pteris vittata) were used to extract arsenic. On average, fern shoot arsenic concentrations were as high as 20 times the soil arsenic concentrations under field conditions. It was estimated that 8 years would be required to reduce the acid-extractable portion of soil arsenic to safe levels (40 mg/kg). The effect of soil pH on arsenic extraction was also investigated. Results indicate that increasing soil pH may improve arsenic removal. Indian mustard plants (Brassica juncea) were used under greenhouse conditions to phytoextract soil lead. EDTA was applied to soil and was found to improve lead extraction. When the EDTA concentration was 10 mmol EDTA/kg soil in soil containing 338 mg Pb/kg soil, mustard plants extracted approximately 32 mg of lead. In conclusion, phytoremediation would be a suitable alternative to conventional remediation techniques, especially for soils that do not require immediate remediation.
KEY WORDS: arsenic, lead, phytoremediation, brake fern, indian mustard, EDTA.
I. INTRODUCTON
Arsenic is a ubiquitous element that poses a serious threat to human health. It is a naturally occurring contaminant, released through geological weathering, and is anthropogenically magnified through the environment due to its use as a pesticide, wood preservative, and as an artifact of valuable metal ores. In October 2001, the EPA reduced the Maximum Contaminant Level of As in drinking water to 10 (mu)g/L to reduce potential As-related illnesses. It has been reported that soil arsenic concentrations above 40 mg/kg may cause toxicological risks, especially in children (Dudka and Miller, 1999). Arsenic is carcinogenic (either directly or indirectly (Mass, 2001)), an endocrine disruptor, and is linked to a variety of other abnormalities (Iffland, 1994). Arsenic exists in nontoxic forms such as: metallic arsenic, metal arsenides and sulfidic compounds (Iffland, 1994). Arsenic also exists in many toxic inorganic and organic forms as both As (III) and As (V). Arsenic in the form of arsenates (AsO^sub 4^^sup 3-^) was historically used as a pesticide for grape plants, orchards, and cotton. Chromated copper arsenate is utilized in wood treatment. Roxarsone (3-nitro4-hydroxyphenyl arsonic acid) is employed in chicken farming as a weight gain...