Eastern gamagrass uptake of lead and arsenic from lead arsenate contaminated soil amended with lime and phosphorus

Lead arsenate was used in orchards from the 1930s to the 1960s, causing orchard soils to be contaminated with lead and arsenic, which may become an environmental problem when these lands are used for other purposes. Because soil removal is expensive, one alternative is to use plants to remove lead and arsenic from these soils (phytoremediation). Eastern gamagrass [Tripsacum dactlyloides (L.) L.] has an extensive root system and is being used for soil improvement. The objective of this study was to determine uptake of lead and arsenic by eastern gamagrass from lead arsenate-contaminated orchard soils. A noncontaminated soil from Maryland (Typic Paleudults) and orchard soils from Maryland (Oxyaquic Hapludults) and Washington (Aridic Haploxerolls) with total (Aqua Regia extraction) Pb levels of 15, 574, and 943 mg kg(-1) and total As levels of 8, 113, and 194 mg kg(-1), respectively, were used. These three soils were treated with calcium carbonate and potassium phosphate; after incubation for 2 weeks, eastern gamagrass seedlings were transplanted into the amended soils. There was a slight increase in eastern gamagrass dry matter yield with P application compared with the no-phosphorus treatments. Yields were significantly reduced on the Aridic Haploxerolls orchard soil, which had the lowest level of organic carbon and highest levels of Pb and As. There was a slight but insignificant increase in tissue arsenic concentration and a reduction in Pb for plants grown on lime-and P-mended soils. Uptake of Pb was related to soil Pb concentration. Shoot As was related to soil As concentration, but there was no significant difference in root As level between the orchard soils. Eastern gamagrass did not remove substantial amounts of Ph and As from the soils, making this species a poor candidate for phytoremediation of lead arsenate-contaminated soils.