Tuesday, November 14, 2006

Heavy Metal Transport Mediated by Mineral and Organic Colloids in Soils Following Coal Mining.

Jarrod Miller1, Anastasios Karathanasis2, and Ole Wendroth1. (1) Univ of Kentucky, 1973 Trappe Church Rd, Darlington, MD 21034-1426, (2) Univ of Kentucky, Plant and Soil Science Dept, 500 S Limestone St, Lexington, KY 40546-0091

Soils reclaimed after coal mining may have increased concentrations of mineral and organic colloid material. Heavy metal transport may also be enhanced by greater colloid movement. Two sites were chosen for this study, a 30 year old Appalachian strip mine in southwest Virginia and a recently mined area from the eastern Kentucky coal fields. Intact reclaimed soil monoliths were retrieved from sandstone derived soils in southwestern Virginia. Reclaimed monoliths from eastern Kentucky were recreated in the lab. Intact undisturbed (native) soil monoliths representing the soils before mining were also sampled for comparison. Leaching experiments with de-ionized water at a rate of 1.0 cm/h involved 6 cycles of 8 hours each, with intermittent surface drying between cycles via an electric fan. Native soil monoliths from Virginia had an average colloid elution of 857 mg over all cycles, reclaimed soil monoliths had an elution of 1460 mg, and reclaimed soil monoliths with spoil material had a colloid elution of 76 mg. Reclaimed monoliths from eastern Kentucky eluted 10,935 mg colloids. Eluted soluble metals were negligible within the reclaimed Virginia monoliths. Significant metal elution was observed in association with colloids, where colloid bound metal loads increased in the following mg/L sequence: As (0), Cd (1.8), Pb (3.3), Ni (13.0), Cr (14.2), Zn (57.9) and Cu (78.1).