Saturday, 15 July 2006

Colloid Mobilization and Heavy Metal Transport in Reclaimed Soils Following Coal Mining.

Jarrod Miller1, Anastasios Karathanasis1, and Ole Wendroth2. (1) Univ of Kentucky, Dept of Plant and Soil Sciences, 500 South Limestone, Lexington, KY 40504, (2) Univ of Kentucky, Dept of Plant and Soil Sciences, N-122M Agr. Sci. North, Lexington, KY 40546

Reclaimed soils following strip mining can accentuate colloid elution by disturbance of soil and geological strata as well as biosolid amendment applications. Heavy metal transport may be enhanced by weathering spoil material, biosolid applications and colloid transport. Two sites were chosen for this study, one in the Appalachian region of southwest Virginia and one in the eastern Kentucky coal fields, to observe colloid transport under simulated rainfall conditions. 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 6 hours each, with intermittent surface drying between cycles via an electric fan. Native Virginia soil monoliths had an average colloid elution of 857 mg over all six cycles, disturbed soil monoliths had an elution of 1460 mg, and reclaimed soil monoliths with spoil material had a colloid elution of 76 mg. Spikes in pH and EC between cylces suggest that some treatments may have varying pores contributing to transport. Reclaimed eastern Kentucky soils are recently deposited in comparison and may conduct colloids and metals through different preferential pathways than the 30 year old Virginia monoliths. The results suggest significant increases in colloid generation following soil disturbance that could induce heavy metal transport and further groundwater quality deterioration.

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