Tuesday, November 6, 2007
227-4
Variability in Colloid Elution and Metal Transport in Reclaimed Soils Following Coal Mining.
Jarrod Miller1, A.D. Karathanasis1, Ole Wendroth2, and Christopher Matocha3. (1) University of Kentucky, 356 S. Broadway Park, Lexington, KY 40504, (2) N-122M Ag Science N., University of Kentucky, University of Kentucky, Department of Plant & Soil Science, Lexington, KY 40546-0091, (3) N-122R Ag Sci Ctr N, University of Kentucky, University of Kentucky, Agronomy Dept., Lexington, KY 40546-0091
Soils disturbed by strip mining practices may have increased colloid loads moving to groundwater resources. Enhanced colloid movement may also increase the transport of contaminants into our water resources. Two sites were chosen for this study, a 30 year old reclaimed strip mine in southwest Virginia and a recently mined area from eastern Kentucky. 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. Biosolids were added to an additional reclaimed monolith treatment at a rate of 20 T/Acre. Leaching experiments with de-ionized water at a rate of 1.0 cm/h involved 6 cycles of 8 hours each, giving each monolith at least 2 pore volumes of leaching. Native soil monoliths from Virginia had an average colloid elution of 857 mg over all cycles, compared to 1460 mg for the reclaimed and 76 mg for the reclaimed plus spoil material, respectively. When the reclaimed soil monoliths with the spoil material were amended with biosolids colloid elution increased to 870 mg. After drying, Virginia native soil monoliths eluted an additional 2315 mg, while reclaimed soil monoliths eluted an additional 1618 mg of colloids. Native soil monoliths from eastern Kentucky averaged 7269 mg of colloid elution, compared to 10,935 mg for the reclaimed and 0 for the reclaimed plus spoil material, respectively. The fractional metal load (Cu, Cr, Cd, Zn, Ni, or Pb) bound to the colloids eluted from the Virginia monoliths averaged 13% for the native, 62% for the reclaimed, 9% for the reclaimed with spoil, and 84% for the reclaimed plus spoil material amended with biosolids. The respective fractional metal loads for the eastern Kentucky monoliths were 52% for the native and 12% for the reclaimed. Zinc and Cu loads were consistently higher in all eluents.