Year of Publication

2008

Degree Name

Doctor of Philosophy (PhD)

Document Type

Dissertation

College

Agriculture

Department

Soil Science

First Advisor

Dr. A.D. Karathanasis

Abstract

Soils disturbed by strip mining practices may have increased colloid loads moving to groundwater resources, also enhancing the transport of contaminants into our water resources. We hypothesize that contaminant transport within soils following mining is enhanced by colloid mobility. 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 at a rate of 20 T/acre. Leaching experiments with deionized 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, reclaimed soil monoliths had an elution of 1460 mg, reclaimed soil monoliths with spoil material had a colloid elution of 76 mg, and when biosolids were amended to reclaimed soil and spoil monoliths, 870 mg colloids were eluted. Native soil monoliths from eastern Kentucky eluted 7269 mg colloids, reclaimed monoliths from eastern Kentucky eluted 10,935 mg colloids, and reclaimed soils with spoil material eluted no colloids. Lime stabilized biosolids enhanced colloid elution due to high pH dispersing material within the monoliths, while spoil materials with high density and salt content reduced colloid elution. Metal loads in solution were mobilized by DOC, particularly in low sulfate environments, while colloid bound metals increased the total metal loads in the order of Pb > Ni > Cu > Cd > Zn > Cr.

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