| The oxidation of pyritic mine spoil generates copious amounts of acid resulting in extensive environmental degradation. Pyrite oxidation and reclamation of pyritic mine spoil were characterized by measurement of pH, reduced sulfur compounds, sulfate and total soluble iron. Various applied complex organic compounds were evaluated as inhibitors of pH decline. Successful compounds were studied in detail regarding mechanisms of inhibition. The sulfur oxidation intermediates thiosulfate, trithionate and tetrathionate were detected in the untreated spoil at all times over the 28-day incubation period. Iron oxidation was found to be more critical than sulfur oxidation to total acid production. Application of organic amendments to the spoil limited acid production via iron immobilization or by inhibiting the activity of the spoil microflora. Using a fluorescence quenching titration technique, conditional stability constants were determined for a water-soluble organic compound reacted with both ferrous and ferric iron. The contribution of the organic compound to oxidation/reduction of iron and possible concurrent acid production from pyritic spoils was also studied. A field study was conducted in Southeastern Ohio to examine the ability of various municipal and industrial wastes to effectively reclaim a toxic mine spoil. Plots amended with topsoil, sewage sludge and the high rate of composted papermill sludge consistently maintained optimum pH levels, and topsoil-amended plots were lowest of all treatments in aluminum and iron. Powerplant fly ash-amended plots were associated with lowest pH and were among the highest in aluminum content. Vegetative dry matter yields decreased sharply over the study period for each amendment. By the final year of study, topsoil plots had the highest dry matter yields over all treatments. |
