SELENIUM IN THICK SPIKE WHEATGRASS AND YELLOW SWEET CLOVER GROWN ON SLUDGE-AMENDED ALKALINE MINE BACKFILL

Plant uptake of selenium (Se) on western United States mine lands is a concern in reclamation efforts due to the potential growth of vegetat ion that may be considered toxic to wildlife and domestic animals if c onsumed over time. A study was designed to determine if sewage sludge from Rock Springs and Kemmerer/Evanston, Wyoming, at rates of 25, 50, and 100 Mg/ha, would enhance or decrease Se uptake by yellow sweet clo ver (Melilotus officinalis) and thick spike wheatgrass (Agropyron dasy stachyum) grown on mine backfill material (i.e., overburden material t hat has been displaced). Results indicated that increased sludge amend ments significantly decreased plant Se levels. Changes in backfill che mical and physical characteristics were believed to have caused a redu ction in Se bioavailability (as determined by AB-DTPA extraction), eve n though total Se concentrations of the sludge-amended backfill treatm ents were greater with increasing sewage sludge additions. Land applic ation of sewage sludge is therefore recommended as a viable method for mine land reclamation efforts.