RAPID TOLUENE MINERALIZATION BY AQUIFER MICROORGANISMS AT ADAK, ALASKA - IMPLICATIONS FOR INTRINSIC BIOREMEDIATION IN COLD ENVIRONMENTS

Sediments from a relatively cold (5 degrees C), petroleum hydrocarbon-contaminated aquifer in Adak, AK, mineralized [C-14]toluene at an aerobic rate (16.3% day(-1) at 5 degrees C) comparable to that (5.1% day(-1) at 20 degrees C) of sediments from a more temperate aquifer at Hanahan, SC. In addition, rates of overall microbial metabolism in sediments from the two aquifers, as estimated by [1-C-14]acetate mineralization, were similar (similar to 10.6% h(-1)) at their respective in situ temperatures. These results are not consistent with the common assumption that biodegradation rates in cold groundwater systems are depressed relative to more temperate systems. Furthermore,these results suggest that intrinsic bioremediation of petroleum hydrocarbon contaminants in cold groundwater systems may be technically feasible, in some cases.