| Abstract: | ![]()
Nutrient effects on microbial growth and arsenic volatilization from retorted oil shale and soil were evaluated in a laboratory study. Dimethylarsinic acid (DMAA), methanearsonic acid (MAA) and sodium arsenate amendments were used with added nutrients, or with retort process water added to simulate possible co-disposal conditions. In experiments with soil and retorted shale, dimethylarsinic acid showing the highest cumulative arsenic releases, in comparison with added inorganic sodium arsenate (SA). Low but detectable amounts of innate arsenic present in retorted shale could be volatilized with added organic matter. In soil, arsenic volatilization showed a direct relationship to nutrient levels and microbial growth. With shale, in comparison, a threshold response to available nutrients was evident. Distinct increases in fungal community development occurred with nutrients available at a level of 2.5% w/v, which also allowed incresed arsenic volatization. Codisposal of retort process waters with shale allowed arsenic volatilization without the addition of other nutrients. The presence of retort process water limited arsenic volatilization from the added organometallic compounds DMAA and MAA, but not from SA or innate arsenic. These differences should be useful in the definition of permissive and non-permissive environmental conditions for arsenic volatilization in bioremediation programs. |
