0221880 Silverstein The effects of acid mine drainage on natural biogeochemical nitrogen cycling will be studied with respect to the interaction of microbial nitrogen and iron transformations at the lowered pH found in receiving waters. Competition between ferric iron and nitrate as electron acceptors, use of ferrous iron as electron donor in denitrification, and mobilization of iron and other heavy metals from bacterial reduction will be investigated in acid main drainage impacted streams. Species identification in impacted and unimpacted streams will be made utilizing DNA probes and the FISH technique and microscopic counts will be used to produce quantitative estimates of chemolithotrophic iron oxidizers and heterotrophic acidophiles.
