G.J. Olson Gordon A. McFeters S.C. Turbak Roger W. Lee William S. Dockins 1980 <p><span>Ground water in southeastern Montana was investigated to determine if </span><span>sulfide production was bacterially mediated. </span><span>Sulfate—reducing bacteria were </span><span>detected in 25 of 26 ground—water samples in numbers ranging from 2.0 x 10</span>^{<span>1 </span>}<span>to greater than 2.4 x 10</span>^{<span>4 </span>}<span>bacteria per 100 milliliters. Stable sulfur isotope </span><span>fractionation studies indicate a biological role in sulfate reduction. However, </span><span>sulfate—reducing activity as determined by use of a radioactive sulfur isotope </span><span>was observed in only 1 of 16 samples. Bacterial dissimilatory sulfate reduction </span><span>is postulated to be responsible for a major part of the sulfide produced in </span><span>these ground waters. These bacteria are most likely active in the adsorbed </span><span>state, possibly in subsurface microzones where environmental conditions are </span><span>conducive to sulfate reduction.</span></p> application/pdf 10.3133/wri809 en U.S. Geological Survey Sulfate reduction in ground water of southeastern Montana reports