Реферат: There are two prominent theories for the source of nitrate in cave saltpeter: animal wastes such as bat
guano, and groundwater seepage. While it has been shown that the seepage theory works well for the
saltpeter caves of the southeastern US, the other model works best for guano caves in the southwestern
U.S. We used a dual isotope/geochemical approach to study the origin of nitrate-rich sediments from
caves, crevices, and rockshelters in Minnesota and Illinois, comparing them with samples collected from
Great Saltpetre Cave in Kentucky. The dual isotope approach analyzes both the δ15N and δ18O in the
nitrate ion. In such an analysis, nitrates deriving from animal wastes can be distinguished from those
derived by nitrification of organic matter in the soil. While there is some overlap, the isotopic results
suggest that some of the nitrates from Minnesota caves derive from animal waste, while other nitrate