USGS: Speciation and Isotopic Composition of Sulfide and Sulfate Minerals
Michele Tuttle, Paul Briggs, and Cyrus Berry
Sulfur is ubiquitous in the natural geochemical environment. It occurs in sulfide and sulfate minerals, as well as in its elemental state, in ores related to mineral deposits; in thick beds of marine and terrestrial evaporites; in surface and ground water; in organosulfur compounds that comprise all living organisms, and in atmospheric aerosols. These sources are linked to the sulfur cycle through a number of geochemical processes. Understanding these processes, whether natural or anthropogenic, is often key to help unravel environmental issues such as acid-rock drainage, salinization of steams and rivers, attenuation of contaminant plumes in ground water, contamination related to combustion/refining of energy commodities, and climate change.
There are a number of geochemical static and kinetic tests used to understand the processes within a sulfur cycle, whether at a local research site or on a global scale. They include analyzing the amount, species and isotopic composition of sulfur in a snapshot or within a temporal framework. This subtask of the Aqueous Geochemistry Research and Development Project evaluates and develops methods needed to provide the data for the USGS studies that look at the processes within the entire sulfur cycle or in individual reservoirs.