Gas Chromotograph/Mass Spectrometer System for the Determination of Atmospheric Sulfur Gases

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A basic objective of current research on the chemistry of the atmosphere is to develop an improved understanding of the fundamental processes responsible for creating and destroying the trace chemical compounds present in the atmosphere. In order to study and understand the chemical, physical and biological processes influencing the composition of the atmosphere it is necessary to investigate and develop improved techniques for measuring the compounds present in the air. The objective of this project is to develop reliable new analytical techniques for studying the cycle of sulfur species through the global troposphere. These techniques have been designed to permit measurement of the concentrations of gaseous species currently thought to be important in the biogeochemical cycling of sulfur, carbon disulfide, through the atmosphere. These species include carbonyl sulfide, carbon disulfide, hydrogen sulfide, dimethyl sulfide, methyl mercaptan, and sulfur dioxide. The marine sulfur cycle is particularly interesting because it may link biological activity in the oceans to climate and cloud formation. Measurements of the concentrations of sulfur species provide data that are important for developing a quantitative understanding of the fluxes and reactions of these sulfur compounds. A technique of gas chromatography/mass spectrometer with isotopically labelled internal standards (GC/MS/ILS) has been developed and laboratory tested under NSF grant ATM-8515000. The instrumentation is capable of real time measurements of sulfur gases and is several times more sensitive than flame photometric detection. Isotopically labelled internal standards have improved precision and accuracy. This research will construct a field deployable (aircraft and ship platforms) instrument and test the performance of the instrument in the field.