Emission Survey of Biogenic Sulfur Flux from Terrestrial Surfaces

The most critical gap in knowledge important for delineating the global atmospheric cycle of sulfur is uncertainty about the magnitude, distribution, source, and form of biogenic emissions to the atmosphere. All global sulfur budget estimates which have appeared recently in the literature require a substantial biogenic sulfur emission to balance the budget; however, the estimated magnitude of the global natural source strengths vary widely—from ∼35 to ∼280 TgS/yr. Direct measurements of sulfur emission rates were made by sampling various terrestial surfaces (water surfaces, soil, and selected vegetation) during 1978. An emission flux reactor (chamber) technique was used to determine the emission rates of sulfur compounds into the atmosphere. The sulfur gases were identified and their concentrations in the flux reactor measured with a gas chromatograph equipped with a flame photometric detector specific for S. H2S (average flux ∼0.5 gS/m2/yr), (CH3)2S (average flux ∼0.4 gS/m2/yr), COS (average flux ∼0.03 g...