The objective of this study was to estimate the magnitude of biogenic sulfur emissions from the northeastern United States - defined as the EPRI Sulfate Regional Experiment (SURE) study area. Initial laboratory efforts developed and validated a portable sulfur sampling system and a sensitive, gas chromatographic analytical detection system. Twenty-one separate sites were visited in 1977 to obtain a representative sulfur emission sampling of soil orders, suborders, and wetlands. The procedure determined the quantity of sulfur added to sulfur-free sweep air by the soil flux as the clean air was blown through the dynamic enclosure set over the selected sampling area. This study represents the first systematic sampling for biogenic sulfur over such a wide range of soils and such a large land area. The major impacts upon the measured sulfur flux were found to include soil orders, temperature, sunlight intensity, tidal effects along coastal areas. A mathematical model was developed for biogenic sulfur emissions which related these field variables to the mean seasonal and annual ambient temperatures regimes for each SURE grid and the percentage of each soil order within each grid. This model showed that at least 53,500 metric tons (MT) of biogenic sulfur are emitted from themore » SURE land surfaces and approximately 10,000 MT are emitted from the oceanic fraction of the SURE grids. This equates to a land sulfur flux of nearly 0.02 gram of sulfur per square meter per yr, or about 0.6% of the reported anthropogenic emissions withn the SURE study area. Based upon these data and the summertime Bermuda high clockwise circulation of maritime air across Florida and the Gulf Coast states northward through the SURE area, the total land biogenic sulfur emission contribution to the SURE area atmospheric sulfur burden might approach 1 to 2.5% of the anthropogenic.« less