| Abstract: | Data are presented for the first systematic measurements of biogenic sulfur gas flux from the major soil orders within the eastern and southeastern United States. Sulfur flux samples were collected and analyzed on-site during the fall of 1977, spring and summer of 1978 and summer of 1979. A total of 27 sampling locales in 17 states were examined. Eight additional sites were visited in 1980. At some locales, two to four soils were examined, providing an even broader sampling of the soil orders. Three of the locales were revisited two or three times during the course of the study to establish the influence of seasonal climatology upon the measured emission rates and chemical composition of the sulfur flux mixtures. The sulfur gas enhancement of sulfur-free sweep air passing through dynamic emission flux chambers placed over selected sampling areas was determined by combined cryogenic enrichment sampling and wall-coated, open tubular, capillary column, cryogenic gas chromatography (WCOT/GC) using a sulfur selective, flame photometric detector (FPD). Sulfur gas mixtures varied with soil order, ambient temperature, insolation, soil moisture, cultivation, and vegetative cover. Statistical analyses indicated strong temperature and soil order relationships for sulfur emissions from soils. Fluxes ranged from 0.001 g to 1940 g of total sulfur as S/m2/yr. The calculated mean annual sulfur flux, weighted by soil order, was 0.03 g S/m2/yr for the study land area, or 110,872 metric tons (mT). The estimated annual average sulfur flux increased from 65 mT per 6400 km2 for the land grids in the northernmost east-west grid tier to an average 1800 mT for the land grids in the southern Florida grid tiers. This systematic sampling of major soils provides a much broader data base for estimating biogenic sulfur flux than previously reported for isolated intertidal sites, and presents the first sulfur flux estimates for inland soils which make up approximately 93% of the land of the eastern United States. |
