Sulfur wetlands

Nutrients incorporated into herbaceous material are deposited on soil surface or exported from the wetland as detritus or dissolved nutrients released by decaying vegetation. Air-water exchange also plays an important role in biogeochemical cycling of carbon, nitrogen, and sulfur. Wetlands emit methane, carbon dioxide, nitrous oxide, and reduced sulfur gases to the atmosphere. 

R. W. Howarth, J. W. Stewart, and M. V. Ivanov, Sulfur Cjcling on the Continents Wetlands, Terrestrial Ecosjstems and Associated WaterBodies, Scientific Committee on Problems of the Environment Series, John Wiley Sons, Inc., New York, 1992. 

Choi, J.H., Park, S.S., and Jaffe, P.R., The effect of emergent macrophytes on the dynamics of sulfur species and trace metals in wetland sediments, Environmental Pollution, 140, 286-293, 2006. 

Little snlfnr is re-emitted from wetlands into the atmosphere. Table 8.7 gives estimates of global emissions of volatile sulfur compounds from different sources. Total emissions are in the range 98 to 120 Tg (S) year 75 % is anthropogenic, mainly from fossil fnel combustion in the northern hemisphere. The main natural sources are the oceans and volcanoes. Wetlands and soils contribnte less than 3 % of the total emission. 

Howarth RW, Stewart JWB, Ivanov MV. 1992. Sulfur Cycling on the Continents Wetlands, Terrestrial Ecosystems and Associated Water Bodies. Chichester WUey. 

Jokic, A., Cutler, J. N., Ponomarenko, E., van der Kamp, G., and Anderson, D. W. (2003). Organic carbon and sulfur compounds in wetland soils Insights on structure and transformation processes using K-edge XANES and NMR spectroscopy. Geochim. Cosmo-chim. Acta. 67, 2585-2597. 

There are a number of factors which affect the emission rates of biogenic sulfur from wetlands. In a recent study these have been investigated for wetlands in Florida, USA, 157-59) and are summarized in a chapter in this volume (60). These factors are divided into spatial, seasonal, diel and tidal components. In addition, other variables which affect emissions are temperature, insolation, and soil inundation. When these factors are taken into account in estimating emissions, and emission rates are obtained by integrating over the appropriate cycle, the emission estimates are up to two orders of magnitude lower than earlier estimates. However, using these methods results in large uncertainties in the emission estimates, and considerable additional data are required to better refine and extend emission estimates to other environments. 

Lower terrestrial and coastal emission estimates combined with the increasing loss in wetlands 165-681. although it may not significantly impact the global sulfur cycle, may be an important consideration in local contributions of natural emissions to acid precipitation. 

Three areas of uncertainty in this present inventory of natural sulfur emissions which need further work include natural variability in complicated wetland regions, differences in emission rates in the corrected SURE data and those reported by Lamb et al. (1) and Goldan et al. (21) for inland soil sites, and biomass emissions for which only a very limited data base easts. The current difficulty in determining the sources of variability emphasizes the need to better understand natural sulfur release mechanisms. At present, it may be useful to consider the emission rates based on the corrected SURE data as an upper bound to natural emissions and use the emission rates based on data described by Lamb et al. (1) as a more conservative estimate of natural sulfur emissions. However, this still leaves a factor of 22 difference between the suggested upper bound and our best current estimate. 

Variability in Biogenic Sulfur Emissions from Florida Wetlands... 

Coastal wetlands have long been noted for their relatively high emission of volatile sulfur gases to the atmosphere indeed the typical odor of marshes often is due largely to DMS. Several studies have reported emissions of DMS, H2S, and other sulfur compounds, dimethyldisulfide, carbonyl sulfide, and carbon disulfide (10-12.40-42). DMS and H2S constitute the bulk of the flux, with DMS predominating in vegetated areas and H2S in mud flats. Fluxes of DMS... 

Stribling, J. M., and Cornwell, J. C. (2001). Nitrogen, phosphorus, and sulfur dynamics in a low salinity marsh system dominated by Spartina alternijlora. Wetlands 21, 629—638. 

Cohen A. D. (1984) The Okeefenokee Swamp a low-sulfur end-member of a shoreline-related depositional model for coastal plain coals. In The Okeefenokee Swamp Its Natural History, Geology, and Geochemistry (eds. A. D. Cohen, D. J. Casagrande, M. J. Andrejko, and G. R. Best). Wetland Surveys, Las Alamos, NM, pp. 668-680. 

Human activity has substantially increased the hydrologic import of oxidized nitrogen and sulfur into wetland ecosystems. Emissions of sulfur are expected to double over the next 50 years (Rodhe,... 

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