Louisiana marsh soils

FIGURE 11.2 Organic sulfur constituents in Louisiana marsh soils, present as acid-volatile sulfides (AVS) elemental sulfur (S ) pyrite (FeSj), and HCl-soluble forms. (Modified from Krairapanond et al., 1992.)... 

Sulfate Reduction Rates in Louisiana Marsh Soils... 

Potential sulfate reduction rates for three Louisiana marsh soils of varying salinities (salt, brackish, and freshwater) have been determined (DeLanne et al., 2002a). The three Louisiana marshes represent different physiochemical environments. The fresh and brackish marsh soils are composed predominantly of organic matter, whereas the salt marsh soils are higher in mineral matter. Sulfate content is higher in the salt marsh. 

Comparison of Potential Sulfate Reduction Rates for Louisiana Marsh Soil to Other Wetland Sites... 

What are the dominant sulfur forms found in Louisiana marsh soils ... 

DeLaune, R. D., I. Devai, C. R. Crozier, and P. Kelle. 2002a. Sulfate reduction in Louisiana marsh soils of varying salinities. Commun. Soil Sci. Plant Anal. 33 79-94. 

Devai I, Delaune RD. 1995. Evidence for phosphine production and emission from Louisiana and Florida marsh soils. Organic Geochemistry 23 277-279. 

DeLaune, R., Buresh, R., and Patrick, W. (1979). Relationship of soil properties to standing crop biomass of Spartina alternflora in a Louisiana marsh. ECMS 8, 477—487. 

Brannon, J. M. (1973). Seasonal variation of nutrients and physiochemical properties in the salt marsh soils of Barataria Bay, Louisiana. M.S. Thesis, Louisiana State University, Baton Rouge. 

In Louisiana coastal marsh soils, inorganic sulfur constitutes 13-30% of the total sulfur pool, with HCl-soluble sulfur representing 78-86% of the inorganic sulfur fraction in freshwater, brackish, and salt marsh (Pezeshki et al., 1991 Krairapanond et al., 1992). AVS accounted for <1% of the total sulfur pool. Pyrite sulfur and elemental sulfur together accounts for 8-33% of the inorganic sulfur pool (Krairapanond et al., 1992). 

Rates of S Accumulation in the Louisiana Barataria Basin Marsh Soils (Mean SE, A/ = 15)... 

FIGURE 14.19 Relationship between hulk density and soil organic carbon content in Louisiana coastal marsh soil. (Data from Hatton et ah, 1983.)... 

Soil mineral matter consists of 50-90% of the dry weight of marsh soils (Nyman et al., 1990). Storm passage including hurricanes is a primary mechanism that delivers mineral sediments to Louisiana marshes (Reed, 1989 Roberts et al., 1989 Turner et al., 2006). Increased water levels and wave action in bays and lakes prior to frontal passage transport sediments from water bottoms to... 

Saltwater intrnsion is a dominant edaphic factor that inflnences the survival, growth, and species composition in coastal wetlands along the Louisiana Gnlf Coast. The net effect of sublethal salt stress is the redaction in growth especially in marsh soils with low bulk density or mineral content in the soil profile. For most species growing in salt and brackish marshes, elevated salinity does not create a favorable environment for growth and productivity (Figure 18.14). In fact, numerous... 

Much of the wetland loss occurring in coastal Louisiana is due to the deterioration of highly organic marsh soil. As discussed earlier, conversion of coastal marshes to inland open water is associated with plant stresses such as saltwater intrusion into nonsaline marshes and increased soil waterlogging as a result of subsidence. Marsh elevation decreases rapidly following plant mortality because of the structural collapse of the living root networks (DeLaune et al., 1994). The peat collapse and the associated erosion result in the conversion of marsh into open water. Conversions to open water system releases a considerable amount of carbon into the estuary where it is either decomposed or... 

DeLaune, R. D., W. H. Patrick, Jr., and J. Brannon. 1976. Nutrient Transformation in Louisiana Salt Marsh Soils. Louisiana State University, Sea Grant Publication. LSU-T-76-009, Center for Wetland Resonrces, Louisiana State University, Baton Rouge, LA. 

Krairapanond, N., R. D. DeLaune, and W. H. Patrick, Jr. 1992. Distribution of organic and reduced sulfur forms in marsh soils of coastal Louisiana. Org. Geochem. 18(4) 489-500. 

R.P. Courtemanche, M.W. Hester, and LA. Mendelssohn, Recovery of a Louisiana Barrier Island Marsh Plant Community Following Extensive Hurricane-induced Overwash, J. Coastal Res. 15(4), 872-883, Fall (1999). G. Singh, H. Singh, and P.P. Bhojvaid, Amelioration of Sodic Soils by Trees for Wheat and Oat Production, Land Degrad. Devel. 9(5), 453 62, Sept.-Oct. (1998). 

FIGURE 18.7 Relationship between soil bulk density and aboveground biomass of the Louisiana saline coastal marsh supporting the species Spartina alterniflora. (Adapted from DeLaune et ah, 1990b.)... 

For stable soil-plant system, nitrogen gains and losses are nearly balanced in the Louisiana Gulf Coast salt marshes (Table 18.9). Nitrogen-rich sediment being deposited on the marsh is the pri-... 

The amounts and profile distribution of various sulfur forms in Louisiana coastal marshes are important in understanding sulfur cycling as related to the origin and type of tidal wetland marshes. Sulfur forms and distribution were determined in P. hemitomon freshwater marsh, a S. patens brackish marsh, and a S. alterniflora salt marsh along a salinity gradient in Barataria Basin, Louisiana. Soil samples were fractionated into acid volatile sulfur (AVS), elemental sulfur, HCl-soluble sulfur, pyrite sulfur, ester sulfate sulfur, carbon-bonded sulfur, and total sulfur (see Chapter 11 for details). 

---