Tuesday, November 14, 2006

Effect of Salinity and Sediments on Carbon Gas Emissions in Wetland Soils.

Jim Wang, Louisiana State University - Agronomy & Environmental Management, 313 M.B. Sturgis Hall, Louisiana State University, Baton Rouge, LA 70803, Syam Dodla, Louisiana State Univ, Dept of Agronomy and Environmental Management, 313 Sturgis Hall, Baton Rouge, LA 70803, and Ronald DeLaune, Wetland Biogechemistry Inst, Louisiana State Univ, Baton Rouge, LA 70803-7511.

Understanding factors influencing carbon gas emissions is necessary to characterize carbon cycles in coastal wetland systems. In this study, effects of salinity and sediment on carbon gas emissions in three Louisiana wetland soils were investigated.  Soil samples of from woody swamp, fresh, and saline marshes were collected. Freshwater marsh and swamp samples were then treated with different levels of salinity with composition similar to sea waters, and freshwater and saline marsh samples were treated with a common soil clay. All treatments were carried out in an open container and the carbon gas mission was monitored periodically for one year. Increasing salinity decreased carbon gas emission from freshwater marsh soil but had little effect on woody swamp soil.  Increasing clay concentration decreased CO2 emission from the freshwater marsh soil however this effect was significant only in the presence of elevated Ca concentration. Additions of Ca and K ions as chloride salts alone did not affect either CO2 or CH4 emissions from the freshwater marsh soil.  The latter treatment did, however, increase significantly CO2 emissions from swamp soil.