Physical characteristics of salt marsh sediments: ecological implications

Abstract

We measured the physical charactenstics of 4 sedlment types commonly found in southeastern (USA) salt marshes and their relationship to sediment drainage and compressibility. Compressibility was found to be positively correlated with total silt-clay content (r2 = 0.953) and negatively correlated with total sand content (r2 = 0.942). A linear relationship (r2 = 0.832) was found between the square root of sediment percolation velocity and bulk density. Calculations of the rate of air entry and porewater turnover based on our measurements of drainage and compressibility are consi-stent with the supply of SO,' ' necessary to support the rates of SO,'-reduction found at North Inlet, South Carolina, USA, by previous researchers and indicate that compressibility may regulate the turnover of reduced end products such as pyrite. For incompressible sediments, it was demonstrated that the entry of air into sediments following water loss by evapotranspiration is quantitatively important in oxidizing reduced sulfur compounds, while drainage of compressible creek bank sedi-ments is apparently sufficient to replace SO4'-utilized by dissimilatory Sod2-reducers.