Diagenetic processes near the sediment- water interface of Long Island Sound. I. Decomposition and nutrient element geochemistry (S, N, P).

Pore-water profiles of SO₄^2-, alkalinity, HPO₄^2-, and NH₄⁺ in the top 1m of sediment differ radically in different depositional environments of Long Island Sound. Evidence for extensive sulfate reduction and organic matter decomposition is found in shallow water along the N coast; in deeper water the buildup of decomposition products or depletion of SO₄^2- in sediment pore water is greatly lowered. All stations show similar seasonal variation in pore-water profiles near the sediment-water interface. A 2-dimensional transport reaction model incorporating both radial transport into burrows and vertical diffusion is presented. This model is capable of predicting both the form and magnitude of pore-water profiles extraordinarily well at all stations.-after Author