Biogeochemical processes in a small California estuary. 1. Benthic fluxes and pore water constituents reflect high nutrient freshwater inputs

organic matter produced in the water column is decomposed and regenerated in sediments (Graf 1992, Kemp et al. 1992, Jrgensen 1996a). Within sediments, cycling of oxygen (O), carbon (C), N, P and sulfur (S) are intertwined as decomposition proceeds. Two electron acceptors that dominate organic C decomposition in sediments are O 2 and SO 4 2 - (Mackin & Swider 1989). At the sediment-water interface, O 2 diffuses into sediments from the water column and aerobic processes such as aerobic respiration (estimated as sediment O 2 consumption, SOC) dominate. Once O 2 is