The primary objective of this study was to determine the salinity effect on nutrient release and the denitrification rate in a sediment-water system. To accomplish this objective, bench-scale microcosm studies of York River sediments and Occoquan Reservoir sediments were conducted. Seawater and freshwater were mixed in various ratios to simulate seasonal, salinity-varying environments in the Chesapeake Bay and its tributary estuaries.

Experiments were conducted under aerobic, anaerobic, and anoxic conditions. The results showed that high salinity can cause flocculation of particles and result in lower concentration of phosphate under aerobic conditions, but the flocculation effect was not obvious under anaerobic conditions. The release of ammonia was governed by the salinity; the increasing salinity accelerated the release of ammonia by ion exchange. The denitrification rate under anoxic conditions in the system was not influenced by the salinity.