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The Newark Bay Estuary in northern New Jersey contains one of the largest urban wetland complexes in the United States, but the majority of the wetlands and habitats have been lost due to urbanization and industrialization. Field and laboratory research was conducted to understand the impacts of human activities on the biogeochemistry of nutrients and heavy metals in the urban estuary. Concentrations of dissolved nutrients such as nitrate, ammonia, and phosphate were higher in the Hackensack River than in the Passaic River or the Newark Bay, while the Hackensack River was more deficient in dissolved oxygen. Sediment oxygen demand and mobilization of nutrients were higher in sediments with higher organic matter content as a result of microbial decomposition of organic matter. Heavy metals (Cr, Cu, Pb, and Zn) and organic matter were more enriched in finer sediment grains such as silt and clay. There were positive correlations among heavy metals as well as organic matter in sediments. The results suggest that fine grained sediments, which can be readily suspended and transported during tidal cycles, may play a significant role in biogeochemical cycling of nutrients and heavy metals in the urban estuary. It appears that the current sources of nutrients and heavy metals in the water and sediment of the Newark Bay Estuary are mainly domestic effluents from sewage treatment plants during non-storm periods as well as combined sewer overflows during storm events, but further research including more frequent and pervasive water and sediment quality monitoring during dry and wet periods is needed. Full article

A conceptual site model (CSM) has been developed for the Newark Bay Study Area (NBSA) as part of the Remedial Investigation/Feasibility Study (RI/FS) for this New Jersey site. The CSM is an evolving document that describes the influence of physical, chemical and biological processes on contaminant fate and transport. The CSM is initiated at the start of a project, updated during site activities, and used to inform sampling and remediation planning. This paper describes the hydrodynamic and sediment transport components of the CSM for the NBSA. Hydrodynamic processes are influenced by freshwater inflows, astronomical forcing through two tidal straits, meteorological conditions, and anthropogenic activities such as navigational dredging. Sediment dynamics are driven by hydrodynamics, waves, sediment loading from freshwater sources and the tidal straits, sediment size gradation, sediment bed properties, and particle-to-particle interactions. Cohesive sediment transport is governed by advection, dispersion, aggregation, settling, consolidation, and erosion. Noncohesive sediment transport is governed by advection, dispersion, settling, armoring, and transport in suspension and along the bed. The CSM will inform the development and application of a numerical model that accounts for all key variables to adequately describe the NBSA’s historical, current, and future physical conditions. Full article