Fate and Transport Modeling of Sediment Contaminants in the New York/New Jersey Harbor Estuary

摘要

Sediment contamination in the New York/New Jersey Harbor estuary hasadversely impacted both the disposal costs and the disposal options for material dredgedfrom the Harbor. In response to this problem, the Port Authority of New York and NewJersey and several state agencies, through a bi-state dredging agreement, formed theContamination Assessment and Reduction Program (CARP). One aspect of CARP wasthe development of a series of numerical models that serve as both diagnostic andpredictive tools. The CARP numerical models include hydrodynamic, sediment transport,organic carbon production, contaminant fate and transport, and bioaccumulation models.These models account for the causal link between external sources of contaminants, suchas tributary headwaters, sewage treatment plants, urban runoff, combined sewer overflow,atmospheric deposition, and landfill leachate, to ambient concentrations of multiplecontaminant classes in water, sediment, and biota of the Harbor. The contaminant classesconsidered include PCBs, dioxin/furans with 2,3,7,8 substitutions, organochlorinepesticides related to DDT and chlordane, PAHs, and the metals cadmium, mercury, andmethyl mercury. After several years of development and calibration, the CARP modelsnow diagnose how much of observed Harbor contamination results from current loadingsversus legacy contamination still remaining in the system. Further, the CARP modelshave been used to forecast expected future contamination levels achievable throughnatural attenuation and a combination of natural attenuation and various reductions ofcurrent loadings and/or removal and remediation of in-place sediments. The modelingapproach and application applied under CARP serves as an excellent case study for otherurban estuaries and ports. Although developed specifically for the New York/New JerseyHarbor, the CARP model kinetic formulations are easily transferable to other systems.Some of the novel features of the CARP model include mechanistic mercury methylationkinetics and the inclusion of a eutrophication model.