A Model for the Evaluation and Management of Contaminants of ...

VII.
Tier-1 Modeling Tasks
As noted above, the overall goal of the Tier-1 modeling effort will be to develop priorities
for contaminant reduction actions, update the DMMP, and to assist the Port Authority in
future Water Resources Development Act planning. Towards these objectives, the
following modeling tasks are requested:
Task 1-1: The first task will be to select a large-space-scale, seasonal-time-scale model(s)
for contaminant fate, transport and bioaccumulation. It is envisioned that three
formulations of existing models will be further refined and developed for
hydrophobic organics, inorganic metals and mercury. The proposed Tier-1
modeling can either build upon the Thomann-Farley Model (WASTOX; Connolly,
1991; Connolly and Thomann, 1985), or it can recommend other appropriate
models. In either case, a full justification for selection should be given in the
proposal.
Simulated fate and transport processes for the water column should include
effects of advection, dispersion, external sources, settling, resuspension, bed
diffusion, volatilization and aerobic degradation. Likewise, coupled sub-models
for the sediment layers should compute variations in sediment contaminant
concentrations due to settling, resuspension, burial, transformations, sedimentwater
column diffusion, and diffusive exchange with deep sediments. In
modeling the hydrophobic organic contaminants of concern, chemical
partitioning between freely dissolved and particulate phases may be assumed to
be functions of the fraction of organic carbon on the solids and the octanol-water
partitioning coefficient (Karickhoff, 1981). PCBs should be modeled as PCB
homologue groups or other congener groupings rather than total PCBs. The
modeling and data analysis, however, must be capable of resolving PCB
predictions into total PCB concentrations to be compared with existing
endpoints.
The modeling framework should include either a bioconcentration factor or,
preferably, a coupled food-chain model to calculate the accumulation of
contaminants in biota. The various species being collected and monitored for
contaminant levels are listed in Table 5. The model(s) must be capable of
predicting concentrations of the primary contaminants of concern (i.e., PCBs,
dioxin, PAHs, DDT, cadmium, mercury and chlordane) in polychaete worms
(Nereis sp., or an appropriate surrogate) and clams (Macoma sp., or
appropriate surrogate). Biota-Sediment-Accumulation-Factors (BSAFs) may
be employed for calculating contaminant concentrations in these dredgedmaterial
test organisms. The model(s) must also be capable of evaluating and
predicting uptake of the primary contaminants in up to four higher trophic level
species (striped bass, white perch, American eel and blue crab). Proposers
must discuss the limitations in knowledge for modeling all four species, and
recommend which species can be readily modeled to provide the most
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