Figure 9. Dredging pathways scenario

sources include precipitation, dissolution, resuspension, sedimentation, diffusion, adsorption, vola-

tilization, decay, and burial as shown in Figure 4. Potential pathways from the sources to the

receptors include ingestion of the sediments or water, direct contact with sediment or water,

bioconcentration from the water column, and bio-uptake of organisms. The receptors are humans,

piscivorous birds, pelagic fish, forage fish, bottom fish, benthos, and zooplankton.

Figure 10 shows the dredging scenario as implemented in ARAMS/FRAMES. Implementation of

the scenario begins with selection of the contaminants of concern and the receptor species. In the

generic scenario, the contaminant properties are selected from the FRAMES chemical database, and

ecological benchmark data for the chemical effects on receptors are selected from the ERED

database. Next, the source module, RECOVERY, is selected to describe the initial conditions in

the water column and temporal loadings from nonpoint sources, point sources, and inflow. The

source module is linked with the surface water modules. The RECOVERY and DREDGE models

were selected to model the contaminant interactions between the sediment, water column, and

atmosphere because of their flexibility and ease of use. Output from RECOVERY was linked to

ecological and human exposure models within FRAMES. Output from DREDGE was linked only

to ecological exposure modules because the transient exposure area is typically void of human

activities.