Figure 7. Conceptual model for the no-action scenario

ERDC TN-DOER-R2

b. No-action conceptual model for

a. No-action pathway scenario

RECOVERY

Figure 8 shows the no-action 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 module. The RECOVERY model was selected to

model the contaminant interactions between the sediment, water column, and atmosphere, as shown

in Figure 7b, because of its flexibility and ease of use. Output from RECOVERY was linked to

ecological and human exposure models within FRAMES.

TBP is the ecological exposure model used to assess the effects of exposure to the contaminated

sediments and water on biota. The TBP model contains a BSAF database for selecting lipid fractions

for the receptor species and BSAF values for the contaminants of concern. TBP then estimates biota

body burden in equilibrium with contaminated sediments and water for all of the receptors and

contaminants of concern. The TBP model is linked with the ecological effects module to estimate

the risks associated with the body burdens.

WEAP is the ecological effects model used to estimate the risk as an ecological hazard quotient or

a probability of exceedance of ecological effects criteria. WEAP compares the biota body burden

against the effects levels from the ERED database. The model can also make simple comparisons

or can estimate statistical violations of criteria over given periods of time. It summarizes and

classifies the effects.

MEPAS is the human health exposure model used to calculate the exposure concentrations in media

(air, water, soil, and food) that will be exposed to humans (Buck et al. 1995). The concentrations

are passed to the MEPAS receptor intake module where the exposure doses are computed.

Additionally, the TBP model passes exposure concentrations of aquatic organisms for human