Modelling the Detroit River aquatic and sediment systems

The International Joint Commission (IJC) has identified 43 Areas of Concern (AOC) on the Great Lakes. The Detroit River, a binational waterway, is one such AOC with impaired uses documented in the Stage I Remedial Action Plan (RAP) submitted to the IJC under the Great Lake Water Quality Agreement, including restrictions on fish and wildlife consumption due to Mercury contamination, degradation of benthic communities, and restrictions on dredging activities because of several metals including Mercury.; The objective of this study is to use the historical field data and to develop a comprehensive transport and fate model, including contaminant source/sink rates among three compartments (air, water, and sediment) and multiple point source contaminant discharges (municipal and industrial sources, tributaries, stormwater, and combined sewer overflows).; The Atmospheric and Sediment Deposition Model (ASDM) is a generalized temporal and spatial transport and fate model for predicting water, sediment, fish, suspended solid, plankton, porewater and benthos phase contaminant concentration profiles in the river. The model includes water column and surface sediment advection and dispersion, multimedia contaminant transport processes (air/water diffusion, water/sediment diffusion, dry and wet deposition, suspended solid settling, sediment resuspension and burial), intermedia contaminant partitioning processes (water/suspended solid sorption, porewater/sediment sorption, water/plankton sorption, porewater/benthos sorption, and fish sorption), and contaminant transformation processes (biolysis, hydrolysis, oxidation, and photolysis).; Comparisons of the model simulation results and measured data for the steady state Mercury concentrations in the Detroit River water column and surface sediment are in good agreement. All Mercury concentrations in the Detroit River water phase which exceed Michigan's Rule 57(2) Criteria (0.6 ng/l) are equivalently predicted by the simulation results, and most Mercury concentrations in the Detroit River sediment phase which are less than the Environmental Protection Agency's (EPA) Dredge Criteria (Heavily Polluted Value 1.0 mg/Kg) are comparable to the simulation results (Regression Line Slope: 0.7-1.3, Regression Line Intercept: 0.0, Regression Coefficient: 0.6-1.0).