Organic carbon and chemical contaminant relationships in river and lake sediments

Sediment collected from 11 sites within the Fox and East Rivers of Brown County, Wisconsin, and two near-shore sites in Green Bay (Lake Michigan) were analyzed for organic carbon content and various pesticides, polychlorinated biphenyls (PCBs), chlorodibenzodioxins, chlorodibenzofurans, polycyclic aromatic hydrocarbons (PAHs), sulfur and heavy metals. Representative chemicals from the organic and inorganic groups were examined for their concentrations at the various sites relative to organic carbon content. Correlations between organic carbon and contaminant concentrations resulted in simple linear regression models with high degrees of predictive capability for most chemicals. For example, chemical concentration relationships with organic carbon (r{sup 2}) were p,p{prime}-DDE (0.85), total PCBs (0.69), 2,3,7,8-tetrachlorodibenzodioxin (0.76), 1,2,3,6,7,8-hexachlorodibenzodioxin (0.87), 2,3,7,8-tetrachlorodibenzofuran (0.71), fluoranthene (0.46), pyrene (0.51), total sulfur (0.75), cadmium (0.76), copper (0.84), lead (0.85), zinc (0.80), chromium (0.04), and nickel (0.39). All correlations were positive with the exception of nickel. This suggests that contaminants within the lower Fox River/Green Bay system are at steady-state with respect to organic carbon. Knowledge of relationships such as this within aquatic systems may be useful in planning and budgeting contaminant mass balance studies within the systems.