Technical Integrity / Collaboration / Exceptional Results

South River

The South River is a riverine system impacted by elevated concentrations of mercury and methylmercury. Integral scientists used OPTICS to evaluate processes influencing water column concentrations over a 6-week pilot study in spring 2016. The results of the monitoring showed 1) a steady increase in dissolved methylmercury as water temperatures rose, consistent with increased microbiological activity; 2) an increase in particulate mercury and methylmercury concentrations resulting from sediment resuspension from the river bottom and banks during a storm event; and 3) a 24-hour pattern in particulate concentrations under baseflow conditions, with concentrations increasing at nighttime consistent with nocturnal bioturbation. These findings of the OPTICS study validate key elements of the conceptual site model that are critical considerations of the adaptive remedy being implemented at the site.

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