ORSANCO conducted two special studies of mercury. The first study, on the mainstem of the Ohio River, evaluated concentrations of mercury in the Ohio River and its bioaccumulation in fish. Mercury water samples were collected monthly at three Ohio River locations for one year and compared to mercury levels in fish tissue. Results of the study provided information on changes in mercury concentrations seasonally and with flow, ratios of total mercury to methyl mercury in fish, and methylmercury bioaccumulation rates in fish tissue resulting from water concentrations in the Ohio River. The second study was a survey of mercury in major tributaries to the Ohio River. Monthly mercury samples were collected from the fourteen largest tributaries to the Ohio River for one year. Results of the study provided information on the amount of mercury in the Ohio River being input from its major tributaries, as well as information on changes in seasonal and flow variability in mercury from these tributaries. For more information, please contact Sam Dinkins.