Copper and zinc in estuarine waters near a coal fired electric power plant: correlation with oyster greening

Oysters in waters around the Chalk Point Power Plant, Maryland, accumulate copper, especially in the summer; however it appears that the power plant itself is not the primary copper source. A series of water samples collected in the summer of 1972 and analysed for both Cu and Zn reveal first that the concentration of both metals increased during the summer, second that this increase was greatest in bottom waters, and third that waters near the power plant contained more copper than thos elsewhere. Horizontal distribution of copper in the water agrees with the previously observed horizontal distribution of copper accumulation in oysters. The maximum Cu concentration observed in the water was 31. 5 ug/1; maximum Zn was 50. 4 ug/1. It is suggested that the power plant's cooling water, which contains dissolved oxygen and is chlorinated during the summer, is oxidizing metal-rich organic matter and sulfides in the sediments near the plant, releasing Cu and Zn to the water.