Assessment of Impact of Organic Pollutants on Fish in the Minnesota River Watershed by Hepatic Aminopyrine N-Demthylase Activity

Fish samples were taken from two mainstem and two tributary sites in the Minnesota River Basin. These samples were tested for liver microsomal aminopyrine N-demethylase activity and PCBs. The PCB levels were compared with both fish weight and aminopyrine N-demethylase activity. The results varied with each site and year. They were able to conclude that PCB contamination does not vary considerably by year. However, aminopyrine N-demethylase activity does indicate that impacts are greater in the mainstem Minnesota River during a low water year. Tributaries are most impacted during periods of high runoff.