INADEQUACY OF NASQAN DATA FOR ASSESSING METAL TRENDS IN THE NATIONS RIVERS

Results of our analyses of dissolved Cd, Cu, Pb, and Zn in east coast North American rivers are considerably lower than those reported by the U.S. Geological Survey, National Stream Quality Accounting Network (NASQAN) for samples collected at similar locations during a similar time period. These results along with recent literature suggest that the NASQAN dissolved trace metal data are unreliable for the purpose of establishing water quality trends in the Nation's rivers. Dissolved trace metal concentrations in east coast rivers are probably controlled more by river chemistry than by anthropogenic inputs. Trace metal concentrations on suspended particles may provide a better index of anthropogenic influences.