METHODOLOGY FOR THE SAMPLING OF METALS IN PRECIPITATION - RESULTS OF THE NATIONAL ATMOSPHERIC DEPOSITION PROGRAM (NADP) PILOT NETWORK

A pilot network of three U.S. sites was initiated to test the feasibil ity of quantitating arsenic, cadmium copper, manganese, lead, and zinc in wet deposition, and to make recommendations for a subnetwork at si te and training levels compatible with other wet deposition networks, specifically National Atmospheric Deposition Program (NADP). Modificat ions were made to Aerochem Metric samplers, including use of Teflon(R) surfaces, an insulated enclosure, and a thermostat controlled cooling fan and heater. Inductively coupled plasma mass spectrometry (ICP-MS) is well suited for the routine determination of the targeted metals a t the low mu g l(-1) concentrations. Relatively simple cleaning and ha ndling protocols are suitable for measuring metal concentrations at co ntinental levels in precipitation without introducing significant cont amination.