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 feasibility of quantitating arsenic, cadmium, copper, manganese, lead, and zinc in wet deposition, and to make recommendations for a subnetwork at site and training levels compatible with other wet deposition networks, specifically National Atmospheric Deposition Program (NADP). Modifications were made to Aerochem Metric samplers, including use of Teflon® 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 at the low μg ℓ−1 concentrations. Relatively simple cleaning and handling protocols are suitable for measuring metal concentrations at continental levels in precipitation without introducing significant contamination.