The National Atmospheric Deposition Program's National Trends Network and Mercury Deposition Network (NADP/NTN/MDN) is a nationwide network of 250 precipitation monitoring sites, of which 90 sites also collect samples for trace metals analysis. The network is a cooperative effort between many different groups, including the State Agricultural Experiment Stations, U.S. Geological Survey, U.S. Department of Agriculture, and numerous other governmental and private entities.

Over the past century acid rain and other conditions that are the result of ion fluctuations in rain water have been shown to deleteriously affect lives and ecosystems. Air contaminants originating from countless point sources and extended sources become entrained in air parcels and are advected away from the source to be later removed from the atmosphere by either dry or wet deposition processes. The NADP network is interested in the concentrations of ions that rain-out (wet deposition).

A precipitation collection field site (PA47) has been established about 1.8 km west of Millersville through long-term funding from the PA-DEP to continuously monitor liquid water equivalent (rain or melted snow). Students have been dutifully collecting samples every Tuesday since November 2002 in accordance with NADP collection and quality assurance protocols. Once the samples are collected, and after preliminary analysis at Millersville University, they are sent to national labs for detailed analysis of the following ions: Ca+2, Mg+2, K+, Na+, NH4+, NO3-, Cl-, SO4-2, and pH, and the trace metals, Hg.

This study will focus on the PA47 (Millersville) NADP/NTN and MDN databases and their context within the national database. Many factors affect the concentrations of ions and trace metals at a particular site, not the least of which is the meteorology and the amount of precipitation deposited from passing weather systems. Consequently, average monthly and annual concentrations can be very different from one period to the next. Overall, PA47 exhibits concentrations of ions and trace metals that are similar to sites in the eastern U.S. Since 1985, SO4 and NO3 show a slight decrease probably due to regulations that limit their emissions at the source. Ammonium as NH4+ shows no long term trend but varies between 2-4 kg/ha, while total inorganic nitrogen (N) varies between 4-7 kg/ha over the same period. The poster will expand upon the spatial and temporal trends for each ion and trace metal and show connections with the seasonal meteorology over the U.S.

Millersville University Department of Sciences has committed to a five year sample collection program (2002-2007), with the option for a five year renewal, which we are likely to do. Through the continuing efforts of site monitors, sponsors, and NADP/NTN/MDN, policy makers and regulators will have a robust database for informed decisions on the current state of atmospheric pollutants and the consequences of policy decisions.