Over the past 10-15 years atmospheric chemistry has evolved from a young research discipline devoted primarily to local problems of urban pollution and air quality to a mature science concerned with the hemispheric to global scale cycling of a wide variety of chemical species. To a large extent this change has resulted from an increasing realization that human activities can cause chemical disturbances to the natural troposphere on scales far beyond local concerns. Well-known examples include changes in the regional-to-global concentrations of certain nitrogen compounds, lead and other heavy metals, artificial radionuclides, a number of synthetic organic substances, certain acid-forming species, carbon dioxide and methane. These chemical changes in the atmosphere can often extend to the earth's soils, oceans, and biota far from the original source region. They can result in alterations in the earth's climate, changes in vital nutrient cycles, and impact significantly on the public health and quality of life on earth. The Atmosphere/Ocean Chemistry Experiment (AEROCE) will be a coordinated multi-institutional atmospheric and marine chemistry research project centered in the North Atlantic region. The ultimate goal of the AEROCE project will be the development of a predictive capability for the continentally derived species observed in the marine troposphere over the North Atlantic. The selection of sites and the measurement protocol in AEROCE has been developed jointly by modelers and field experimentalists. This element of the AEROCE project is concerned with examining trace elements (Al, As, Cd, Cu, Fe, Mn, Ni, Sb, Se, and Zn) in precipitation to the North Atlantic to assess atmospheric transport and deposition of continentally derived material to the sea. The North Atlantic is chosen because it is surrounded by relatively strong natural and anthropogenic sources of these elements. Precipitation is sampled because it is largely responsible for trace element deposition from the marine troposphere. The data will be compared to that in associated aerosols to help identify sources of trace elements over the North Atlantic, to help confirm associated air mass trajectory information, and to help evaluate the extent of trace element removal by marine precipitation. The corresponding wet flux data will reveal the contribution of precipitation to North Atlantic trace elements budgets. Specifically, these wet atmospheric fluxes comprise a significant portion of the global ocean flux and ultimately influence the biological productivity of oceanic surface waters. To meet the research objectives, the P.I.'s will utilize a carefully selected suite of trace elements, employ synoptic collection procedures, ensure accurate data through intercalibration and quality control protocols, and integrate fully with other research results.
