Trends in atmospheric concentration and deposition compared to regional and local pollutant emissions at a rural site in southeastern New York, USA

Regional and national trends in eastern North America show declines in sulfur, nitrogen and base cation emissions and deposition from 1990 levels. We examined trends in the concentration of some gaseous and aerosol species as well as precipitation concentration of hydrogen ion, nitrogen, sulfur and base cation species at a site in southeastern New York. We compared trends in total sulfur and nitrogen deposition to local and regional emissions. Concentrations of gaseous SO2 and HNO3 and particles of SO42−, NH4+, Ca2+, Mg2+ and K+ in the <2 μm size range decreased during the 12-year period from 1988 to 1999. No change was observed during this period in aerosol concentrations of Na+, Cl− or NO3− in this small-particle size range. Concentrations of NH4+, NO3−, SO42− and H+ in precipitation declined from 1984 to 1999. Total sulfur and nitrogen deposition declined from 1988 to 1999. Changes in sulfur and nitrogen deposition correlated better with regional than local emissions. Air concentrations of SO2, NO3−, Na+ and Cl− were higher in winter than summer; all other air constituents were higher during summer than winter. In contrast to all other precipitation constituents, concentrations of Na+ and Cl− were higher in winter than in summer.