Temporal, Directional, and Spatial Variability of Wet Deposition in the Northeastern United States

摘要

The precipitation chemistry data base of the Multistate Atmospheric Power Production Pollution Study and the National Atmospheric Deposition Program were examined for temporal, directional, and spatial variability of wet deposition of the dominant ions in precipitation for selected sites in the northeastern United States. Sulfate, hydrogen, and ammonium ions exhibited a distinct summer maxima in both concentration and deposition, while nitrate remained relatively constant throughout the years 1977-1979. Linear regression analysis applied to the three-year cumulative totals was found to provide a reasonable wet deposition predictive capability. The Air Resources Laboratories--Atmospheric Transport and Dispersion trajectory model was used to examine directional variability and to characterize individual events as to air mass origin. Case studies were examined to illustrate variability in the chemical quality of precipitation from air masses passing over distinctly different regions in the United States and Canada. The directional variability in wet deposition of all ions was found to coincide with the distribution of precipitation. The data of the MAP3S and NADP networks for 1979 were also used to develop spatial distributions of normalized and estimated wet deposition for the eastern United States. A rather uniform pattern in normalized wet deposition for sulfate and nitrate emerges, lending support to the concept that the deposition of these materials is not confined to any particular region. (Author)