Arland H. Johannes

The integrated lake-watershed acidification study: Atmospheric inputs

Atmospheric inputs to Woods, Panther, and Sagamore Lake-Watersheds in the Adirondack Mountains of New York State were measured on a daily basis from March 1978 through December 1981. Precipitation quality was nearly identical at all sites on monthly and yearly bases; ion loadings to each watershed were principally controlled by the amount of precipitation. No yearly trend was evident for any ion concentration in wet deposition. Annual precipitation quantities showed little deviation from long-term averages for this region. Throughfall measured under various species of trees showed enrichment in most base cations and acid anions. Deciduous trees were found to increase the pH of incident precipitation, while coniferous canopies tended to decrease pH.

Spatial and historical trends in acidic deposition: A graphical intersite comparison☆

Abstract Precipitation chemistry from different regions of the Continental United States is characterized in terms of a graph of annual mean μ (+) vs μ(−), where μ (+) = Ca2+ +Mg+2 + NH+4 + K+ and Na+,and σ (−) = SO2−4 + NO −3 + Cl−; concentrations are given in μeq. l−1. Sites receiving acid precipitation (pH 4.5) tend to cluster near a line of slope one. Four regions. North Central (Minnesota, Wisconsin), Midwest (Illinois, Ohio), East Central (North Carolina, Virginia), and North East (Pennsylvania, New York, Vermont, New Hampshire, Maine) are presented as areas in terms of minimum and maximum μ (+) and μ (−) values. Seasonal variations of μ (+) and σ (−) tend to occur along lines of constant slope within these regions. The results from the last decade have been compared with the few measurements from the 1950s. Although one possible interpretation from this comparison is that σ(−) has increased in one or more of the regions considered, this view is tempered by the inherent difficulty in comparing single sites with regions.