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TRENDS IN SURFACE WATER ACIDIFICATION IN EUROPE AND NORTH AMERICA (1989-1998)
Citation:
Skjelkvale, B. L., J L. Stoddard, AND T. Andersen. TRENDS IN SURFACE WATER ACIDIFICATION IN EUROPE AND NORTH AMERICA (1989-1998). WATER, AIR, AND SOIL POLLUTION. Kluwer Academic Publishers, Hingham, MA, 130:787-792, (2001).
Description:
During the last 20 years, emission reductions in Europe and North America have resulted in decreased atmospheric Sulfur-deposition of up to 50%, while Nitrogen-deposition has stayed almost constant. Data from 98 ICP Waters sites were tested for trends in concentrations of major chemical components for the 10-year period 1989-1998 using the nonparametric seasonal Kendall test. The sites were grouped into regions and types for meta-analysis. All of the regions had highly significant downward trends in sulfate concentrations. Nitrate concentrations, on the other hand, show no regional patterns of change. Concentrations of base cations declined in most regions. All regions showed tendencies of increasing DOC. The low acid neutralizing capacity (ANC) sites showed the largest rates of recovery. Neither the high nitrate or low nitrate groups of sites exhibited significant trends in nitrate concentrations. Alpine (non-forested) sites show clear and consistent signals of recover in ANC and pH, and appropriate (relative to sulfate trends) rates of base cation decline.