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ESTIMATION OF CRITICAL LOADS OF ACIDITY FOR LAKESIN NORTHEASTERN UNITED STATES AND EASTERN CANADA
Citation:
DUPONT, J., T. A. CLAIR, C. GAGNON, D. S. JEFFRIES, J. KAHL, S. J. NELSON, AND J. M. PECKENHAM. ESTIMATION OF CRITICAL LOADS OF ACIDITY FOR LAKESIN NORTHEASTERN UNITED STATES AND EASTERN CANADA. ENVIRONMENTAL MONITORING AND ASSESSMENT. Springer, New York, NY, , 1-18, (2004).
Description:
The New England Governors and Eastern Canadian Premiers (NEG/ECP) adopted the Acid Rain Action Plan in June 1998, and issued a series of action items to support its work toward a reduction of sulfur dioxide (SO2) and nitrogen oxide (NOx ) emissions in northeastern North America. One of these action items was the preparation of an updated critical load map using data from lakes in the NEG/ECP area. Critical load maps provide a more complete index of the surfacewater sensitivity to acidification. Combined sulfur and nitrogen critical loads and deposition exceedances were computed using Henriksen’s Steady-State Water Chemistry (SSWC) model. Results show that 28% of all 2053 lakes studied have a critical load of 20 kg/ha/year or less, making them vulnerable to acid deposition. Emission reductions, and more specifically SO2 emission reductions have proven beneficial because critical loads were exceeded in 2002 for 12.3% of all studied lakes. Those lakes are located in the more sensitive areas where geology is carbonate-poor. Of these lakes, 2.9% will never recover even with a complete removal of SO4 deposition. Recovery from acidification for the remaining 9.4% of the lakes will require additional emission SO2 reductions.