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REGIONAL APPLICATION OF A BIOGEOCHEMICAL MODEL (PNET-BGC) TO THE ADIRONDACK REGION OF NEW YORK: RESPONES TO CURRENT AND FUTURE CHANGES IN ATMOSPHERIC DEPOSITION
Citation:
Impact/Purpose:
To increase our understanding of the response of Adirondacks to changes in acid deposition
Description:
Understanding the response of soil and surface waters to changes in atmospheric deposition is critical for guiding future legislation on air pollutants. In this study, the regional response of soil and surface waters in 37 lake watersheds in the Adirondack region of New York to changes in atmospheric deposition and future control scenarios were evaluated, through the application of a biogeochemical model (PnET-BGC). Results indicated that the model generally captured chemical trends observed in lakes of the region between 1984 and 2001. Model forecast simulations indicated that under future control scenarios, surface water SO4^2- and NO3^- generally decrease. Lake acid neutralizing capacity ANC and soil percent base saturation (%BS) increase. However under the 1990 Amendments of the Clean Air Act, 20% of the lakes remain acidic (ANC < 0 meq/L). Additional emission controls will result in more rapid decreases in SO4^2- and NO3^- and more significant recovery in surface water ANC and soil %BS. Under the aggressive control scenario, surface water SO4^2- concentrations ranged between 20 to 40 meq/L and percent of acidic lakes declined to only 10%. Although marked improvement might be expected, full chemical and associated biological recovery will likely not be achieved for all the sites in 2050. Around 40% of the sites still have Ca/Al ratio in soil solution less than 1.0 and more than 50% of the sites have soil %BS less than 20%.