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Impacts of changing climate and atmospheric deposition on N and S drainage losses from a forested watershed of the Adirondack Mountains, New York State
Author(s) -
Park JiHyung,
Mitchell Myron J.,
McHale Patrick J.,
Christopher Sheila F.,
Meyers Tilden P.
Publication year - 2003
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1046/j.1365-2486.2003.00686.x
Subject(s) - deposition (geology) , biogeochemical cycle , watershed , precipitation , environmental science , hydrology (agriculture) , nitrogen , flux (metallurgy) , environmental chemistry , particulates , atmospheric sciences , chemistry , sediment , geology , meteorology , geography , geomorphology , geotechnical engineering , organic chemistry , machine learning , computer science
Biogeochemical responses to changing climate and atmospheric deposition were investigated using nitrogen (N) and sulfur (S) mass balances, including dry deposition and organic solutes in the Arbutus Lake watershed in the Adirondack Mountains, New York State. Long‐term monitoring of wet‐only precipitation (NADP/NTN, 1983–2001) and dry deposition (AIRMoN, 1990–2001) at sites adjacent to the watershed showed that concentrations of SO 4 2− in precipitation, SO 4 2− in particles,and SO 2 vapor all declined substantially ( P <0.005) in contrast to no marked temporal changes observed for most N constituents (NH 4 + in precipitation, HNO 3 vapor, and particulate NO 3 − ), except for NO 3 − in precipitation, which showed a small decrease in the late 1990s. From 1983 to 2001, concentrations of SO 4 2− in the lake outlet significantly decreased (−2.1 μeq L −1 yr −1 , P <0.0001), whereas NO 3 − and dissolved organic N (DON) concentrations showed no consistent temporal trends. With the inclusion of dry deposition and DON fluxes into the mass balance, the retained portion of atmospheric N inputs within the main subcatchment increased from 37% to 60%. Sulfur outputs greatly exceeded inputs even with the inclusion of dry S deposition, while organic S flux represented another source of S output, implying substantial internal S sources. A significant relationship between the annual mean concentrations of SO 4 2− in lake discharge and wet deposition over the last two decades ( r =0.64, P <0.01) suggested a considerable influence of declining S deposition on surface water SO 4 2− concentrations, despite substantial internal S sources. By contrast, interannual variations in both NO 3 − concentrations and fluxes in lake discharge were significantly related to year‐to‐year changes in air temperature and runoff. Snowmelt responses to winter temperature fluctuations were crucial in explaining large portions of interannual variations in watershed NO 3 − export during the months preceding spring snowmelt (especially, January–March). Distinctive response patterns of monthly mean concentrations of NO 3 − and DON in the major lake inlet to seasonal changes in air temperature also suggested climatic regulation of seasonal patterns in watershed release of both N forms. The sensitive response of N drainage losses to climatic variability might explain the synchronous patterns of decadal variations in watershed NO 3 − export across the northeastern USA.