Changes in the chemistry of lakes and precipitation in high-elevation national parks in the western United States, 1985

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Read Full Article (file size: 2617811 bytes) Cited by WATER RESOURCES RESEARCH, VOL. 39, NO. 6, 1171, doi:10.1029/2002WR001533, 2003 Changes in the chemistry of lakes and precipitation in high-elevation national parks in the western United States, 1985–1999 David W. Clow Water Resources Division, U.S. Geological Survey, Denver, Colorado, USA James O. Sickman Environmental Services Division, California Department of Water Resources, Sacramento, California, USA Robert G. Striegl Water Resources Division, U.S. Geological Survey, Denver, Colorado, USA David P. Krabbenhoft Water Resources Division, U.S. Geological Survey, Middleton, Wisconsin, USA John G. Elliott Water Resources Division, U.S. Geological Survey, Denver, Colorado, USA Mark Dornblaser Water Resources Division, U.S. Geological Survey, Denver, Colorado, USA David A. Roth Water Resources Division, U.S. Geological Survey, Denver, Colorado, USA Donald H. Campbell Water Resources Division, U.S. Geological Survey, Denver, Colorado, USA Abstract High-elevation lakes in the western United States are sensitive to atmospheric deposition of sulfur and nitrogen due to fast hydrologic flushing rates, short growing seasons, an abundance of exposed bedrock, and a lack of well-developed soils. This sensitivity is reflected in the dilute chemistry of the lakes, which was documented in the U.S. Environmental Protection Agency's Western Lake Survey of 1985. Sixty-nine lakes in seven national parks sampled during the 1985 survey were resampled during fall 1999 to investigate possible decadal-scale changes in lake chemistry. In most lakes, SO₄ concentrations were slightly lower in 1999 than in 1985, consistent with a regional decrease in precipitation SO₄ concentrations and in SO₂ emissions in the western United States. Nitrate concentrations also tended to be slightly lower in 1999 than in 1985, in contrast with generally stable or increasing inorganic N deposition in the west. Differences in alkalinity were variable among parks but were relatively consistent within each park. Possible effects of annual and seasonal-scale variations in precipitation amount on lake chemistry were evaluated based on climate data available for the parks and an analysis of climatic effects at two research watersheds with long-term records. Results suggest that rain prior to sampling in 1985 may have caused elevated NO₃ in some lakes due to direct runoff of precipitation and flushing of NO₃ from alpine soils, which may explain some of the decrease in NO₃ concentrations observed in survey lakes. Received 19 June 2002; accepted 18 March 2003; published 26 June 2003. Index Terms: 1803 Hydrology: Anthropogenic effects; 1806 Hydrology: Chemistry of fresh water; 1845 Hydrology: Limnology; 1854 Hydrology: Precipitation (3354); 1871 Hydrology: Surface water quality. Read Full Article (file size: 2617811 bytes) Cited by Citation: Clow, D. W., J. O. Sickman, R. G. Striegl, D. P. Krabbenhoft, J. G. Elliott, M. Dornblaser, D. A. Roth, and D. H. Campbell (2003), Changes in the chemistry of lakes and precipitation in high-elevation national parks in the western United States, 1985–1999, Water Resour. Res., 39(6), 1171, doi:10.1029/2002WR001533. This paper is not subject to U.S. copyright. Published in 2003 by the American Geophysical Union.

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