Sierra Nevada Aquatic Research Laboratory

06 Aug, 11 AM - 02 Sep, 03 AM

Critical loads for Rocky Mountain lakes have been recently estimated using historical relationships between diatom assemblages (as indicators of trophic status) and increases in atmospheric deposition of nitrogen (N). In the Sierra Nevada, we will use a similar approach to establish critical loads for N by developing a predictive model that is based upon modern water-quality measures and recently sedimented diatom assemblages in a large set of lakes. This model will be applied to diatoms in lake sediment cores collected along N deposition gradients in Yosemite (YOSE), and Sequoia and Kings Canyon National Parks (SEKI) in order to reconstruct limnetic N values over a period of approximately the last 100-200 years. We also will evaluate past changes in trophic state from the autecological preferences of sedimented diatom species and from diatom abundance, and by examining changes in depositional rates of nitrogen, phosphorus, and silica. By relating these indicators of ecological status to historic air pollution emissions, nearby deposition estimates and sediment-based reconstructions of atmospheric N deposition, we will deliver preliminary estimates of critical N loads for aquatic ecosystems in the Sierra Nevada. This project is a collaboration among researchers at the University of California Riverside (James Sickman), University of Florida (Mark Brenner), University of South Florida (Tom Whitmore), and with Air Resources Specialists for the National Park Service (Annie Esperanza and Leland Tarnay, SEKI and YOSE, respectively). The study is divided into three phases. Phase 1 involves collection and analysis of water and sediments samples from a large set of calibration lakes to be used in parameterizing and validating the trophic-state inference model. Phase 2 involves the collection and analysis of long sediment cores collected from three lakes showing evidence of changes from N deposition. These intensive lakes will be selected so that they fall along an N deposition gradient. The long cores will be up to 1 meter long and cover the last several hundred years of sediment deposition. Phase 3 involves application of the trophic state inference model to the long sediment cores, identification of trends in diatom species and N changes through time, and estimation of a critical load for N deposition in the Sierra Nevada.

Visit #12995 @Sierra Nevada Aquatic Research Laboratory

Approved

Under Project # 8530 | Research

Development of Critical Loads for Atmospheric Nitrogen Deposition to High Elevation Lakes in the Sierra Nevada

faculty - University of California, Riverside

Reservation Members(s)

Group of 2 Graduate Student Aug 6 - Sep 2, 2007 (28 days)
Group of 4 Research Assistant (non-student/faculty/postdoc) Aug 6 - Sep 2, 2007 (28 days)
James Sickman Aug 6 - Sep 2, 2007 (28 days)

Reserve Resources(s) | Create Invoice

Dorm 7 Aug 6 - Sep 2, 2007