Paleolimnological assessment of high-elevation lakes exceeding critical loads of nitrogen deposition across the Greater Yellowstone Area
Expedition Date: August 2-23, 2018
Field Team Members: Jasmine Saros, Ben Burpee, Kate Warner, Leora Nanus & Julian Loguidici (San Francisco State University)
Expedition Funding Acknowledgement: US Forest Service Agreement 18-CS-11040300-051
Expedition Report: This project is building on recent work by the investigators that evaluated the spatial variation of atmospheric nitrogen (N) deposition and developed critical loads and exceedance maps across the Greater Yellowstone Area (GYA). A paleolimnological and lake chemistry assessment of high-elevation lakes is being used to determine whether they exceed the estimated critical load of N deposition and will provide information on diatom community changes in response to increasing atmospheric N deposition in recent years. Previous work on diatoms and lake chemistry is based on sampling that was conducted prior to 2010. Given the sharply increasing trends in atmospheric N deposition across the GYA since 2010, investigation to evaluate recent changes (2010-2018) is warranted.
High-elevation lakes that were sampled for diatoms and water chemistry prior to 2010 in the Beartooths were resampled; these lakes were selected based on predicted critical loads and exceedance maps to include lakes that span exceedance values. In addition, 2 lakes in Bridger-Teton and 2 lakes in Caribou-Targhee with long term records of water chemistry data were sampled. Surface sediment and water samples were collected from all lakes and analyzed for diatoms and water chemistry (major ions, total N & P, dissolved inorganic N & P).