HR: 0800h
AN: GC41A-0109    [Abstracts]
TI: An Investigation of the Impacts of Climate and Environmental Change on Alpine Lakes in the Uinta Mountains, Utah
AU: * Moser, K A
EM: kmoser@uwo.ca
AF: Dept. of Geography, University of Western Ontario, Social Science Center 1151 Richmond St. North, London, ON N5Y 2S9, Canada
AU: Hundey, E J
EM: ehundey@uwo.ca
AF: Dept. of Geography, University of Western Ontario, Social Science Center 1151 Richmond St. North, London, ON N5Y 2S9, Canada
AU: Porinchu, D F
EM: porinchu@osu.edu
AF: Dept. of Geography, The Ohio State University, 1036 Derby Hall 154 North Oval Mall, Columbus, OH 43210-1361, United States
AB: Aquatic systems in alpine and sub-alpine areas of the western United States are potentially impacted by atmospheric pollution and climate change. Because these mountainous regions are an important water resource for the western United States, it is critical to monitor and protect these systems. The Uinta Mountains are an east- west trending mountain range located on the border between Utah, Wyoming and Colorado and downwind of the Wasatch Front, Utah, which is characterized by a rapidly expanding population, as well as mining and industry. This alpine area provides water to many areas in Utah, and contributes approximately nine percent of the water supply to the Upper Colorado River. Our research is focused on determining the impacts of climate change and pollution on alpine lakes in the Uinta Mountains. The results presented here are based on limnological measurements made at 64 Uinta Mountain lakes spanning a longitude gradient of one degree and an elevation gradient of 3000 feet. At each lake maximum depth, conductivity, salinity, pH, Secchi depth, temperature, alkalinity, and concentrations of major anions, cations and trace metals were measured. Principal Components Analysis (PCA) was performed to determine relationships between these variables and to examine the variability of the values of these variables. Our results indicate that steep climate gradients related to elevation and longitude result in clear differences in limnological properties of the study sites, with high elevation lakes characterized by greater amounts of nitrate and nitrite compared to low elevation sites. As well, diatoms in these lakes indicate that many high elevation sites are mesotrophic to eutrophic, which is unexpected for such remote aquatic ecosystems. We hypothesize that elevated nitrate and nitrite levels at high elevation sites are related to atmospherically derived nitrogen, but are being exacerbated relative to lower elevation sites by greater snow cover and reduced plant cover. Paleolimnological analyses of well dated sediments from selected lakes indicate that some of these high elevation sites have undergone rapid and dramatic change beginning in the late 1800s to early 1900s. Many of these lakes have become more productive as indicated by loss-on-ignition and diatom analyses. Although the exact mechanism of these changes is uncertain, the timing closely follows recent increases in air and chironomid-inferred surface water temperatures, and increased fossil fuel burning in the region. Regardless of the exact mechanism, our results clearly indicate dramatic changes at these high elevation sites, which threaten critical water resources.
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1630 Impacts of global change (1225)
DE: 1836 Hydrological cycles and budgets (1218, 1655)
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting