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Temporal and Spatial Variation of Atmospherically Deposited Organic Contaminants at High Elevation in Yosemite National Park, California, USA
Citation:
Bradford, D., K. Stanley, N. Tallent, D. Sparling, M. Nash, R. Knapp, L. McConnell, AND S. Simonich. Temporal and Spatial Variation of Atmospherically Deposited Organic Contaminants at High Elevation in Yosemite National Park, California, USA. E. Zeng (ed.), ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 32(0):517-525, (2013).
Impact/Purpose:
Article elucidates contaminant distribution in two media in time and space in remote mountains of California, including relevance to guideline thresholds. Details in Abstract.
Description:
Atmospherically deposited organic contaminants in the Sierra Nevada mountains of California, USA, have exceeded some thresholds of concern, but the spatial and temporal distributions of contaminants in the mountains are not well known. The present study evaluated (1) whether the concentrations of pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) at high elevations within Yosemite National Park in the central Sierra Nevada differ from concentrations observed previously in Sequoia-Kings Canyon National Parks in the southern Sierra Nevada, and (2) the variation in contaminant concentrations in Yosemite among sites, among years, and within years. We sampled shallow-water sediment and tadpoles (Pseudacris sierra) in four high-elevation sites in Yosemite twice during the summers of 2006, 2007, and 2008. Both historic- and current-use pesticides showed a striking pattern of greater concentrations in both media in Sequoia-Kings Canyon than in Yosemite. By contrast, PAH concentrations in sediment were generally greater in Yosemite than in Sequoia-Kings Canyon. We suggest that pesticide concentrations tend to be greater in Sequoia-Kings Canyon because of a longer air flow path over agricultural lands for this park, and that PAHs tend to be greater in Yosemite due to greater vehicular traffic in Yosemite. A general pattern of difference between Yosemite and Sequoia-Kings Canyon was not evident for total tadpole cholinesterase activity, an indicator of exposure to organophosphorus and carbamate pesticides. Variability of chemical concentrations among sites, between sampling periods within each year, and among years contributed significantly to total variation, although the relative contributions differed between sediment and tadpoles.