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Mercury in Tadpoles Collected from Remote Alpine Sites in the Southern Sierra Nevada Mountains, California, USA
BRADFORD, D. F., J. L. Kramer, S. L. Gerstenberger, N. G. Tallent-Halsell, AND M. S. NASH. Mercury in Tadpoles Collected from Remote Alpine Sites in the Southern Sierra Nevada Mountains, California, USA. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY. Springer, New York, NY, 62:135-140, (2011).
The Sierra Nevada mountains of California (hereafter, Sierra Nevada) lie downwind from major regional sources of airborne pollutants from agriculture, industry, and transportation; the mountains may also receive pollutant inputs from trans-Pacific sources and the global atmospheric pool (Cahill et al. 1996; Landers et al. 2008). Atmospherically transported pollutants at high elevation (e.g., >2750 m) in the Sierra Nevada include both historic- and current-use pesticides, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), and metals (e.g., Cahill et al. 1996; Landers et al. 2008; Bradford et al. 2010b). Of particular concern, mercury (Hg) concentrations in brook trout (Salvelinus fontinalis) at high elevation have exceeded thresholds of risk to piscivorous wildlife (Schwindt et al. 2008). Moreover, damage to kidney and spleen in these fish was associated with elevated Hg concentrations, suggesting that Hg or another pollutant has affected fish health (Schwindt et al. 2008).
Amphibians in alpine wetlands of the Sierra Nevada mountains comprise key components of an aquatic-terrestrial food chain, and mercury contamination is a concern because concentrations in fish from this regin exceed thresholds of risk to piscivorous wildlife. Total mercury concentrations were measured in whole tadpoles of the Sierra chorus frog, Pseudacris sierra, two times at 27 sites from high elevations (2786 – 3375 m) in the southern Sierra Nevada. Median mercury concentrations were 14 ng/g wet mass (154 ng/g dry mass), which were generally low in comparison to tadpoles of 15 other species/location combinations from studies that represented both highly contaminated and little contaminated sites. Mercury concentrations in P. sierra were determined to be below toxic body burdens known for another amphibian species and below threshold concentrations for risk to predaceous wildlife. Concentrations in tadpoles were lower than those observed in fish in the study region presumably because tadpoles in the present study were much younger (1-2 mo) than fish in the other study (many years old), and tadpoles represent a lower trophic level than fish. Mercury concentrations were not related to distance from the adjacent San Joaquin Valley.
URLs/Downloads:BRADFORD 10-129 FINAL JOURNAL ARTICLE JOURNAL-FINAL MERCURY IN TADPOLES.PDF (PDF,NA pp, 63 KB, about PDF)
Mercury in Tadpoles Collected from Remote Alpine Sites in the Southern Sierra Nevada Mountains, California, USA Exit
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LABORATORY
ENVIRONMENTAL SCIENCES DIVISION
LANDSCAPE ECOLOGY BRANCH