Web Release Date: April 15,
Atmospheric Deposition of Current-Use and Historic-Use Pesticides in Snow at National Parks in the Western United States
and
Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon 97331, Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States Geological Survey, Denver, Colorado 80225, and United States Environmental Protection Agency-Western Ecology Division, Corvallis, Oregon 97330
Received for review January 23, 2006
Revised manuscript received March 15, 2006
Accepted March 21, 2006
Abstract:
The United States (U.S.) National Park Service has
initiated research on the atmospheric deposition and fate
of semi-volatile organic compounds in its alpine, sub-Arctic, and Arctic ecosystems in the Western U.S. Results
for the analysis of pesticides in seasonal snowpack
samples collected in spring 2003 from seven national
parks are presented herein. From a target analyte list of
47 pesticides and degradation products, the most frequently
detected current-use pesticides were dacthal, chlorpyrifos,
endosulfan, and 
-hexachlorocyclohexane, whereas the
most frequently detected historic-use pesticides were dieldrin,
-hexachlorocyclohexane, chlordane, and hexachlorobenzene. Correlation analysis with latitude, temperature, elevation,
particulate matter, and two indicators of regional pesticide
use reveal that regional current and historic agricultural
practices are largely responsible for the distribution of
pesticides in the national parks in this study. Pesticide
deposition in the Alaskan parks is attributed to long-range
transport because there are no significant regional
pesticide sources. The percentage of total pesticide
concentration due to regional transport (%RT) was calculated
for the other parks. %RT was highest at parks with
higher regional cropland intensity and for pesticides with
lower vapor pressures and shorter half-lives in air.
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