Wet deposition of current‐use pesticides in the Sierra Nevada mountain range, California, USA

Abstract

Abstract-Atmospheric inputs of pesticides transported from California's Central Valley to the Sierra Nevada mountains (California, USA) were investigated by collecting winter-spring precipitation (rain and snow) from Sequoia National Park and from the Lake Tahoe basin. Pesticides currently used in California's Central Valley were detected in snow and rain samples from two elevations in Sequoia National Park (SNP) in the southern Sierras. At the lower elevation site (533 m), chlorothalonil was present at the highest levels (Ͻ0.4-85 ng/L), followed by malathion (Ͻ0.046-24 ng/L), diazinon (Ͻ0.21-19 ng/L), and chlorpyrifos (1.3-4.4 ng/ L). At 1,920 m elevation, chlorothalonil was also present at the highest levels (Ͻ0.57-13 ng/L) followed by diazinon (Ͻ0.057-14 ng/L), chlorpyrifos (1.1-13 ng/L), and malathion (Ͻ0.045-6 ng/L). Trifluralin, ␣-and ␥-hexachlorocyclohexane (HCH), and ␣-and ␤-endosulfan were also detected at both locations and at lower concentrations, generally ranging from 0.5 to 2 ng/L. In the Lake Tahoe basin, elevation 2,200 m, malathion was also found in snow at concentrations ranging from Ͻ0.046 to 18 ng/L, as was diazinon (Ͻ0.057-7 ng/L), chlorpyrifos (0.30-3.4 ng/L), and chlorothalonil (0.66-1.7 ng/L). Chlorothalonil, chlorpryifos, ␣-and ␥-HCH, and ␣-endosulfan were found in surface and deep water samples at two locations in Lake Tahoe and at concentrations similar to those found in snow within the lake basin. Lake Tahoe basin snow samples in general had lower concentrations than those from SNP. This difference in concentration levels reflects the closer proximity of downwind pesticide usage to SNP than the Lake Tahoe basin. An estimated annual loading of one chemical, chlorpyrifos, of 24 to 31 kg/year was made for the SNP land area. Comparisons of observed concentrations were made with reported aquatic toxicity and water criteria levels.

Deposition and accumulation of airborne organic contaminants in Yosemite National Park, California

“…For example, mean concentrations of chlorpyrifos in Yosemite (1.8 ng/L) and Sequoia (2.3 ng/L) were more than an order of magnitude higher than in national parks in Colorado (0.03 ng/L) and Montana (0.07 ng/L) [23,24], which likely reflects higher application rates in the San Joaquin Valley. In an earlier study in Sequoia, chlorpyrifos and endosulfans were also detected in snow as well as chlorothalonil, diazinon, and malathion [19], which were not included in the present study.…”

“…The herbicide atrazine was frequently detected in rain at a high-elevation site in the Rocky Mountains [24]. Atrazine was not detected in any samples from Yosemite or Sequoia [2,19], which likely reflects low application rates in the San Joaquin Valley (<50 kg annually).…”

“…Several studies have reported pesticide concentrations in fish and amphibians [6,11,[14][15][16][17][18], although measurements of pesticides in the atmosphere and aquatic habitats are relatively sparse. Pesticide concentrations in wet deposition [19] and in air, dry deposition, and surface water [2] were measured in Sequoia and Kings Canyon National Parks (Fig. 1), located in the Sierra Nevada near the southern end of the San Joaquin Valley.…”

Current-Use and Legacy Pesticide History in the Austfonna Ice Cap, Svalbard, Norway

“…Other investigations have observed OC pesticides in snow and ice from mountainous and arctic areas of North America and Russia (11)(12)(13). Previous research on OPs shows that they are distributed through the atmosphere to sites at considerable distances from areas of use (14)(15)(16)(17), and are found in arctic sea ice, land ice, and lake water (4,12,14).…”

Temporal and spatial variation of atmospherically deposited organic contaminants at high elevation in yosemite national park, California, USA

“…Ranges that lie in close proximity and downwind from areas of high population density, intense agriculture, or intense industrial activity, such as the European Alps, the southern slope of the Himalayas, the Sierra Nevada of California, USA, and the mountains of Costa Rica may be particularly vulnerable [2,3]. The present study focuses on the Sierra Nevada mountain range, which lies adjacent to one of the highest agricultural pesticide-use areas in North America, the Central Valley of California [4]. Even in the remote alpine zone at high elevation (i.e., near or above timberline, >2,750 m), the occurrence of pesticides and other airborne contaminants is well documented [5][6][7][8][9][10], and concern has arisen that airborne contaminants may be having adverse effects on biota at high elevation.…”