Environmental Health - Toxic Substances Hydrology Program
Vernal pools are temporary or ephemeral wetlands. They contain water during cooler, wetter seasons, but dry up during warmer, dryer times of the year. Some vernal pools fill only with runoff from precipitation, whereas others are filled from shallow groundwater inputs (Zedler 2003).
In a recent paper published in Environmental Monitoring and Assessment, scientists from the U.S. Geological Survey (USGS), National Park Service (NPS), and U.S. Fish and Wildlife Service (FWS) reported that measurable concentrations of glyphosate, atrazine, and 25 other pesticides; pesticide transformation products; and caffeine were detected in vernal pools in four parks and refuges across the country. Vernal pools contain water for part of the year then eventually dry up. They usually don't contain fish, but are key habitat for some organisms, including amphibians. The vernal pools studied are located in a National Wildlife Refuge in Iowa, a National Park in Washington, D.C., a National Historical Park in Maryland, and a State Park in Wyoming. The scientists detected some pesticides in all vernal pools sampled. Pesticides were detected more frequently and at higher concentrations in vernal pools that were adjacent to land were pesticides were being used to control invasive plants or to control weeds in agricultural areas than at sites more distant from pesticide-use areas. The results indicate that vernal pools can be susceptible to contamination from pesticides applied both in and nearby park and refuge lands, and that assessing the potential effects of pesticides on vernal pool ecosystems, including amphibians, is warranted. Land and water-resource managers can potentially use these results to help determine how best to control invasive plants and other pests in parks and refuges.
This project was supported in part by the USGS's Amphibian Research and Monitoring Initiative (ARMI), which is a multi-agency, Department of the Interior (DOI) initiative to (1) conduct long-term monitoring to determine trends in amphibian populations, (2) investigate the causes of amphibian declines and malformations, and (3) disseminate available information on amphibians to land managers and the public.
Battaglin, W.A., Rice, K.C., Focazio, M.J., Salmons, S., and Barry, R.X., 2008, The occurrence of glyphosate, atrazine, and other pesticides in vernal pools and adjacent streams in Washington, DC, Maryland, Iowa, and Wyoming, 2005-2006: Environmental Monitoring and Assessment, doi:10.1007/s10661-008-0435-y (Advanced Web release).
Zedler, P.H., 2003, Vernal pools and the concept of "isolated wetlands": Wetlands, v. 23, no. 3, p. 597-607, doi:10.1672/0277-5212(2003)023[0597:VPATCO]2.0.CO;2.