Investigation of Mercury Deposition and Sources of Mercury Input to Four Western National Parks and One California State Park

Genine Wright1, Mae Gustin1 and Peter Weiss-Penzias2

A recent project, the Western Airborne Contaminants Assessment Project (WACAP) showed that fish in eight parks of the western U.S. had mercury concentrations that exceeded the threshold for fish eating wildlife ( These observations led to the development of this study focused on investigating air mercury concentrations and potential for dry deposition using newly developed passive samplers and surrogate surfaces. Samples will be collected simultaneously along a transect from the coast of California to the eastern edge of Nevada. Sampling locations are located within the Point Reyes, Yosemite, Sequoia and Great Basin National Park units and at Lick Observatory on Mt. Hamilton, CA. Dry deposition using surrogate surfaces and air Hg speciation are also being measured at Elkhorn Slough.

Investigation of elevational gradients in air concentrations and deposition within select parks during sampling intensives will allow us to better understand the sources of Hg to park ecosystems. Recent work suggests that RGM may be formed in the free troposphere from elemental Hg in the global pool. This Hg would be more available at higher elevation sites.

To better understand changes in atmospheric deposition and air concentrations over time and the potential relationship to current and future climate, Hg concentrations in tree rings will be measured. We will also link our work with sediment core data collected in the past and to better understand potential ecosystem inputs and potential for changing deposition. Modeling with HYSPLIT back trajectories will be done to investigate air masses impacting areas during the weeks of sampling.

1Department of Natural Resources and Environmental Science University of Nevada-Reno
2Department of Environmental Toxicology University of California at Santa Cruz
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