Mercury Distribution and Cycling in Sierra Nevada Waterbodies

EPA Grant Number: R825433C030
Subproject: this is subproject number 030 , established and managed by the Center Director under grant R825433
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EERC - Center for Ecological Health Research (Cal Davis)
Center Director: Rolston, Dennis E.
Title: Mercury Distribution and Cycling in Sierra Nevada Waterbodies
Investigators: Heyvaert , Alan C. , Reuter, John E. , Goldman, Charles R. , Slotton, Darell
Institution: University of California - Davis
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1996 through September 30, 2000
RFA: Exploratory Environmental Research Centers (1992) RFA Text |  Recipients Lists
Research Category: Center for Ecological Health Research , Targeted Research


This project seeks to study the biogeochemistry of mercury in Sierra Nevada waterbodies, specifically, the current and historical atmospheric deposition of mercury and lead at Lake Tahoe. Those that exist have focused on the urban-industrial centers of Seattle and Los Angeles.


To date there have been few studies of atmospheric deposition of trace metals on the continental west coast. Those that exist have focused on the urban-industrial centers of Seattle and Los Angeles. Baseline rates and historical deposition patterns have only been reconstructed from sites off the coast of southern California and from remote sites in Alaska.

This study looked at the history of atmospheric Hg deposition in the Sierra Nevada mountains of California and Nevada, over a relatively pristine watershed where there has never been any recorded use of Hg. The investigators compared the modern rates of Hg deposition in this area to historical baseline rates in order to discern any signal associated with Hg consumption during the late 1800s at mining districts adjacent to the Tahoe basin. In this paleolimnological reconstruction they also examined Pb accumulation rate as a useful comparative metric to Hg deposition, and compare the results for both Pb and Hg to sediment concentrations and flux estimates from similar studies in other regions of North America.

Concentrations of Pb and Hg in the sediments of Lake Tahoe deposited prior to 1850 are similar to bedrock concentrations in the watershed. Over these baseline values, however, surface sediment concentrations have increased six-fold for Pb (average 83 ppm) and five-fold for Hg (average 0.191 ppm). Lake Tahoe occupies a relatively pristine, moderately urbanized, non-industrial, subalpine basin .With a watershed to lake surface ratio of only 1.6, any excess accumulation of trace metal in the sediments of Lake Tahoe should closely reflect direct atmospheric deposition. On average, since 1980 there have been approximately 14 mg Pb and 36 µg Hg deposited annually per square meter in excess of baseline flux. While local emissions for Pb existed in the combustion of leaded gasoline until about 1985, the atmospheric deposition of Hg must represent a predominately regional to global source of contamination. Ratios of total modern flux to preindustrial flux are 25 for Pb and 21 for Hg. This flux ratio for Pb is somewhat higher than reported from the eastern USA and Canada, but is not atypical. The Hg flux ratio, however, is much higher than observed in most other natural aquatic systems without point-source contamination.

Expected Results:

Evidence from this study is expected to suggest the existence of a significant source for atmospheric Hg deposition in the high Sierras on the continental west coast of the USA.

Supplemental Keywords:

Watershed, aquatic ecosystem, Sierra Nevada, mercury, atmospheric deposition, ecosystem assessment, mercury, lead, trace metals., RFA, Scientific Discipline, INTERNATIONAL COOPERATION, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Water & Watershed, Restoration, Aquatic Ecosystem, Environmental Microbiology, Biochemistry, Terrestrial Ecosystems, Ecology and Ecosystems, Aquatic Ecosystem Restoration, Watersheds, contaminant exposure, biogeochemical study, biodiversity, watershed management, mercury, lead, nutrients, restoration strategies, hydrology, wetland restoration, integrated watershed model, aquatic ecosystems, environmental stress, watershed sustainablility, Sierra Nevada, ecosystem stress, ecology assessment models, ecological impact, aquatic habitat protection , land use, ecological research

Progress and Final Reports:

  • 1997
  • 1998
  • 1999 Progress Report
  • Final

  • Main Center Abstract and Reports:

    R825433    EERC - Center for Ecological Health Research (Cal Davis)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R825433C001 Potential for Long-Term Degradation of Wetland Water Quality Due to Natural Discharge of Polluted Groundwater
    R825433C002 Sacramento River Watershed
    R825433C003 Endocrine Disruption in Fish and Birds
    R825433C004 Biomarkers of Exposure and Deleterious Effect: A Laboratory and Field Investigation
    R825433C005 Fish Developmental Toxicity/Recruitment
    R825433C006 Resolving Multiple Stressors by Biochemical Indicator Patterns and their Linkages to Adverse Effects on Benthic Invertebrate Patterns
    R825433C007 Environmental Chemistry of Bioavailability in Sediments and Water Column
    R825433C008 Reproduction of Birds and mammals in a terrestrial-aquatic interface
    R825433C009 Modeling Ecosystems Under Combined Stress
    R825433C010 Mercury Uptake by Fish
    R825433C011 Clear Lake Watershed
    R825433C012 The Role of Fishes as Transporters of Mercury
    R825433C013 Wetlands Restoration
    R825433C014 Wildlife Bioaccumulation and Effects
    R825433C015 Microbiology of Mercury Methylation in Sediments
    R825433C016 Hg and Fe Biogeochemistry
    R825433C017 Water Motions and Material Transport
    R825433C018 Economic Impacts of Multiple Stresses
    R825433C019 The History of Anthropogenic Effects
    R825433C020 Wetland Restoration
    R825433C021 Sierra Nevada Watershed Project
    R825433C022 Regional Transport of Air Pollutants and Exposure of Sierra Nevada Forests to Ozone
    R825433C023 Biomarkers of Ozone Damage to Sierra Nevada Vegetation
    R825433C024 Effects of Air Pollution on Water Quality: Emission of MTBE and Other Pollutants From Motorized Watercraft
    R825433C025 Regional Movement of Toxics
    R825433C026 Effect of Photochemical Reactions in Fog Drops and Aerosol Particles on the Fate of Atmospheric Chemicals in the Central Valley
    R825433C027 Source Load Modeling for Sediment in Mountainous Watersheds
    R825433C028 Stress of Increased Sediment Loading on Lake and Stream Function
    R825433C029 Watershed Response to Natural and Anthropogenic Stress: Lake Tahoe Nutrient Budget
    R825433C030 Mercury Distribution and Cycling in Sierra Nevada Waterbodies
    R825433C031 Pre-contact Forest Structure
    R825433C032 Identification and distribution of pest complexes in relation to late seral/old growth forest structure in the Lake Tahoe watershed
    R825433C033 Subalpine Marsh Plant Communities as Early Indicators of Ecosystem Stress
    R825433C034 Regional Hydrogeology and Contaminant Transport in a Sierra Nevada Ecosystem
    R825433C035 Border Rivers Watershed
    R825433C036 Toxicity Studies
    R825433C037 Watershed Assessment
    R825433C038 Microbiological Processes in Sediments
    R825433C039 Analytical and Biomarkers Core
    R825433C040 Organic Analysis
    R825433C041 Inorganic Analysis
    R825433C042 Immunoassay and Serum Markers
    R825433C043 Sensitive Biomarkers to Detect Biochemical Changes Indicating Multiple Stresses Including Chemically Induced Stresses
    R825433C044 Molecular, Cellular and Animal Biomarkers of Exposure and Effect
    R825433C045 Microbial Community Assays
    R825433C046 Cumulative and Integrative Biochemical Indicators
    R825433C047 Mercury and Iron Biogeochemistry
    R825433C048 Transport and Fate Core
    R825433C049 Role of Hydrogeologic Processes in Alpine Ecosystem Health
    R825433C050 Regional Hydrologic Modeling With Emphasis on Watershed-Scale Environmental Stresses
    R825433C051 Development of Pollutant Fate and Transport Models for Use in Terrestrial Ecosystem Exposure Assessment
    R825433C052 Pesticide Transport in Subsurface and Surface Water Systems
    R825433C053 Currents in Clear Lake
    R825433C054 Data Integration and Decision Support Core
    R825433C055 Spatial Patterns and Biodiversity
    R825433C056 Modeling Transport in Aquatic Systems
    R825433C057 Spatial and Temporal Trends in Water Quality
    R825433C058 Time Series Analysis and Modeling Ecological Risk
    R825433C059 WWW/Outreach
    R825433C060 Economic Effects of Multiple Stresses
    R825433C061 Effects of Nutrients on Algal Growth
    R825433C062 Nutrient Loading
    R825433C063 Subalpine Wetlands as Early Indicators of Ecosystem Stress
    R825433C064 Chlorinated Hydrocarbons
    R825433C065 Sierra Ozone Studies
    R825433C066 Assessment of Multiple Stresses on Soil Microbial Communities
    R825433C067 Terrestrial - Agriculture
    R825433C069 Molecular Epidemiology Core
    R825433C070 Serum Markers of Environmental Stress
    R825433C071 Development of Sensitive Biomarkers Based on Chemically Induced Changes in Expressions of Oncogenes
    R825433C072 Molecular Monitoring of Microbial Populations
    R825433C073 Aquatic - Rivers and Estuaries
    R825433C074 Border Rivers - Toxicity Studies