1kuwabara@usgs.gov, U.S. Geological Survey, Menlo Park, CA
2btopping@usgs.gov, U.S. Geological Survey, Menlo Park, CA
3gemoon@usgs.gov, U.S. Geological Survey, Menlo Park, CA
4Husby.Peter@epamail.epa.gov, U.S. Environmental Protection Agency, Richmond, CA
5Lincoff.Andy@epamail.epa.gov, U.S. Environmental Protection Agency, Richmond, CA
6jlcarter@usgs.gov, U.S. Geological Survey, Menlo Park, CA
7mcroteau@usgs.gov, U.S. Geological Survey, Menlo Park, CA
The water columns of four reservoirs (Almaden, Calero, Guadalupe and Lexington Reservoirs) and an abandoned quarry pit filled by Alamitos Creek drainage for recreational purposes (Lake Almaden) were sampled on September 14 and 15, 2004 to provide the first measurements of mercury accumulation by phytoplankton and zooplankton in lentic systems (bodies of standing water, as in lakes and reservoirs) within the Guadalupe River watershed, California. Because of widespread interest in ecosystem effects associated with historic mercury mining within and downgradient of the Guadalupe Riverwatershed, transfer of mercury to lower trophic-level organisms was examined. The propensity of mercury to bioaccumulate, particularly in phytoplankton and zooplankton at the base of the food web, motivated this attempt to provide information in support of developing trophic-transfer and solute-transport models for the watershed, and hence in support of subsequent evaluation of load-allocation strategies. Both total mercury and methylmercury were examined in these organisms.
During a single sampling event, replicate samples from the reservoir water column were collected and processed for dissolved-total mercury, dissolved-methylmercury, phytoplankton mercury speciation, phytoplankton taxonomy and biomass, zooplankton mercury speciation, and zooplankton taxonomy and biomass. The timing of this sampling event was coordinated with sampling and analysis of fish from these five water bodies, during a period of the year when vertical stratification in the reservoirs generates a primary source of methylmercury to the watershed. Ancillary data, including dissolved organic carbon and trace-metal concentrations as well as vertical profiles of temperature, dissolved oxygen, specific conductance and pH, were gathered to provide a water-quality framework from which to compare the results for mercury. This work, in support of the Guadalupe River Mercury Total Maximum Daily Load (TMDL) Study, provides the first measurements of mercury trophic transfer through planktonic communities in this watershed. It is worth reemphasizing that this data set represents a single “snap shot” of conditions in water bodies within the Guadalupe River watershed to: (1) fill gaps in trophic transfer information, and (2) provide a scientific basis for future process-based studies with enhanced temporal and spatial coverage. This electronic document was unconventionally formatted to enhance the accessibility of information to a wide range of interest groups.
Executive Summary
Physical and Biological Characterizations
Chemical Characterizations
Potential Management Implications
Background
Results and Discussion
Physical Data
Biological Data
Chemical Data
Study Design and Methods
Water-column Sampling
Phytoplankton Sampling
Zooplankton Sampling
Small-fish Sampling
Chemical Parameters
References Cited
Acknowledgments
Appendix 1: Comments on the Report Structure
Appendix 2: Quality Control on Mercury-speciation Analyses
Appendix 3: List of Figures
Appendix 4: List of Tables
For additional information, contact:
James S. Kuwabara or Brent R. Topping
U.S. Geological Survey
345 Middlefield Road, MS 439
Menlo Park, CA 94025
Copies of this report may be obtained from the authors.
This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
Download the report (PDF, 8.6MB)
Document Accessibility: Adobe Systems Incorporated has information about PDFs and the visually impaired. This information provides tools to help make PDF files accessible. These tools convert Adobe PDF documents into HTML or ASCII text, which then can be read by a number of common screen-reading programs that synthesize text as audible speech. In addition, an accessible version of Acrobat Reader 5.0 for Windows (English only), which contains support for screen readers, is available. These tools and the accessible reader may be obtained free from Adobe at Adobe Access.
| AccessibilityFOIAPrivacyPolicies and Notices | |
  |
|