Aquatic Sciences Meeting, Albuquerque 2001

SS40 Long-Term Research Programs in the Twenty-first Century (Spatial and Temporal Connections)

Date: Thursday, February 15, 2001, Time: 2:00:00 PM

Location: Ruidoso/Pecos

Nelson, D, C, Microbiology, Univ. California, Davis, USA, dcnelson@ucdavis.edu

Suchanek, T, H, Wildlife, Fish and Conservation Biol., Univ. California, Davis, USA, thsuchanek@ucdavis.edu

Zierenberg, R, A, Geology, Univ. California, Davis, USA, zierenberg@geology.ucdavis.edu

Shipp, W, G, Geology, Univ. California, Davis, USA,

Fleming, E, J, Microbiology, Univ. California, Davis, USA,

Mack, E, E, Microbiology, Univ California, Davis, USA,

GROUNDWATER FLOWS LINK ABANDONED MERCURY MINE AT CLEAR LAKE, CA, WITH MICROBIAL PRODUCTION OF METHYLMERCURY AND ACCUMULATION IN BIOTA.

Clear Lake, the largest freshwater lake entirely within California, has sediments and biota that are heavily contaminated with mercury that originates from the Sulphur Bank Mercury Mine. Concentrations of inorganic mercury in lake-sediments near the mine can exceed 400 ppm, while methylmercury in top carnivores can exceed 1 ppm. A major feature of this abandoned mine is the Herman Pit (30 m deep, 23 acres surface area), which is situated 200 m from the Oaks Arm shoreline. It is filled with acid mine drainage (pH 3.0, sulfate 20 mM) and has a hydrostatic head of 4 m above lake level. Recent porewater analyses indicate that diffusive and advective subsurface flows from the mine site impact lake sediments along a minimum of 400 m of shoreline and extend lakeward at least 75 m. The sites most heavily impacted by these flows are also most active in microbial production of methylmercury and its export to the water column. Additional seasonal and spatial monitoring and modeling will be required to quantify key mercury linkages between the mine site, sediment porewaters and lake biota.

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Aquatic Sciences Meeting, Albuquerque 2001

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