98
R.R. Turner and G.R. Southworth
birds (up to 17 ~lg g-I in liver of red-necked grebe) collected during the second
mining period. Since mining activity ended in 1975, mercury in fish has
declined substantially but the lake is still under a fishing advisory (Martin
et al. 1995). Siegel et al. (1985) compared mercury in soil and plants near this
mine with regional and larger patterns to try to distinguish Hg background
values from mining-enhanced values. They concluded that effects of mining
seemed to be intense but localized to the vicinity of the mine. Abelson and
Gustavson (1979) also compared water quality and sediments in Pinchi Lake
with nearby lakes not impacted by mining. No corrective actions beyond those
associated with the last period of mining are known to have been undertaken
at the site.
2.S
Clear Lake, California
Although somewhat larger (177 km
2 ) than Pinchi Lake, Clear Lake in northern
California also received direct inputs of mercury mining wastes in one relatively
small area (Oaks Arm) due to episodic cinnabar mining spanning nearly a
century. The last activity ceased in 1957 after 4700 Mg of mercury had been
produced from the site with an estimated 100 Mg being deposited in the lake
(Suchanek et al. 1993, 1995). The site has been under investigation as a CERCLA
site and has already experienced some minor corrective action (completed in
1992) directed at stabilization of mine wastes along the shoreline. Gill and
Bruland (1990) measured mercury at several locations in this lake in 1987 and
reported finding the highest concentrations (about 100 ng I-I), with most in the
particulate fraction, close to the mine site. Total mercury ranged from about 4 to
20 ng I-I elsewhere in the lake. Suchanek et al. (1995) reported that total mercury
in sediment (0.27 to 183 ~lg g-I) and in benthic invertebrates « 0.5 to 42 pg g-I)
decreases systematically (linearly or exponentially) with distance from the mine.
Although contamination of fish in the lake has not been exceptionally high in
recent years (most predacious fish are below 1.0 ~lg g-I), the lake remains under
a fish consumption advisory. Patterns of mercury in water and biota (plankton
and fish) as a function of distance from the mine site have been somewhat
enigmatic in showing either no trend or increased concentrations with increasing
distance from the mine. Pisciverous wildlife has been monitored for evidence of
both contamination with mercury (using feathers, fur, tissues, blood) and nesting
success (Suchanek et al. 1997; Elbert and Anderson 1998; Wolfe and Norman
1998). The most recent information does not suggest that these receptors are
currently affected by mercury, although older data suggest that some may have
been prior to stabilization of the shoreline in 1992. The focus of ongoing
investigative work at the lake has recently shifted from the inventory of mercury
contained in lake sediments to acidic groundwater inputs of mercury from the
mine site which appear to be more important in sustaining surface sediment
contamination (Suchanek et al. 1997).
R.R. Turner and G.R. Southworth
birds (up to 17 ~lg g-I in liver of red-necked grebe) collected during the second
mining period. Since mining activity ended in 1975, mercury in fish has
declined substantially but the lake is still under a fishing advisory (Martin
et al. 1995). Siegel et al. (1985) compared mercury in soil and plants near this
mine with regional and larger patterns to try to distinguish Hg background
values from mining-enhanced values. They concluded that effects of mining
seemed to be intense but localized to the vicinity of the mine. Abelson and
Gustavson (1979) also compared water quality and sediments in Pinchi Lake
with nearby lakes not impacted by mining. No corrective actions beyond those
associated with the last period of mining are known to have been undertaken
at the site.
2.S
Clear Lake, California
Although somewhat larger (177 km
2 ) than Pinchi Lake, Clear Lake in northern
California also received direct inputs of mercury mining wastes in one relatively
small area (Oaks Arm) due to episodic cinnabar mining spanning nearly a
century. The last activity ceased in 1957 after 4700 Mg of mercury had been
produced from the site with an estimated 100 Mg being deposited in the lake
(Suchanek et al. 1993, 1995). The site has been under investigation as a CERCLA
site and has already experienced some minor corrective action (completed in
1992) directed at stabilization of mine wastes along the shoreline. Gill and
Bruland (1990) measured mercury at several locations in this lake in 1987 and
reported finding the highest concentrations (about 100 ng I-I), with most in the
particulate fraction, close to the mine site. Total mercury ranged from about 4 to
20 ng I-I elsewhere in the lake. Suchanek et al. (1995) reported that total mercury
in sediment (0.27 to 183 ~lg g-I) and in benthic invertebrates « 0.5 to 42 pg g-I)
decreases systematically (linearly or exponentially) with distance from the mine.
Although contamination of fish in the lake has not been exceptionally high in
recent years (most predacious fish are below 1.0 ~lg g-I), the lake remains under
a fish consumption advisory. Patterns of mercury in water and biota (plankton
and fish) as a function of distance from the mine site have been somewhat
enigmatic in showing either no trend or increased concentrations with increasing
distance from the mine. Pisciverous wildlife has been monitored for evidence of
both contamination with mercury (using feathers, fur, tissues, blood) and nesting
success (Suchanek et al. 1997; Elbert and Anderson 1998; Wolfe and Norman
1998). The most recent information does not suggest that these receptors are
currently affected by mercury, although older data suggest that some may have
been prior to stabilization of the shoreline in 1992. The focus of ongoing
investigative work at the lake has recently shifted from the inventory of mercury
contained in lake sediments to acidic groundwater inputs of mercury from the
mine site which appear to be more important in sustaining surface sediment
contamination (Suchanek et al. 1997).