IIg-Contaminated Industrial and Mining Sites in N. America
99
2.6
Onondaga Lake, Syracuse, New York
This alkaline, eutrophic lake received waste effluents from a variety of chemical
plants and the city of Syracuse, NY, for more than a century. A chloralkali plant
operated on the shores of the lake between 1947 and 1988, releasing an estimated
75 Mg of mercury to the lake over this period. The biogeochemistry of mercury
in this lake has been investigated extensively and many publications are available
(e.g., Bloom and Effler 1990; Wang and Driscoll 1995; Jacobs et al. 1995; Becker
and Bigham 1995; Henry et al. 1995a, b; Bigham and Vandal 1996; Effler 1996).
The temporal record (Effler 1996; Bigham and Vandal 1996) of mercury in fish in
this lake illustrates an enigmatic pattern sometimes observed elsewhere (see also
Oak Ridge and Saltville) in aquatic systems subjected to high mercury discharges
which are subsequently greatly reduced: initial rapid decreases followed by
leveling off at still elevated concentrations and even increases in concentrations
while mercury inputs are still decreasing. This site also nicely illustrates a case
where contaminated sediments were long suspected to be largely, or entirely,
responsible for slow or incomplete restoration of fish concentrations to safe
levels. Detailed studies and modeling eventually demonstrated that "although the
sediments of Onondaga Lake contain an enormous mass of total Hg at depth,
they are a net sink rather than a source for both total Hg and CH3Hg to the lake"
(Henry et al. 1995a).
2.7
Wabigoon/English/Winnipeg River System, Ontario
This site is perhaps the best-studied example in the world of an aquatic system
highly contaminated with mercury from a chloralkali plant and associated wood
pulp mill (e.g., Fimreite and Reynolds 1973; Armstrong and Hamilton 1973;
Annett et al. 1975; Armstrong and Scott 1979; Jackson and Woychuk 1980;
Jackson et al. 1982; Allan et al. 1984; Rudd et al. 1983; Parks et al. 1986, 1989, 1991;
Parks and Hamilton 1987). This plant operated from 1963 until 1975 with an
estimated loss of mercury to the river of about lO t. Some of the highest
concentrations of mercury ever reported for freshwater fish (northern pike:
27.8 ~lg g-', walleye: 19.6 ~lg g-', burbot: 24.8 g-') were measured at this site
(summarized in Annett et al. 1975). The history of releases of mercury from this
plant are nicely recorded in sediments in Clay Lake, where successive corings
have shown the peak being gradually covered by cleaner sediment (W.L.
Lockhart, pers. comm.). In spite of this evidence of burial of mercury from
historic releases, mercury in fish has not returned to levels allowing lifting of
consumption advisories. For example, in 1990, walleye from Clay Lake still
averaged over 2 pg g-', four times higher than the Canadian human health limit.
Detailed studies of geographical patterns in mercury in this system revealed
some apparent anomalies. For example, Parks et al. (1991) noted that while the
overall trend for the entire system shows that mercury concentrations in biota
decrease with distance downstream from the former mercury source, this was not
99
2.6
Onondaga Lake, Syracuse, New York
This alkaline, eutrophic lake received waste effluents from a variety of chemical
plants and the city of Syracuse, NY, for more than a century. A chloralkali plant
operated on the shores of the lake between 1947 and 1988, releasing an estimated
75 Mg of mercury to the lake over this period. The biogeochemistry of mercury
in this lake has been investigated extensively and many publications are available
(e.g., Bloom and Effler 1990; Wang and Driscoll 1995; Jacobs et al. 1995; Becker
and Bigham 1995; Henry et al. 1995a, b; Bigham and Vandal 1996; Effler 1996).
The temporal record (Effler 1996; Bigham and Vandal 1996) of mercury in fish in
this lake illustrates an enigmatic pattern sometimes observed elsewhere (see also
Oak Ridge and Saltville) in aquatic systems subjected to high mercury discharges
which are subsequently greatly reduced: initial rapid decreases followed by
leveling off at still elevated concentrations and even increases in concentrations
while mercury inputs are still decreasing. This site also nicely illustrates a case
where contaminated sediments were long suspected to be largely, or entirely,
responsible for slow or incomplete restoration of fish concentrations to safe
levels. Detailed studies and modeling eventually demonstrated that "although the
sediments of Onondaga Lake contain an enormous mass of total Hg at depth,
they are a net sink rather than a source for both total Hg and CH3Hg to the lake"
(Henry et al. 1995a).
2.7
Wabigoon/English/Winnipeg River System, Ontario
This site is perhaps the best-studied example in the world of an aquatic system
highly contaminated with mercury from a chloralkali plant and associated wood
pulp mill (e.g., Fimreite and Reynolds 1973; Armstrong and Hamilton 1973;
Annett et al. 1975; Armstrong and Scott 1979; Jackson and Woychuk 1980;
Jackson et al. 1982; Allan et al. 1984; Rudd et al. 1983; Parks et al. 1986, 1989, 1991;
Parks and Hamilton 1987). This plant operated from 1963 until 1975 with an
estimated loss of mercury to the river of about lO t. Some of the highest
concentrations of mercury ever reported for freshwater fish (northern pike:
27.8 ~lg g-', walleye: 19.6 ~lg g-', burbot: 24.8 g-') were measured at this site
(summarized in Annett et al. 1975). The history of releases of mercury from this
plant are nicely recorded in sediments in Clay Lake, where successive corings
have shown the peak being gradually covered by cleaner sediment (W.L.
Lockhart, pers. comm.). In spite of this evidence of burial of mercury from
historic releases, mercury in fish has not returned to levels allowing lifting of
consumption advisories. For example, in 1990, walleye from Clay Lake still
averaged over 2 pg g-', four times higher than the Canadian human health limit.
Detailed studies of geographical patterns in mercury in this system revealed
some apparent anomalies. For example, Parks et al. (1991) noted that while the
overall trend for the entire system shows that mercury concentrations in biota
decrease with distance downstream from the former mercury source, this was not