530
Related to the food–water nexus, excessive inputs of phosphorus from agricultural runoff have resulted in eutrophication and algal growth in some areas of the
Great Lakes. Efforts that began in the 1970s to reduce phosphorus loadings were
largely successful, but in some locations, phosphorus loads have been increasing
again, and an increasing share of the phosphorus is a dissolved form that is biologically available to fuel nearshore algal blooms (EC and EPA 2009).
Contaminated sediments are a significant and persistent threat to the Great Lakes
basin. Although the discharge of toxic chemicals to the Great Lakes has declined in
recent decades, persistent high concentrations of contaminated sediments in the bottoms of rivers and harbors pose potential risks to aquatic organisms, wildlife, and
humans (EPA 2016). Degraded harbor and tributary areas in the Great Lakes basin
have been identified and labeled as Areas of Concern (AOCs). The Great Lakes
Water Quality Agreement between the USA and Canada defines AOCs as areas
where significant impairment of beneficial uses has occurred as a result of human
activities at the local level (GLWQP 2012).
The problem of these buried contaminated sediments is a legacy of decades of
urban and agricultural non-point source runoff, industrial and municipal discharges,
and combined sewer overflows, all with some linkages to the food–energy–water
nexus. To address these impairments, each AOC developed a Remedial Action Plan
that identifies contaminated bottom sediments as a significant problem that must be
addressed to restore beneficial uses (EPA 2016).
Since the 1970s, concentrations of historically regulated contaminants such as
polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), and
mercury have generally declined in most monitored fish species. However, mercury
levels in fish have been slowly increasing since 1990, after years of steady decline
(EC and EPA 2009). Atmospheric deposition from coal-powered power plant and
municipal waste incinerator emissions is the largest source of mercury pollution to
the Great Lakes. Emissions from coal-fired power plants attributed to as much as
57% of the mercury pollution (Evers et al. 2011).
Mercury in the environment does not break down over time, and due to its bioaccumulative nature, even small concentrations of mercury in water can have large
impacts on food webs. Mercury concentrations can be magnified by one to ten million times in fish and fish-eating birds like loons, reducing their growth and reproductive success (Evers et al. 2011).
At the energy–water nexus, increasing biofuels production, decommissioning of
coal power plants, and shifts to nuclear energy are changing the stresses on the
water in the Great Lakes. This is complicated by particular invasive species that
have different effects on the lakes, including Zebra mussels clogging water pipes
and lampreys altering fish populations.
Additionally, legacy toxic contamination associated with the history of industrial
activity in the region remains a problem, and the US states and Canadian provinces
continue to work toward resolving these issues under the Binational Toxics Strategy,
adopted in 1997.
R. B. Richardson
Related to the food–water nexus, excessive inputs of phosphorus from agricultural runoff have resulted in eutrophication and algal growth in some areas of the
Great Lakes. Efforts that began in the 1970s to reduce phosphorus loadings were
largely successful, but in some locations, phosphorus loads have been increasing
again, and an increasing share of the phosphorus is a dissolved form that is biologically available to fuel nearshore algal blooms (EC and EPA 2009).
Contaminated sediments are a significant and persistent threat to the Great Lakes
basin. Although the discharge of toxic chemicals to the Great Lakes has declined in
recent decades, persistent high concentrations of contaminated sediments in the bottoms of rivers and harbors pose potential risks to aquatic organisms, wildlife, and
humans (EPA 2016). Degraded harbor and tributary areas in the Great Lakes basin
have been identified and labeled as Areas of Concern (AOCs). The Great Lakes
Water Quality Agreement between the USA and Canada defines AOCs as areas
where significant impairment of beneficial uses has occurred as a result of human
activities at the local level (GLWQP 2012).
The problem of these buried contaminated sediments is a legacy of decades of
urban and agricultural non-point source runoff, industrial and municipal discharges,
and combined sewer overflows, all with some linkages to the food–energy–water
nexus. To address these impairments, each AOC developed a Remedial Action Plan
that identifies contaminated bottom sediments as a significant problem that must be
addressed to restore beneficial uses (EPA 2016).
Since the 1970s, concentrations of historically regulated contaminants such as
polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), and
mercury have generally declined in most monitored fish species. However, mercury
levels in fish have been slowly increasing since 1990, after years of steady decline
(EC and EPA 2009). Atmospheric deposition from coal-powered power plant and
municipal waste incinerator emissions is the largest source of mercury pollution to
the Great Lakes. Emissions from coal-fired power plants attributed to as much as
57% of the mercury pollution (Evers et al. 2011).
Mercury in the environment does not break down over time, and due to its bioaccumulative nature, even small concentrations of mercury in water can have large
impacts on food webs. Mercury concentrations can be magnified by one to ten million times in fish and fish-eating birds like loons, reducing their growth and reproductive success (Evers et al. 2011).
At the energy–water nexus, increasing biofuels production, decommissioning of
coal power plants, and shifts to nuclear energy are changing the stresses on the
water in the Great Lakes. This is complicated by particular invasive species that
have different effects on the lakes, including Zebra mussels clogging water pipes
and lampreys altering fish populations.
Additionally, legacy toxic contamination associated with the history of industrial
activity in the region remains a problem, and the US states and Canadian provinces
continue to work toward resolving these issues under the Binational Toxics Strategy,
adopted in 1997.
R. B. Richardson