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National Assessment of Mercury in Aquatic Ecosystems
 Recent
dramatic increases in mercury fish-consumption advisories that now occur
in 40 states demonstrate that mercury is a serious national problem. Aquatic
ecosystems across the Nation are being studied to identify the factors
that control where and when mercury accumulates to toxic levels in the
food chain. Ecosystems with varying source intensity (mining, natural,
and atmospheric sources, and varying potential to convert mercury to its
most toxic form, methylmercury, are being tested.
- A synoptic sampling of water, sediment, and fish has been conducted
at 112 sites across the Nation. The samples were analyzed for mercury
and the more toxic form of mercury, methylmercury. Regulatory agencies
have struggled to understand whether specific ecosystem types or specific
regions of the U.S. are more susceptible to mercury loading. Results
from this study are some of the first available information to help
guide these decisions.
- An additional part of the mercury assessment is determining if the
widespread mercury problem is a result of current mercury emissions
into the atmosphere or if it is due to "old" mercury that is already
in the environment. The answers to these questions could help regulators
determine what the response of ecosystems will be, in terms of reduced
exposure levels to humans and wildlife, if emissions of mercury are
reduced. The U.S. Environmental Protection Agency and the U.S. Department
of Energy currently estimate that emission controls for mercury would
cost approximately $2 billion a year to operate. The scientific community's
current understanding of the fate of mercury in the environment cannot
guarantee or provide reasonable assurance that significant environmental
improvements would result from reduced emissions of mercury. To address
this important question, an international team of researchers that includes
scientists from the USGS has been given permission by the Canadian government
to add specific mercury isotopes to an entire watershed. This experiment
is called METAALICUS
(Mercury experiment to assessatmospheric loading in Canada and the united
States). The results of this experiment will allow the research team
to determine precisely how much and how quickly recently added mercury
enters food webs.
- The final part of mercury assessment is to provide information on
the hydrological, biological, and geochemical processes controlling
mercury cycling in the Everglades National Park, Florida, for the USGS
Aquatic Cycling
of Mercury in the Everglades (ACME) project. The ACME project is
an interagency study with the objective of providing information on
mercury cycling in the Everglades that can be used to simulate restoration
alternatives and predict potential outcomes. The ACME project is part
of the larger South Florida Ecosystem
Program that has the objective of providing the scientific information
needed for the Department of the Interior's effort to restore, to the
extent possible, the predevelopment conditions of water flow and the
health of the ecosystem in the Everglades.
Other USGS Mercury Activities
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