Link to USGS home page.
red line
Western Lake Michigan Drainages NAWQA Study Unit title graphic

corner piece   corner piece
  Mercury  
   
 

 

 

What we hope to answer with the USGS National Mercury Bioaccumulation Study?

  1. Determine the effects of mercury loading from sources (such as coal-fired energy plants), mercury methylation efficiency (how efficiently certain bacteria in some ecosystems change other forms of mercury into methyl mercury), and food web interactions (algae, aquatic insects, and fish as food sources) on the bioaccumulation of mercury in predator fish.
  2. Quantify the source and seasonality of mercury and methyl mercury as well as biogeochemical species and transformation rates related to the aquatic mercury cycle.

Background

The USGS National Water Quality Assessment program and Toxic Substances Hydrology program are conducting a national study of mercury in different rivers of the US. Mercury is a toxic chemical that can cause neurological damage in people. The most common way that people get mercury in their bodies is by eating fish that have been contaminated with the chemical. The source of mercury for most waters is airborne from coal-fired energy plants and this mercury falls on lakes, wetlands, and streams sometimes far from the source. Under just the right conditions, certain kinds of bacteria change this mercury into methyl mercury, the form most easily taken up by other organisms. Methyl mercury is the primary form in fish. Methyl mercury can increase in concentration from algae, stream invertebrates such as insects, to small fish, game fish, birds, and people. Many states have advisories about eating fish from their waters because of mercury concerns.

Facts About Mercury Red line
square Highly toxic to the nervous system

square Persistent in the environment

square Bioaccumulates (higher concentrations in tissues of aquatic plants)

square Biomagnifies (higher concentrations at increasingly higher levels in the food chain)

square Numerous chemical forms in air, water, sediment, and biota

square Responsible for nearly 80 percent of U.S. fish-consumption advisories
 

Photograph of smokestack [Phil Redman]Mercury Issues in Wisconsin

  • State agencies, tribes, environmental advocacy groups, and the public in Wisconsin have a relatively high level of concern regarding mercury.
  • The primary source for mercury contamination in Wisconsin waters is airborne from coal combustion, and the Wisconsin Department of Natural Resources has estimated that 50% of the mercury deposited in the state comes from within Wisconsin.
  • Nationwide, Wisconsin ranks second in the number of lakes and rivers with mercury advisories for fish consumption.
  • The Western Lake Michigan drainage is 15% wetland overall and 40-60% wetland in the northern part of the study unit. In addition to a high percentage of wetland, many of these streams are characterized by additional factors considered to be important in creating methyl mercury.

Click for map showing Mercury location sitesStudy Design

  • In 2002, fish, water, and sediment were sampled in 14 NAWQA study units nationwide
  • In 2003-4, more detailed sampling was done in three of these study units, including the Western Lake Michigan Drainages, Willamette River Basin in Oregon , and Georgia-Florida Coastal Plain. In each study unit, this sampling was done at 2-3 sites representing one urban and one to two rural/non-cultivated watersheds. Additional study units began similar mercury sampling in 2005.
  • In 2004-5, limited sampling for long-term trends in mercury concentrations began in the Western Lake Michigan Drainages, Willamette River Basin in Oregon , and Georgia-Florida Coastal Plain study units.

Approach

  • Stream sampling sites were selected based on the availability of target predator fish and mercury-source landscapes including urban and reference or non-cultivated.
  • Total mercury (all forms) and methyl mercury in water were sampled monthly plus during selected storm events in 2003-04.
  • Potential net methylation rates in sediment and mercury in pore water and sediment were measured seasonally.
  • Total mercury and stable carbon and nitrogen isotopes were determined in predator fish to examine the effect of food sources; total and methyl mercury and stable isotopes also were determined in food chain organisms (forage fish, invertebrates, and algae).
  • Data from the Mercury Deposition Network will be used to determine loading rates so that the amount of mercury entering the stream ecosystems can be assessed in relation to the amount of mercury accumulating in the water, sediment, and fish.

Table 1. Sites in Wisconsin sampled for the Mercury Topical, Mercury Synoptic and Mercury Trends Studies.

Station Name

Station Id. Code

Latitude

Longitude

Datum

Study

Year(s) of Sampling

Pine River near Tipler, WI

04063660

45° 53' 37"

88° 33' 31"

NAD27

Mercury Synoptic

2002

South Branch Oconto River near Breed, WI

04070720

45° 03' 40"

88° 31' 24"

NAD27

Mercury Synoptic

2002

Milwaukee River at Milwaukee, WI

04087000

43° 06' 00"

87° 54' 32"

NAD27

Mercury Synoptic

2002

Root River near Franklin, WI

04087220

42° 52' 25"

87° 59' 45"

NAD27

Mercury Synoptic

2002

Poplar Creek near Waukesha, WI

05543796

43° 02' 39"

88° 09' 59"

NAD27

Mercury Synoptic

2002

Popple River near Fence, WI

04063700

45° 45' 49"

88° 27' 47"

NAD27

Mercury Synoptic

2002

Mercury Trends

2004-present

Oak Creek at South Milwaukee, WI

04087204

42° 55' 30"

87° 52' 12"

NAD27

Mercury Synoptic

2002

Mercury Topical

2003-2004

Evergreen River below Evergreen Falls near Langlade, WI

04075365

45° 03' 57"

88° 40' 34"

NAD27

Mercury Synoptic

2002

Mercury Topical

2003-2004

Mercury Trends

2004-present

Pike River near Amberg, WI

04066500

45° 30' 00"

88° 00' 00"

NAD27

Mercury Topical

2003-2004

 

Study Sites in the Western Lake Michigan Drainages 3 Streams

  • Urban
    • Oak Creek in South Milwaukee, WI: 42% urban land and 8% wetland
  • Reference/Non-cultivated
    • Evergreen River near Langlade, WI: 77% forested land and 9% wetland
    • Pike River near Amberg , WI: 72% forested land and 18% wetland

Summary

The USGS mercury studies will provide a nationwide data set of total and methyl mercury in river ecosystems in a variety of geographic settings. This information will add considerably to basic data needs and an improved understanding of mercury chemistry in diverse landscapes. The detailed investigation will contribute toward a greater understanding of the many factors that control how methyl mercury is formed and its resulting bioaccumulation in aquatic organisms in streams and rivers.

For more information on national mercury studies, see Fact Sheet 016-03 - Mercury in Stream Ecosystems: New Studies Initiated by the U.S. Geological Survey.

top

 
corner piece   corner piece
Home
Surface Water and Ecology
Ground Water
Mercury
Urbanization Effects
WMIC Publications
WMIC Data
 
WMIC Data - Background - WMIC Publications - Personnel
National NAWQA - NAWQA Glossary - Wisconsin Water Science Center
red line
USA.gov logo  Take Pride in America button