Investigations and Monitoring of Mercury in Indiana

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Starting in 2000, the U.S. Geological Survey partnered with the Indiana Department of Environmental Management, the National Atmospheric Deposition Program, and the Lake Michigan Air Directors Consortium to investigate and monitor mercury in the environment in Indiana. This web page provides a list of publications and links to statewide studies of mercury in Indiana and regional mercury studies that include Indiana. The list is grouped by three topics: mercury in precipitation, dry deposition of atmospheric mercury, and mercury in surface water. Additional mercury information from the USGS..... 

Mercury is a persistent toxic pollutant that poses a risk to humans and wildlife, primarily through fish consumption. Small concentrations of inorganic mercury that are transported to streams, lakes, and wetlands by precipitation, dry atmospheric deposition, and wastewater discharges can be converted to organic methylmercury. Methylmercury accumulates in the food chain and magnifies in concentration going up the chain. Humans and wild mammals and birds at the top level can be exposed to methylmercury concentrations that are high enough to pose a health risk. Methylmercury can cause damage to the brain and nervous system, especially in the young and unborn. In some wildlife, reproduction can be affected.

 

Mercury in Precipitation

Precipitation sampler
    Automated sampler for mercury in precipitation

Mercury in precipitation in Indiana was monitored by the USGS from 2000 through 2010 in cooperation with the Indiana Department of Environmental Management and by the Lake Michigan Air Directors Consortium from 2010 through 2017. Monitoring stations are part of the National Atmospheric Deposition Program Mercury Deposition Network which provides a free, on-line data archive. 

Mercury in precipitation was monitored during 2004-2005 at five locations in Indiana as part of the National Atmospheric Deposition Program-Mercury Deposition Network (NADP-MDN). Monitoring stations were operated at Roush Lake near Huntington, Clifty Falls State Park near Madison, Fort Harrison State Park near Indianapolis, Monroe County Regional Airport near Bloomington, and Indiana Dunes National Lakeshore near Porter. At these monitoring stations, precipitation amounts were measured continuously and weekly samples were collected for analysis of mercury by methods achieving detection limits as low as 0.05 ng/L (nanograms per liter). 

Mercury in precipitation was monitored during 2001 through 2003 at four locations in Indiana as part of the National Atmospheric Deposition Program-Mercury Deposition Network (NADP-MDN). Monitoring stations were operated at Roush Lake near Huntington, Clifty Falls State Park near Madison, Monroe County Regional Airport near Bloomington, and Indiana Dunes National Lakeshore near Porter. At these monitoring stations, precipitation amounts were measured and weekly samples were collected for analysis of total mercury and methylmercury by low-level methods. 

 

Map of average annual mercury wet deposition - Great Lakes
      Map of average annual mercury wet deposition

 

Annual and weekly mercury (Hg) concentrations, precipitation depths, and Hg wet deposition in the Great Lakes region were analyzed by using data from 5 monitoring networks in the USA and Canada for a 2002-2008 study period. High-resolution maps of calculated annual data, 7-year mean data, and net interannual change for the study period were prepared to assess spatial patterns.

As many as 51 mercury (Hg) wet-deposition-monitoring sites from 4 networks were operated in 8 USA states and Ontario, Canada in the North American Great Lakes Region from 1996 to 2010. By 2013, 20 of those sites were no longer in operation and approximately half the geographic area of the Region was represented by a single Hg-monitoring site. In response, a Great Lakes Atmospheric Mercury Monitoring (GLAMM) network is needed as a framework for regional collaboration in Hg-deposition monitoring. The purpose of the GLAMM network is to detect changes in regional atmospheric Hg deposition related to changes in Hg emissions.

 

Litterfall and throughfall monitoring for mercury dry deposition
Litterfall and throughfall monitoring for mercury dry deposition

Dry Deposition of Atmospheric Mercury

Dry deposition of atmospheric mercury can be estimated with surface-air concentrations of mercury measured with manual or automated methods. A manual method was used in Indiana in 2004. The automated method was used at a National Atmospheric Deposition Atmospheric Mercury Network site in Indiana, starting in 2016.  Dry deposition of atmospheric mercury to forest landscapes was measured by the U.S. Geological Survey in litterfall during 2007-2009 and 2012-2016 as part of a National Atmospheric Deposition Program litterfall network.

Measurement of Atmospheric Mercury Species with Manual Sampling and Analysis Methods in a Case Study in Indiana

Ground-level concentrations of three atmospheric mercury species were measured using manual sampling and analysis to provide data for estimates of mercury dry deposition. Three monitoring stations were operated simultaneously during winter, spring, and summer 2004, adjacent to three mercury wet-deposition monitoring stations in northern, central, and southern Indiana. The monitoring locations differed in land-use setting and annual mercury-emissions level from nearby sources. A timer-controlled air-sampling system that contained a three-part sampling train was used to isolate reactive gaseous mercury, particulate-bound mercury, and elemental mercury. The sampling trains were exchanged every 6 days, and the mercury species were quantified in a laboratory.

Mercury in Litterfall at Selected National Atmospheric Deposition Program Mercury Deposition Network Sites, 2007--2009

Mercury (Hg) in autumn litterfall from predominately deciduous forests was measured in 3 years of samples from 23 Mercury Deposition Network sites in 15 states across the eastern USA. Annual litterfall Hg dry deposition was significantly higher (median 12.3 micrograms per square meter (μg/m2), range 3.5–23.4 μg/m2) than annual Hg wet deposition (median 9.6 μg/m2, range 4.4–19.7 μg/m2).

 

Mercury in Surface Water

Mercury in surface water Indiana was investigated by the U.S. Geological Survey during 2001-2009, including studies of streams and reservoirs. 

 

Sampling system for for collecting lake water for mercury analysis
Sampling system for for collecting lake water for mercury analysis

 

Mercury and Methylmercury in Reservoirs in Indiana

Mercury (Hg) is an element that occurs naturally, but evidence suggests that human activities have resulted in increased amounts being released to the atmosphere and land surface. When Hg is converted to methylmercury (MeHg) in aquatic ecosystems, MeHg accumulates and increases in the food web so that some fish contain levels which pose a health risk to humans and wildlife that consume these fish. Reservoirs unlike natural lakes, are a part of river systems that are managed for flood control. Data compiled and interpreted for six flood-control reservoirs in Indiana showed a relation between Hg transport, MeHg formation in water, and MeHg in fish that was influenced by physical, chemical, and biological differences among the reservoirs. Existing information precludes a uniform comparison of Hg and MeHg in all reservoirs in the State, but factors and conditions were identified that can indicate where and when Hg and MeHg levels in reservoirs could be highest.

Mercury in Indiana Watersheds: Retrospective for 2001-2006

Information about total mercury and methylmercury concentrations in water samples and mercury concentrations in fish-tissue samples was summarized for 26 watersheds in Indiana that drain most of the land area of the State. Mercury levels were interpreted with information on streamflow, atmospheric mercury deposition, mercury emissions to the atmosphere, mercury in wastewater, and landscape characteristics.

Isokinetic sampler on bridge crane
Collecting stream water for mercury analysis with isokinetic sampler from a bridge

Total Mercury and Methylmercury in Indiana Streams, August 2004-- September 2006

Total mercury and methylmercury were determined by use of low (subnanogram per liter) level analytical methods in 225 representative water samples collected following ultraclean protocols at 25 Indiana monitoring stations in a statewide network, on a seasonal schedule, August 2004-September 2006. The highest unfiltered total mercury concentrations were at six monitoring stations - five that are downstream from urban and industrial wastewater discharges and that have upstream drainage areas more than 1,960 square miles and one that is downstream from active and abandoned mine lands and that has an upstream drainage area of 602 square miles.

Mercury in the Grand Calumet River/Indiana Harbor Canal and Lake Michigan, Lake County, Indiana, August 2001 and May 2002

Water samples from the Grand Calumet River/Indiana Harbor Canal and Lake Michigan in Lake County, Indiana, were collected and analyzed for mercury. Sampling was done with ultra-clean protocols, and mercury was analyzed by low-level methods during seasons of contrasting weather and streamflow conditions in August 2001 and May 2002.