The University of Michigan Air Quality Laboratory Newsletter

The University of Michigan
School of Public Health
Department of Environmental and Industrial Health
109 S. Observatory
Ann Arbor, MI 48109
Phone: (313) 763-7714
Fax: (313) 764-9424

Atmospheric Mercury in the Great Lakes Region

Issue 1, Winter 1996

Air Quality Laboratory Begins Regional Study

The University of Michigan Air Quality Laboratory (UMAQL) has initiated a two-year study of atmospheric mercury in the Great Lakes region. The Great Lakes Atmospheric Mercury Assessment Project (GLAMAP) is jointly sponsored by the Great Lakes Protection Fund and the US EPA National Environmental Research Laboratory (NERL).

Project Goals

The UMAQL has two primary objectives for GLAMAP: (1) to establish a regional monitoring program for investigating the transport of and determining the source areas for atmospheric mercury in the Great Lakes region, (2) to facilitate cooperation among Great Lakes agencies and research groups to maintain this monitoring program. GLAMAP began in July 1994, with a workshop on atmospheric mercury where Great Lakes agencies and research groups worked together to finalize the plans for the monitoring network. Installation of the sampling equipment at the monitoring sites began in November 1994 with the last site operational in May 1995.

Monitoring Network

The atmospheric mercury monitoring network currently includes more than ten sites located throughout theGreat Lakes region, with most of the states and provinces that border the Great Lakes participating. Measurements of particle- and gas-phase mercury in ambient air are obtained on a routine basis concurrently at each of the sites (24-hour samples every 6th day). Total particulate samples are also collected on the same schedule for trace metal measurements.

UMAQL Measurements and Methods

Measurement: Particulate-phase Mercury
Method Description *: Open-face Teflon filter pack with glass fiber filter Extracted in 10% HNO3 with microwave digestion Analyzed by cold-vapor atomic fluorescence spectroscopy (CVAFS)

Measurement: Gas-phase Mercury
Method Description: Gold-coated glass bead traps analyzed by CVAFS

Measurement: Particulate Trace Metals
Method Description: Open-face Teflon filter pack with Teflon filter Analyzed by XRF at US EPA-NERL

UMAQL methods to be published in the US-EPA Compendium of Methods For Toxic Pollutants, 1996.

Great Lakes Agencies Meet at UMAQL Workshop

Representatives from federal, state and provincial agencies for the Great Lakes region met with scientists studying atmospheric mercury at a workshop held at the University of Michigan on July 7th and 8th, 1994. The goals of this workshop were to:

-finalize the monitoring program to assess atmospheric mercury levels in the Great Lakes region (i.e. sampling site locations),

-provide an overview of state-of-the-art mercury sampling and analysis techniques and ongoing mercury measurements in the region,

-describe the plan for determining the major source areas for atmospheric mercury in the Great Lakes region,

-identify common goals withother programs and potential for collaboration.

The UMAQL sponsored the workshop to promote cooperation among the Great Lakes agencies that would be needed to establish the regional monitoring network. Involving these groups in the design of the monitoring activities proved to be an important step in generating support for the project.

Monitoring Sites Established

The UMAQL has established more than ten sites for the GLAMAP monitoring network. These include the five Integrated Atmospheric Deposition Network (IADN) master sites along the Great Lakes shores. The other sampling locations were chosen by the workshop participants to complete the spatial coverage of the Great Lakes region. Selected sites were required to be in rural or remote areas in order to investigate the regional transport of atmospheric mercury. The locations of the GLAMAP sites within the Great Lakes region are displayed in Figure 1.

Figure 1. Atmospheric Mercury Network Site Locations

Site Installations

UMAQL staff began installation of the sampling equipment and operator training for GLAMAP in November 1994. The sampling equipment includes a fiberglass box mounted to the top of a three meter pole. Inlets to the sample filter packs protrude from the bottom of the box during sampling. Hard-walled polyethylene tubing connects the sampling box to the pump unit, which consists of three separate pumps and an internal heater. The unit is enclosed in an insulated wooden box for protection during harsh winter conditions encountered at several of the sites.
After the equipment was installed and tested, site operators were trained in the proper techniques for handling and collecting atmospheric mercury samples. Many of the operators had collected samples for other research projects and already had experience with standard operating procedures for air pollution studies.

Point Petre, Ontario

Atmospheric mercury monitoring was established at this Canadian IADN site in November 1994 with the support of AES/CARE. Darrel Smith collects the samples at this site on the northeast shore of Lake Ontario near Picton, Ontario.

Point Petre, Ontario

Burnt Island, Ontario

This Canadian IADN site began atmospheric mercury sampling in early December 1994 with the support of AES/CARE. Mark and Nancy Witty operate the monitoring equipment located near Gore Bay on the southwestern end of Manitoulin Island in northern Lake Huron.

Sleeping Bear Dunes, Michigan

Atmospheric mercury sampling began at this US IADN site in June 1994 as part of the Lake Michigan Mass Balance Study with the support of EPA-GLNPO. This site was also included in the GLAMAP network and operations are currently supported by EPA-NERL. Beth LaValley collects the samples within this national lakeshore

Eagle Harbor, Michigan

Atmospheric mercury monitoring was added to this US IADN site in February 1995 with the support of EPA-GLNPO. Shuli and Dennis Sotala perform the ambient mercury sampling at this site near the tip of the Keweenaw peninsula on Lake Superior.

Sturgeon Point, New York

In early February 1995, atmospheric mercury sampling began at this US IADN site with the support of EPA-GLNPO and EPA-NERL. Kelly Monahan collects the samples with help from Mary Rossi. The site is located on the eastern shore of Lake Erie south of Buffalo near Evans Center, NY.

Bondville, Illinois

Sampling for atmospheric mercury was established at this site for the Lake Michigan Mass Balance Study in July 1994 with the support of EPA-GLNPO. The site was included in the GLAMAP network and operations are currently supported through EPA-NERL. Mike Snider performs the mercury sampling at this inland site to the southwest of southern Lake Michigan near Champaign, IL.

Wildcat Mountain, Wisconsin

Atmospheric mercury sampling was added to this NADP site in early December 1994 and is operated by the Wisconsin DNR. Kathy Felt and Karen Teed collect the samples within this state park near Ontario, WI.

Wildcat Mountain, WI

Salt Fork Lake, Ohio

The Ohio EPA established this monitoring site in late January 1995 at the edge of the lake within the state park area northeast of Cambridge, OH. Bill Colon of the Ohio EPA operates the mercury sampling equipment and Jim Loper is the back-up operator.

Dexter, Michigan

Atmospheric mercury monitoring was re-established at this NDDN site within a University of Michigan research area in March 1995. UMAQL staff operate the sampling equipment at this site.

Cedar Creek, Minnesota

Beginning in May 1995, the Minnesota PCA has supported atmospheric mercury sampling at this site. David Bosanko, manager of the Cedar Creek Natural History Area, collects the mercury samples at the site within this research preservation area in Bethel, MN.

Additional Sites

Other UMAQL projects using the same sampling and analysis procedures will provide additional data that will complement the GLAMAP sites (Figure 1).

Since December 1992, the UMAQL has been conducting atmospheric mercury sampling near Lake Champlain at the Proctor Maple Research Center in Underhill Center, VT. Tim Scherbatskoy of the University of Vermont and the Vermont Monitoring Cooperative supervises the mercury monitoring at this site. Joanne Cummings collects the samples with help from Mim Pendleton.

Three additional sites in the southern Lake Michigan basin were operational through October 1995 as part of the Lake Michigan Mass Balance Study. Two of the sites were located in rural areas near the lake shore: Kenosha, WI and South Haven, MI. The third site was located in downtown Chicago, IL.

Precipitation Collection

The UMAQL is also conducting event precipitation measurements for mercury and trace elements at several monitoring locations. These include Eagle Harbor, Sleeping Bear Dunes and Dexter, MI, as well as Bondville, IL and Underhill, VT. A MIC-B automatic precipitation collector with a UMAQL-designed funnel insert is employed at all of the sites.
Weekly collection of precipitation for mercury analysis is also being conducted by other research groups at Wildcat Mountain, WI and Sturgeon Point, NY using different collection methods.

Regional Database Generated

The measurements of atmospheric mercury and trace metals for the GLAMAP multi-site network will generate a significant amount of data over the two years of the study.

Analysis and interpretation of this large data base will provide the first spatially resolved assessment of atmospheric mercury levels for the entire Great Lakes region. Seasonal variation in atmospheric mercury concentrations, as well as year-to-year variation, will be evaluated based on the two years of measurements.

Air mass trajectories for each site will be used to investigate the transport of this contaminant across theregion. Hybrid receptor modeling techniques will combine the air mass trajectories with the levels of atmospheric mercury to quantify the relative impact of different source areas for the Great Lakes region.

Trace metal levels will be used in source apportionment techniques to explore the relationship between different source types and atmospheric mercury levels in the Great Lakes region.

In addition, the GLAMAP results could be used in the refinement of computer models simulating the transport and deposition of mercury in the Great Lakes region.

Preliminary Results Show Differences Within Region

The following preliminary results from the GLAMAP monitoring network are presented to illustrate the site-to-site variation in ambient mercury concentrations that will become the basis for identifying source areas for this contaminant in the Great Lakes region. Emphasis here is on vapor-phase mercury levels, since several months of data are currentlyavailable for all of the sites. These data are preliminary and requests for final results should be directed to Gerald Keeler at the UMAQL.

Vapor-phase Mercury

Concentrations for the GLAMAP monitoring locations are typical of rural/remote areas and range from 1 to 4 ng/m3. Average concentrations by site through December 1995 ranged from 1.6 ng/m3 at Cedar Creek, Minnesota to 2.0 ng/m3 at Point Petre, Ontario (Figure 2). It should be noted that for a few of the sites the average concentrations are calculated with less than 10 months of data (Cedar Creek, Dexter, Eagle Harbor).

Figure 2. Average Vapor-phase Mercury Concentrations (ng/m^3)

Sites located within the eastern and southern Great Lakes region tend to have higher average concentrations than sites in the western and northern parts of the region. When an entire year of concurrent measurements is available for all the sites it will be determined whether the average vapor-phase mercury concentrations are statistically different across the Great Lakes region.

Variability in vapor-phase mercury levels at each of the monitoring locations is more pronounced at the eastern and southern Great Lakes sites where the maximum concentrations were above 3.0 ng/m3 (Figure 3). Sites in the northern and western areas of the Great Lakes region tend to have stable vapor-phase mercuryconcentrations less than 2 ng/m3. It should be noted that the concentrations displayed in Figure 3 are for 24 hour samples collected on an every sixth day schedule.

Particle-phase Mercury

Samples analyzed to date for GLAMAP indicate particle-phase mercury concentrations range over two orders of magnitude (1 to 100 pg/m3). A similar trend is evident for particle-phase mercury, with the eastern Great Lakes sites havinghigher concentrations than the western and northern sites, although only a few months of samples have been analyzed to date. Analysis of the sample filters is currently ongoing at UMAQL. These results will be presented in a future issue of this newsletter.

Figure 3. Vapor-phase Mercury Concentrations (ng/m^3) December 1994-December 1995

Particulate Metals

Total particulate sample filters will be analyzed using x-ray fluorescence (XRF) at the US EPA-NERL. Concentrations of many elements including trace metals will be obtained from this analysis. Source signatures can be identified using these trace metal levels which may provide information on the relative contribution of different source types to atmospheric mercury levels in the Great Lakes region. Results of this analysis will also be published in a future issue of the newsletter.

Acknowledgments

Because of the regional nature of this study, cooperation from many Great Lakes federal, state and provincial agencies was needed to get the atmospheric mercury monitoring program underway. We would like to acknowledge the efforts of several people whose assistance with coordinating the funding for site operations and help with the site installations was essential:

Gary Evans, Project Manager, US EPA-NERL; Jackie Bode of the US EPA Great Lakes National Program Office (GLNPO) for the United States IADN sites; Frank Fraude and Jim Owens of the Atmospheric Environment Service/Center for Atmospheric Research Experiments (AES/CARE) in Canada for the two Canadian IADN sites; Rick Strassman of the Minnesota Pollution Control Agency; Phil Downey of the Ohio EPA; Doug Knauer, Mark Allen and Bruce Rodger of the Wisconsin DNR; Marty Auer and James Pauer at Michigan Technological University; Kim Irvine at Buffalo State College; Clyde Sweet and Donald Dolske at Illinois State Water Survey; Steve Yancho and Tom Van Zoeren at Sleeping Bear Dunes National Lakeshore.

In Closing

Atmospheric Mercury in the Great Lakes Region will be published over the next two years to disseminate the key findings of the project. This first issue focuses on progress to date including the workshop in July 1994, descriptions of the monitoring locations, and the various agencies involved. Preliminary summaries of data available to date are also presented.

Future Issues
Plans for future issues include an analysis of the spatial and seasonal variation of atmospheric mercury concentrations in the Great Lakes region using the first year of results, followed by an assessment of the regional transport and source areas for the atmospheric mercury.

Send comments or requests for copies of the newsletter to:

Gerald Keeler, Director
Univ. of Michigan Air Quality Lab.
Dept. of Environ. and Ind. Health
School of Public Health
109 S. Observatory
Ann Arbor, MI 48109-2029.
e-mail: jkeeler@umich.edu

Editor: Janet Burke

Production Coordinator:Anne Heybey