Research Highlight:
NOAA Scientists Study Mercury at Grand Bay National Estuarine Research Reserve

On January 18, 2008 scientists from NOAA’s Air Resources Laboratory (ARL) completed final upgrades and installation of ambient air mercury monitoring equipment at a permanent site within the Grand Bay National Estuarine Research Reserve (NERR), located within the Grand Bay National Wildlife Refuge in Moss Point, Mississippi. Continuous measurements of elemental mercury (Hg0), reactive gaseous mercury (RGM), fine particulate mercury (Hg-P), carbon monoxide (CO), sulfur dioxide (SO₂), ozone (O3), and oxides of nitrogen (NO/NOY) are being made from a mobile trailer stationed at the coastline of the Gulf of Mexico. The trailer, which provides climate control for the instrumentation and data recording devices, as well as work space for instrument calibration and maintenance, can be evacuated from the site in less than an hour if severe weather approaches. In addition to the trailer, a 10-meter walk- up aluminum tower was installed to hold the instrument inlet systems and meteorological sensors. ARL scientists oversee the collection, processing, and interpretation of the incoming data. This study is being conducted in partnership with NERR staff, who conduct routine operations and coordinate collaborative research activities, and NOAA’s National Centers for Coastal Ocean Science, who provided funding for vital infrastructure support and state-of-the art monitoring equipment.

Mercury is a powerful neurological toxin. Release of mercury compounds to the atmosphere through natural (e.g. soil evasion) and anthropogenic (coal combustion, waste incineration) processes, followed by “dry” deposition and precipitation, often constitutes the dominant loading mechanism to watersheds. People are exposed to methylmercury, the most toxic form of mercury, almost entirely by eating fish and wildlife contaminated with mercury. Fish consumption in coastal areas is typically much higher than the national average, and every state along the Gulf of Mexico has widespread fish consumption advisories for mercury. Data from the National Atmospheric Deposition Program indicate that mercury concentrations in precipitation in the Gulf of Mexico region are some of the highest in the United States. However, total atmospheric loadings of mercury to this region are not well characterized.

ARL’s mercury monitoring station at the Grand Bay NERR constitutes one of the first such stations in an emerging multi-agency national mercury network. Long-term measurements provide essential information needed to better quantify atmospheric loadings to local watersheds, discern natural versus anthropogenic sources of mercury, and elucidate source-receptor relationships from known or suspected emission sources. The collected data will facilitate a more thorough evaluation of NOAA’s mercury models. These models are key to establishing clear linkages between atmospheric processes (emission, atmospheric chemistry, deposition) and aquatic and biochemical processes that govern the incorporation and migration of mercury through the food web. This research supports NOAA’s goal to “Protect, Restore, and Manage the Use of Coastal and Ocean Resources through an Ecosystem Approach to Management.”