ARL Participates in Mercury Intensive at the Grand Bay NERR
NOAA's Air Resources Laboratory (ARL) will participate in an atmospheric mercury intensive field study at the Grand Bay National Estuarine Research Reserve (NERR) in Moss Point, Mississippi from July 29 to August 14, 2010. Partners in the intensive include scientists from the Grand Bay NERR, Georgia Institute of Technology, Florida State University, University of Miami, University of Tennessee Space Institute (UTSI), Canaan Valley Institute, Florida A&M University, Mississippi Department of Environmental Quality, and NOAA's National Centers for Coastal Ocean Science (NCCOS). For the intensive campaign, the scientists will take advantage of the existing ARL mercury facility at Grand Bay to collect additional atmospheric mercury measurements and other supplemental measurements using various novel techniques and methods, including a UTSI light aircraft.
Specifically, measurements of elemental mercury and reactive gaseous mercury fluxes will be collected using conventional micrometeorological techniques, as well as through the deployment of surrogate surfaces, event-based precipitation collectors, and experimental dew collectors (Canaan Valley Institute). Halogen species in the atmosphere will be measured via mass spectrometry (Georgia Institute of Technology), and mercury isotopes will be measured in particles and in precipitation samples (Florida State University). Grand Bay NERR, Florida A&M University, and NOAA NCCOS scientists will measure mercury concentrations in biota and in water and sediment samples at various locations within the reserve. Scientists from the University of Miami will collaborate with scientists and staff from the University of Tennessee Space Institute (UTSI) to measure elemental mercury and evaluate a new system for the measurement of total reactive gaseous mercury (RGM) and individual RGM species in air samples aloft using a UTSI light aircraft. ARL will provide support measurements of sulfur dioxide, ozone, and condensation nuclei aboard the aircraft to aid in air mass identification and evaluation, and will launch ozonesondes from the NERR site to document the chemical and physical structure of the troposphere and lower stratosphere. The Mississippi Department of Environmental Quality will continue their ongoing precipitation sampling and analysis for total mercury, methyl mercury, major ions, and heavy metals to quantify wet deposition of these species during the intensive. Finally, ARL modelers will use a newly developed version of a HYSPLIT- based atmospheric mercury model to aid in interpretation of measurement data, and the datasets generated will also be used for an extensive post hoc model evaluation.
The study is intended to address key issues in atmospheric mercury research including, the importance of atmospheric transport from the upper troposphere in influencing mercury concentrations at the surface; the role of halogen compounds in mercury transformations; the identity of individual reactive gaseous mercury species; and the relative contributions of natural and anthropogenic emissions sources at local, regional, and global scales to the deposition of mercury in and around the Grand Bay NERR.
Background: The Grand Bay NERR is the site of an existing ARL facility devoted to the long-term monitoring of mercury species in the atmosphere. The site also hosts long-term and continuous measurements of meteorological parameters, reactive nitrogen compounds, SO2, carbon monoxide, O3, and black carbon, which are ancillary data used to interpret atmospheric mercury measurements. Samples of mercury in precipitation are also collected there on a weekly basis, as part of the National Atmospheric Deposition Program's Mercury Deposition Network (MDN). Hence, the Grand Bay site was chosen as a perfect location for the team of scientists to conduct the needed additional research. Data show that the Gulf of Mexico region is plagued by persistently high total mercury in precipitation. This study will allow the scientists to better understand what is unique about the region and to address questions, such as: Are mercury concentrations high because of halogens in the marine boundary layer? Or, are mercury concentrations high because frequent and widespread convective activity and rainfall continually scrub the middle and upper troposphere of reactive gaseous mercury, which may arise from halogen chemistry in the troposphere and the stratosphere? What role is played by local and regional anthropogenic mercury sources?
Significance Human exposure to mercury is primarily from the consumption of contaminated fish and other aquatic organisms. The U.S. Environmental Protection Agency has estimated that roughly 1 out of every 6 children born in the U.S. may be exposed, in-utero, to levels of mercury at concentrations sufficient to impair neurological development and motor and cognitive skills. 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. The release of mercury compounds to the atmosphere, followed by deposition, often constitutes the dominant loading mechanism to water bodies and watersheds. Data from the MDN indicate that mercury concentrations in precipitation in the Gulf of Mexico region are some of the highest in the United States. ARL is a recognized leader in the field of atmospheric mercury measurement and modeling research and is providing critical information to the Gulf region.
For More Information, contact:Winston Luke and Mark Cohen