USGS Mercury Research Laboratory
USGS Mobile Atmospheric Mercury Lab
Mercury (Hg) in the atmosphere is derived from both natural and man-related sources, although there is good scientific concurrence that currently that man’s emissions are about twice that of natural. Once in the atmosphere, mercury from various sources mixes rapidly and has a relatively long half life (about six months), and as such at any location atmospheric mercury contributions are derived from global inventories. Discerning the relative importance of local vs regional vs global source contributions remains a challenging scientific endeavor requiring sophisticated instrumentation capable of quantifying specific forms of mercury at ambient levels, and relevant air chemistry indicators that are helpful for diagnosing sources and chemical conditions that promote important reactions. In response to this scientific need, the Mercury Research Team invested assembled the Mobile Atmospheric Lab (insert link to FS 2007-3071) in 2003 deployed it to southern Colorado and Yellowstone National Park. Since then, the Lab has been deployed to locations spanning most of the continental United States and yielded many scientific reports. The Lab is designed to improve our understanding of mercury chemistry in the atmosphere and provide wet and dry deposition estimates for mercury to supplement our other mercury research projects. The mobility of the MAML allows us to investigate the mechanisms behind regional differences in Hg deposition and the interactions of mercury with changes in the sources of air masses.
What can the Mobile Atmospheric Lab do?
Mercury in the atmosphere is operationally defined into three categories: gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and fine particulate-matter bound mercury (Hg-PM). GEM is the most common form of mercury in the atmosphere. GEM has relatively long residence time (about six months) and is transported globally. RGM is an ionic form (Hg2+) that is bound to other elements (Cl-, NO3, Br-) and has intermediate travel lengths residence times in the atmosphere. Hg-PM is mercury that is attached to aerosols (fine particulate matter, or PM), and has relatively short travel distances and residence times. The oxidized forms of mercury (RGM and Hg-PM) are ofen called “reactive mercury species” and are present in much smaller quantities (approximately 2 – 4% of the mercury in the atmosphere). In addition, they are generally derived from local-to-regional scale sources, although formation of RGM at altitude is commonly seen.
The USGS Mobile Atmospheric Lab is equipped with a Tekran™ air mercury speciation system (Models 2537A, 1130, and 1135) for measuring the three species of mercury. To supplement the Hg data collected on board are analyzers for ozone, nitric oxides, sulfur dioxide, carbon monoxide, and particulate mass (PM2.5). The mobile lab also has a full suite of meteorological sensors and wet deposition collector that can be deployed. All instruments can be remotely monitored and data collected using wireless technology.
Where has the USGS Mobile Atmospheric Lab been?
The Mercury Research Team has traveled widely with the Mobile Atmospheric Lab across the continental United States. (See map below.) The chosen study locations represent a wide range of conditions and study purposes, including: (1) background/remote condition assessments; (2) urban and near-source condition assessments; and, (3) coastal locations where we have been examining the influence of the marine boundary layer on atmospheric mercury concentrations and speciation. Scientific results from these deployments are shown in the publication list (below), including a recent summary paper that compares data from nine sites (Engle et al., 2010).
Publications derived from deployments of the USGS Mobile Atmospheric Lab:
Engle, Mark. A., Michael T. Tate, David P. Krabbenhoft, James J. Schauer, Allan Kolker, James B. Shanley,
Engle, Mark, Tate, Michael T., Krabbenhoft, David P., Kolker, Allan, Olson, Mark L., Edgerton, Eric S., DeWild,
Hall, B. D., M. L. Olson, A. P. Rutter, R. R. Frontiera, D. P. Krabbenhoft, D. S. Gross, M. Yuen, T. M. Rudolph,
Kolker, A., Engle, M.A., Krabbenhoft, D.P., and Olson, M.L., 2007, Investigating Atmospheric Mercury with the
Kolker, A., M. L. Olson, D. P. Krabbenhoft, M. T. Engle, and M. A. Engle. 2010. Patterns of mercury dispersion from
Manolopoulos, H., Snyder, D. C., Schauer, J. J., Hill, J. S., Turner, J. R., Olson, M. L., and Krabbenhoft, D. P., 2007a,
Manolopoulos, H., Snyder, D. C., Schauer, J. J., Hill, J. S., Turner, J. R., Olson, M. L., and Krabbenhoft, D.P., 2007b,
Mobile Atmospheric Mercury Lab photos