USGS scientists setting up mercury-aerosol sampling equipment in front of the USGS Mobile Atmospheric Mercury Laboratory at the Weeks Bay Estuarine Research Reserve, Mobile, Alabama. The laboratory has onboard instrumentation to measure aerosol concentrations and to continuously monitor mercury speciation and concentrations, air quality, automated wet deposition collection, and meteorological conditions

The tower on the back of the USGS Mobile Atmospheric Mercury Laboratory on-site at Mt. Horeb, WI. The laboratory is designed to pump in air for analysis of mercury species (elemental mercury (Hg⁰), gaseous ionic mercury (Hg^+2,+1), and particulate mercury) measurements

A view of the air intake with access doors open for the mercury speciation unit of the USGS Mobile Mercury Laboratory. The intake "strips" particulate and reactive gaseous mercury species from air, allowing gaseous elemental mercury (Hg⁰) to pass to a detector. After a two-hour accumulation period, particulate and reactive gaseous mercury (Hg^+2,+1) are thermally desorbed and passed to the detector for analysis

A view of the stacked instrumentation suite inside the USGS Mobile Atmospheric Mercury Laboratory. The top four instruments continuously monitor sulfur oxides (SO_x), oxides of nitrogen (NO, NO_x), and ozone. The lower two instruments provide continuous measurements of gaseous elemental mercury (Hg⁰), reactive gaseous mercury (Hg^+2,+1), and particulate mercury in air

The USGS Mobile Atmospheric Mercury Laboratory on-site at the Weeks Bay Estuarine Research Reserve, Mobile, AL. The laboratory has satellite-dish communication equipment, which facilities rapid data acquisition, remote communications, and data transfer

Map showing locations of atmospheric mercury monitoring stations and the relative concentration of mercury in air in Yellowstone National Park, WY