Airborne Vertical Profiling of Mercury Speciation near Tullahoma, TN, USA

Atmosphere

Steve Brooks²  Xinrong Ren²  Mark Cohen²  Winston T. Luke²  Paul Kelley²  Richard Artz²  Anthony Hynes³  William Landing¹ 

[1] Department of Earth, Ocean, and Atmospheric Science, Florida State University, 117 North Woodward Avenue, Tallahassee, FL 32306, USA; E-Mail:;Air Resources Laboratory, National Oceanic and Atmospheric Administration, 5830 University Research Court, College Park, MD 20740, USA; E-Mails:;Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA; E-Mail:

关键词: atmospheric mercury;    gaseous elemental mercury;    gaseous oxidized mercury;    particulate-bound mercury;    airborne measurements;    vertical profile;    HYSPLIT;   

DOI  :  10.3390/atmos5030557

来源: mdpi

【 摘 要 】

Atmospheric transport and in situ oxidation are important factors influencing mercury concentrations at the surface and wet and dry deposition rates. Contributions of both natural and anthropogenic processes can significantly impact burdens of mercury on local, regional and global scales. To address these key issues in atmospheric mercury research, airborne measurements of mercury speciation and ancillary parameters were conducted over a region near Tullahoma, Tennessee, USA, from August 2012 to June 2013. Here, for the first time, we present vertical profiles of Hg speciation from aircraft for an annual cycle over the same location. These airborne measurements included gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particulate bound mercury (PBM), as well as ozone (O₃), sulfur dioxide (SO₂), condensation nuclei (CN) and meteorological parameters. The flights, each lasting ~3 h, were conducted typically one week out of each month to characterize seasonality in mercury concentrations. Data obtained from 0 to 6 km altitudes show that GEM exhibited a relatively constant vertical profile for all seasons with an average concentration of 1.38 ± 0.17 ng∙m⁻³. A pronounced seasonality of GOM was observed, with the highest GOM concentrations up to 120 pg∙m⁻³ in the summer flights and lowest (0–20 pg∙m⁻³) in the winter flights. Vertical profiles of GOM show the maximum levels at altitudes between 2 and 4 km. Limited PBM measurements exhibit similar levels to GOM at all altitudes. HYSPLIT back trajectories showed that the trajectories for elevated GOM (>70 pg∙m⁻³) or PBM concentrations (>30 pg∙m⁻³) were largely associated with air masses coming from west/northwest, while events with low GOM (<20 pg∙m⁻³) or PBM concentrations (<5 pg∙m⁻³) were generally associated with winds from a wider range of wind directions. This is the first set of speciated mercury vertical profiles collected in a single location over the course of a year. Even though there are current concerns that the KCl denuders used in this study may under-collect GOM, especially in the presence of elevated ozone, the collected data in this region shows the strong seasonality of oxidized mercury concentrations throughout the low to middle free troposphere.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.