Oxidation of elemental Hg in anthropogenic and marine airmasses

by H. Timonen, J. L. Ambrose, D. A. Jaffe
Atmospheric Chemistry and Physics ()
Get full text at journal

Abstract

Mercury (Hg) is a neurotoxin that bioaccumulates in the food chain.\nMercury is emitted to the atmosphere primarily in its elemental form,\nwhich has a long lifetime allowing global transport. It is known that\natmospheric oxidation of gaseous elemental mercury (GEM) generates\nreactive gaseous mercury (RGM) which plays an important role in the\natmospheric mercury cycle by enhancing the rate of mercury deposition to\necosystems. However, the primary GEM oxidants, and the chemical\ncomposition of RGM are poorly known. Using speciated mercury\nmeasurements conducted at the Mt. Bachelor Observatory since 2005 we\npresent two previously unidentified sources of RGM to the free\ntroposphere (FT). Firstly, we observed elevated RGM concentrations,\nlarge RGM/GEM-ratios, and anti-correlation between RGM and GEM during\nAsian long-rang transport events, demonstrating that RGM is formed from\nGEM by in-situ oxidation in some anthropogenic pollution plumes in the\nFT. During the Asian pollution events the measured RGM/GEM-enhancement\nratios reached peak values, up to similar to 0.20, which are\nsignificantly larger than ratios typically measured (RGM/GEM < 0.03) in\nthe Asian source region. Secondly, we observed very high RGM levels -\nthe highest reported in the FT - in clean air masses that were processed\nupwind of Mt. Bachelor Observatory over the Pacific Ocean. The high RGM\nconcentrations (up to 700 pgm(-3)), high RGM/GEM-ratios (up to 1), and\nvery low ozone levels during these events provide observational evidence\nindicating significant GEM oxidation in the lower FT in some conditions.

Cite this document (BETA)

Readership Statistics

10 Readers on Mendeley
by Discipline
 
50% Earth and Planetary Sciences
 
20% Chemistry
 
10% Environmental Science
by Academic Status
 
40% Researcher
 
40% Student > Ph. D. Student
 
20% Professor
by Country
 
10% India
 
10% Japan
 
10% United States

Sign up today - FREE

Mendeley saves you time finding and organizing research. Learn more

  • All your research in one place
  • Add and import papers easily
  • Access it anywhere, anytime

Start using Mendeley in seconds!

Sign up & Download

Already have an account? Sign in