Atmospheric Mercury Speciation:  Concentrations and Behavior of Reactive Gaseous Mercury in Ambient Air

Abstract

Knowledge of atmospheric mercury speciation is critical to understanding its fate once released from point sources. The water-soluble compounds of Hg that exist in flue gases (termed reactive gaseous mercury, RGM) are subject to far greater local removal rates than is elemental Hg vapor, but few ambient air data exist. We developed a method using refluxing mist chambers to quantify the airborne concentrations of RGM in more than 250 ∼1-h samples under ambient conditions and summarize here the results of several RGM sampling campaigns in Tennessee and Indiana from 1992 to 1995. Measured levels of RGM were generally on the order of 50−200 pg/m3, representing about 3% of total gaseous mercury (TGM) and generally exceeding regional particulate Hg concentra tions. RGM exhibits significant correlations (p < 0.05) with temperature, solar radiation, O3, SO2, and TGM, suggesting seasonal trends similar to those of other regional air pollutants. The concentrations of RGM show reproducible diel trends, peaking during midday and decreasing sharply at night. A sharp spike in RGM was measured during a local plume impaction event in Tennessee. Concentration gradients over vegetation suggested a strong ground-level sink for RGM, and RGM concentrations decreased sharply during rain events, as expected for a water-soluble gas. The levels of RGM measured here support the hypothesis that Hg dry and wet deposition may be strongly influenced by the behavior of RGM and that elevated ecosystem exposure may be possible near major point sources of RGM compounds.

Dynamic processes of mercury over the Mediterranean region: results from the Mediterranean Atmospheric Mercury Cycle System (MAMCS) project

“…Recently, a number of flux chamber experiments, especially on water surfaces have been performed to test the validity of this assumption and to determine whether it is possible to parameterise net fluxes as a function of air and sea temperature and solar irradiation (see papers in Pirrone et al, 2001a;Ferrara et al, 2000). RGM however is known to deposit rapidly (Lindberg and Stratton, 1998), although it had been assumed that RGM was primarily the result of emissions and therefore to be found relatively close to emission sources. The first results from the MAMCS campaign sites showed that RGM concentrations in the Mediterranean (far from sources, and particularly with onshore winds) were comparable to if not greater than RGM concentrations in much more industrial northern Europe.…”

“…Divalent gas mercury is known to deposit rapidly (Lindberg and Stratton, 1998) since it has a high deposition velocity. In agreement with the literature (Schroeder and Munthe, 1998) the highest amounts of Hg II are dry-deposited near the sources (Figs.…”

Influences on and patterns in total gaseous mercury (TGM) at Harwell, England

“…GEM is the predominant form, making up >95% of total atmospheric mercury 12,13 . In this form mercury is mostly unreactive, with low wet and dry deposition rates 14 , making this the leading vector by which mercury is transported in the global mercury cycle.…”

Catalytic Reduction of Oxidized Mercury to Elemental Form by Transition Metals for Hg CEMS

“…수은은 잔류독성이 크고 장기간에 걸쳐 인간과 동식물에 악영향을 주는 대표적인 중금속 오염물질의 하나이다 [1][2][3]. 수 은은 인체 및 생태계에 직․간접적인 영향을 미치는 신경독성 물질로서 생물의 성장장애 및 생물농축을 일으킨다.…”