Environmental measurements with an atmospheric mercury monitor having speciation capabilities

Schroeder, W. H.; Jackson, R. A.

doi:10.1016/0045-6535(87)90123-8

Cited by 50 publications

(22 citation statements)

References 12 publications

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“…Aerosol Hg, which generally comprises less than ---5% of total airborne Hg [Schroeder and Jackson, 1987] and exists primarily in the fine fraction [Lindqvist et al, 1984], is also dry deposited to foliage but is primarily controlled by eddy diffusion. The net result of this process may be traced using natural radionuclides such as 214pb.…”

Section: A Survey Of the Limited Literature On Airborne Hg Interactiomentioning

confidence: 99%

Atmosphere‐surface exchange of mercury in a forest: Results of modeling and gradient approaches

Lindbeŕg¹,

Meyers²,

Taylor³

et al. 1992

J. Geophys. Res.

211

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We have modified recently published dry deposition models to estimate deposition velocities (Vd) for Hg in both fine aerosol and vapor form to forest canopy surfaces. Aerosol and total vapor phase Hg concentrations in air previously measured at Walker Branch Watershed in Tennessee have been used with model results to estimate dry deposition to a deciduous forest. The concentration data confirm that airborne Hg is dominated by vapor forms at this site and exhibits concentrations moderately above continental background levels. The modeled Vd values reflect published data which suggest that dry deposition of Hg vapor is strongly controlled by surface transport processes, notably stomatal and mesophyll resistances, the latter dominating. Weekly mean Vd values ranged from 0.006 (winter) to 0.12 (summer) cm s−1. We have also measured concentration gradients of Hg vapor in air above this forest to estimate air‐surface exchange during short‐term experiments. While the model results indicate that the canopy is a sink for Hg vapor, the concentration profiles suggest that the forest soils are a source during some periods, the combined effect of which is net Hg fluxes in the upward direction. Application of a detailed canopy turbulence model yielded soil emission rates of the order of 50 ng Hg m−2 h−1, ∼10% of which is deposited in the canopy. Our modeled dry deposition estimates plus limited measurements of wet deposition in this area suggest that dry and wet deposition may be comparable in magnitude.

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Section: A Survey Of the Limited Literature On Airborne Hg Interactiomentioning

confidence: 99%

Atmosphere‐surface exchange of mercury in a forest: Results of modeling and gradient approaches

Lindbeŕg¹,

Meyers²,

Taylor³

et al. 1992

J. Geophys. Res.

211

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“…Numerous studies indicate that organometallic mercury compounds constitute only from 0.3% to 1% of TGM (Lee and Iverfeldt 1991;Lin and Pehkonen 1999;Lee et al 2003). However, the studies of ambient mercury carried out in Toronto (Canada) showed episodes when TGM contained approximately 75% Hg 0 , 5% Hg +2 and 20% CH 3 Hg + (Schroeder and Jackson 1987). Gaseous mercury Hg 0 is a stable compound, slightly soluble in water, thus its removal from the atmosphere is slow, mainly through dry deposition or chemical conversion (Lin and Pehkonen 1999).…”

Section: Introductionmentioning

confidence: 96%

Speciation of Ambient Mercury in the Upper Silesia Region, Poland

Pyta

Rosik-Dulewska

Czaplicka

2008

Water Air Soil Pollut

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The paper presents results of a preliminary study on mercury concentration in the air carried out in the period of October 2006 to April 2007 at sampling sites located in the cities of Gliwice and Zabrze in the region of Upper Silesia-Poland's largest urban and industrial agglomeration. The study comprised physical (particulate matter-gaseous phase) and chemical speciation of gaseous mercury. Mercury concentration data related with two fractions of particulate matter: PM2.5 and PM10 are reported. The performed measurements indicated that the average monthly concentrations of the total mercury were in the range of 4.1 to 9.1 ng m −3 . The highest mercury concentration was observed in winter, especially in periods of low precipitation. The investigation of ambient mercury distribution indicated that 4.6% to 9.8% of the total mercury present in the air was bound to particulate matter. It has been also observed that 77% of mercury in PM10 was bound to the respirable PM2.5 fraction. Chemical speciation analysis showed that elemental mercury presented 96.1% up to 99.3% of the total gaseous mercury concentration in the air.

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“…We feel that this problem is partially caused by a lack of studies that identify the individual Hg species contributing to the air-surface exchange process. On the basis of older atmospheric speciation data [Schroeder and Jackson, 1987], it is generally assumed that total gaseous Hg (TGM) in the environment consists exclusively of Hg ø, but some recent reports have demonstrated the existence of significance amounts of dimethylmercury (DMM) in floodplain soil air [Wallschl•t'ger et al., 1995], and the emission of volatile monomethylmercury compounds (MMM) from sewage sludge amended soils [Carpi et al, 1997]. Establishing the speciation of Hg fluxes will be of fundamental importance for understanding the entire volatilization process, because each species will be formed via its chamber outlet and inlet (corrected for the positive or negative chamber blank, if necessary), Q is the chamber flushing rate, and A is the surface area covered by the chamber.…”

Section: Introductionmentioning

confidence: 99%

Factors affecting the measurement of mercury emissions from soils with flux chambers

Wallschläger¹,

Turner²,

London³

et al. 1999

J. Geophys. Res.

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Abstract. Air-surface exchange of mercury (Hg) above an arid geothermal area was measured with three parallel flux chamber experiments. The different experimental designs were intercompared with each other, with regard to the magnitude of the measured Hg fluxes and their response to environmental changes. Qualitatively, the measured Hg fluxes agreed well throughout the diurnal cycle, and in their response to environmental events and experimental manipulations, but quantitatively, there were significant discrepancies between the individua ! flux results. On average, the three designs yielded Hg fluxes agreeing within a factor of 2, but even more pronounced differences were observed during midday high emission periods and during apparent nighttime deposition events. The chamber flushing rate appears to have a very significant impact on the measured fluxes and on the response behavior to environmental change. This study demonstrates that both experimental differences and small-scale regional variability introduce large uncertainty in the estimation of natural Hg air-surface exchange by different flux chamber techniques. Also, the impact of environmental parameters on Hg air-surface exchange was studied. Rain events led to a strong increase in the Hg emissions, even when the covered soil remained dry, suggesting that the apparent chamber footprint is larger than the actually covered area. Exclusion of sunlight led to decreases in Hg emissions. Statistical analysis revealed the strongest correlations between the measured Hg fluxes and radiation and wind speed. Weaker correlations were observed with air and soil temperature and wind direction (probably due to local Hg sources). Fluxes were also inversely correlated with relative humidity.

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Environmental measurements with an atmospheric mercury monitor having speciation capabilities

Cited by 50 publications

References 12 publications

Atmosphere‐surface exchange of mercury in a forest: Results of modeling and gradient approaches

Atmosphere‐surface exchange of mercury in a forest: Results of modeling and gradient approaches

Speciation of Ambient Mercury in the Upper Silesia Region, Poland

Factors affecting the measurement of mercury emissions from soils with flux chambers

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