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- Gårdfeldt, Katarina, 1959, et al.
(author)
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Evasion of Mercury from coastal and open waters of the Atlantic ocean and the Mediterranean sea
- 2003
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In: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 37:Suppl 1, s. S73-S84
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Journal article (peer-reviewed)abstract
- Dissolved gaseous mercury (DGM) was measured in coastal Atlantic seawater and in the Mediterranean Sea. The Atlantic measurements were performed during September 1999 at the Mace Head Atmospheric Research Station, situated on the Irish west coast. The measurements in the Mediterranean Sea were made along a 6000 km cruise path from 14 July to 9 August 2000 in the framework of the Med-Oceanor project. Total gaseous mercury (TGM) concentrations in air were continuously measured with a 5 min time resolution using an automated mercury analyser (Tekran 2537A) during both expeditions. Paired TGM and DGM samples from all campaigns showed that the surface water was supersaturated with elemental mercury. The mercury evasion was estimated using a gas exchange model (J. Geophys. Res. 97 (1992) 7373), which uses salinity, wind speed and water temperature as independent parameters. The predicted average mercury evasion from the coastal Atlantic water was 2.7 ng m−2 h−1 implying that the concentration of TGM in the Atlantic air is enhanced by mercury evasion from the sea. Measurements in different regions of the Mediterranean Sea showed spatial variations in DGM concentrations. The highest DGM concentration (90 pg l−1) was observed at a location in the Strait of Sicily (37°16N 11°52E). The mercury evasion in the eastern sector of the Mediterranean Sea (area: 32–36°N, 17–28°E) was generally higher (7.9 ng m−2 h−1) than that observed in the Tyrrhenian Sea (4.2 ng m−2 h−1) or in the western sector (2.5 ng m−2 h−1) (areas: 38–42°N, 8–13°E and 38–41°N, 7–8°E, respectively). Estimations of mercury evasion were also made at Mediterranean coastal sites using a dynamic chamber technique. In addition, a newly developed method making continuous in situ DGM measurements possible was tested.
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| 2. |
- Gårdfeldt, Katarina, 1959, et al.
(author)
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Oxidation of atomic mercury by hydroxyl radicals and photoinduced decomposition of methylmercury species in the aqueous phase
- 2001
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In: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 35:17, s. 3039-3047
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Journal article (peer-reviewed)abstract
- The rate constant for Hg0+.OH, kHg0+.OH=(2.4±0.3)×109 M−1 s−1, in the aqueous phase was determined using a relative rate technique with methyl mercury as reference compound. The .OH initiated mercury reaction proceeds via the molecular Hg(I) radical which is oxidised to Hg(II) by dissolved O2. The reaction can be of importance under certain atmospheric circumstances, such as when the aqueous phase capacity of forming OH radicals is significant and the gas phase concentration of ozone drops. The same end product, i.e. Hg(II) was observed from the photodegradation of methylmercury hydroxide. In this case, molecular Hg(I) radicals are again likely to be formed after photodegradation of the Hg–C bond with subsequent oxidation. A lifetime of 230 h of methylmercury at outdoor conditions was estimated due to this reaction. The action of .OH on methylmercury species also involves breaking of organometallic bonds and formation of Hg(II). Speciation of these reaction products from methylmercury is important for the estimation of biogeochemical cycling of mercury.
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| 3. |
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| 4. |
- Munthe, John, et al.
(author)
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Distribution of atmospheric mercury species in Northern Europe: Final results from the MOE-project
- 2003
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In: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 37:Suppl 1, s. S9-S20
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Journal article (peer-reviewed)abstract
- The mercury species over Europe (MOE) project was aimed at identifying sources, occurrence and atmospheric behaviour of atmospheric Hg species. Within MOE, emission measurements, ambient air measurements, process and regional-scale modelling and laboratory measurements were conducted. In this work, a summary of some of the main results is given. From the emission measurements, information on stack gas concentrations and emission factors for five coal fired power plants and three waste incinerators are presented. Results from field measurements of mercury species in ambient air at five locations in Northern Europe are presented. Examples from regional-scale atmospheric modelling are also given. The results emphasise the importance of information on Hg species for instance in emission inventories and measurement data from background sites. Furthermore, the importance of considering the role of the global cycling of mercury in future control strategies is emphasised
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| 5. |
- Sommar, Jonas, 1969, et al.
(author)
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A kinetic study of the gas-phase reaction between the hydroxylradical and atomic mercury
- 2001
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In: Atmos.Environ. - 1352-2310 .- 1873-2844. ; 35:17, s. 3049-3054
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Journal article (peer-reviewed)abstract
- The atom is the dominating species of mercury in the atmosphere. Its oxidation processes are of great interest since it is mainly oxidised mercury that undergoes deposition and thereby spreads into the ecosystems and becomes bioaccumulated. The kinetics of the gas-phase reaction between atomic mercury and hydroxyl radical has been determined at room temperature and atmospheric pressure of air by relative rate technique. OH radicals were produced by photolysis employing methyl nitrite. By using cyclohexane as the reference compound, the rate coefficient obtained was k(Hg0+·OH)=(8.7±2.8)×10−14 cm3 s−1 leading to natural lifetimes of mercury at global mean conditions of 4–7 month due to this reaction.
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| 6. |
- Wängberg, I, et al.
(author)
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Emissions, dispersion and human exposure of mercury from a Swedish chlor-alkali plant
- 2005
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In: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 39:39, s. 7451-7458
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Journal article (peer-reviewed)abstract
- Mercury in air near a mercury cell chlor-alkali plant in Sweden has been measured within the EU-project EMECAP. Based on the measurements and modelling the annual distributions of GEM and RGM have been calculated for the local area around the plant. The average concentration of GEM in residential areas near the plant was found to be 1-3.5 ng m(-3) higher in comparison to the background concentration in this part of Sweden. The emission of RGM (0.55 kg year(-1)) results in elevated RGM concentrations close to the plant. The greatest impact on the local area is due to wet deposition of RGM. However, only a small fraction (0.4%) of all mercury being emitted was found to be deposited in the local area. No impact on urinary mercury could be demonstrated in the population living close to the plant. (c) 2005 Elsevier Ltd. All rights reserved.
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