| 2. |
- Alastuey, Andres, et al.
(författare)
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Geochemistry of PM10 over Europe during the EMEP intensive measurement periods in summer 2012 and winter 2013
- 2016
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 16:10, s. 6107-6129
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Tidskriftsartikel (refereegranskat)abstract
- The third intensive measurement period (IMP) organised by the European Monitoring and Evaluation Programme (EMEP) under the UNECE CLTRAP took place in summer 2012 and winter 2013, with PM10 filter samples concurrently collected at 20 (16 EMEP) regional background sites across Europe for subsequent analysis of their mineral dust content. All samples were analysed by the same or a comparable methodology. Higher PM10 mineral dust loadings were observed at most sites in summer (0.5-10aEuro-A mu gaEuro-m(-3)) compared to winter (0.2-2aEuro-A mu gaEuro-m(-3)), with the most elevated concentrations in the southern- and easternmost countries, accounting for 20-40aEuro-% of PM10. Saharan dust outbreaks were responsible for the high summer dust loadings at western and central European sites, whereas regional or local sources explained the elevated concentrations observed at eastern sites. The eastern Mediterranean sites experienced elevated levels due to African dust outbreaks during both summer and winter. The mineral dust composition varied more in winter than in summer, with a higher relative contribution of anthropogenic dust during the former period. A relatively high contribution of K from non-mineral and non-sea-salt sources, such as biomass burning, was evident in winter at some of the central and eastern European sites. The spatial distribution of some components and metals reveals the influence of specific anthropogenic sources on a regional scale: shipping emissions (V, Ni, and SO42-) in the Mediterranean region, metallurgy (Cr, Ni, and Mn) in central and eastern Europe, high temperature processes (As, Pb, and SO42-) in eastern countries, and traffic (Cu) at sites affected by emissions from nearby cities.
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| 3. |
- Fisher, Rebecca E., et al.
(författare)
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Measurement of the C-13 isotopic signature of methane emissions from northern European wetlands
- 2017
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Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 31:3, s. 605-623
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Tidskriftsartikel (refereegranskat)abstract
- Isotopic data provide powerful constraints on regional and global methane emissions and their source profiles. However, inverse modeling of spatially resolved methane flux is currently constrained by a lack of information on the variability of source isotopic signatures. In this study, isotopic signatures of emissions in the Fennoscandian Arctic have been determined in chambers over wetland, in the air 0.3 to 3m above the wetland surface and by aircraft sampling from 100m above wetlands up to the stratosphere. Overall, the methane flux to atmosphere has a coherent delta C-13 isotopic signature of -71 +/- 1%, measured in situ on the ground in wetlands. This is in close agreement with delta C-13 isotopic signatures of local and regional methane increments measured by aircraft campaigns flying through air masses containing elevated methane mole fractions. In contrast, results from wetlands in Canadian boreal forest farther south gave isotopic signatures of -67 +/- 1%. Wetland emissions dominate the local methane source measured over the European Arctic in summer. Chamber measurements demonstrate a highly variable methane flux and isotopic signature, but the results from air sampling within wetland areas show that emissions mix rapidly immediately above the wetland surface and methane emissions reaching the wider atmosphere do indeed have strongly coherent C isotope signatures. The study suggests that for boreal wetlands (>60 degrees N) global and regional modeling can use an isotopic signature of -71 parts per thousand to apportion sources more accurately, but there is much need for further measurements over other wetlands regions to verify this.
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