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- Abrahamsson, Katarina, 1957, et al.
(författare)
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Organic bromine compounds produced in sea ice in Antarctic winter
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- During polar springtime, active bromine drives ozone, a greenhouse gas, to near-zero levels. Bromine production and emission in the polar regions have so far been assumed to require sunlight. Here, we report measurements of bromocarbons in sea ice, snow, and air during the Antarctic winter that reveal an unexpected new source of organic bromine to the atmosphere during periods of no sunlight. The results show that Antarctic winter sea ice provides 10 times more bromocarbons to the atmosphere than Southern Ocean waters, and substantially more than summer sea ice. The inclusion of these measurements in a global climate model indicates that the emitted bromocarbons will disperse throughout the troposphere in the southern hemisphere and through photochemical degradation to bromine atoms, contribute similar to 10% to the tropospheric reactive bromine budget. Combined together, our results suggest that winter sea ice could potentially be an important source of atmospheric bromine with implications for atmospheric chemistry and climate at a hemispheric scale.
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| 2. |
- Abbatt, J. P. D., et al.
(författare)
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Halogen activation via interactions with environmental ice and snow in the polar lower troposphere and other regions
- 2012
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 12:14, s. 6237-6271
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Tidskriftsartikel (refereegranskat)abstract
- The role of ice in the formation of chemically active halogens in the environment requires a full understanding because of its role in atmospheric chemistry, including controlling the regional atmospheric oxidizing capacity in specific situations. In particular, ice and snow are important for facilitating multiphase oxidative chemistry and as media upon which marine algae live. This paper reviews the nature of environmental ice substrates that participate in halogen chemistry, describes the reactions that occur on such substrates, presents the field evidence for ice-mediated halogen activation, summarizes our best understanding of ice-halogen activation mechanisms, and describes the current state of modeling these processes at different scales. Given the rapid pace of developments in the field, this paper largely addresses advances made in the past five years, with emphasis given to the polar boundary layer. The integrative nature of this field is highlighted in the presentation of work from the molecular to the regional scale, with a focus on understanding fundamental processes. This is essential for developing realistic parameterizations and descriptions of these processes for inclusion in larger scale models that are used to determine their regional and global impacts.
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| 7. |
- Hammarsten, Peter, et al.
(författare)
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Immunoreactivity for prostate specific antigen and Ki67 differentiates subgroups of prostate cancer related to outcome
- 2019
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Ingår i: Modern Pathology. - : Elsevier BV. - 0893-3952 .- 1530-0285. ; 32, s. 1310-1319
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Tidskriftsartikel (refereegranskat)abstract
- Based on gene-expression profiles, prostate tumors can be subdivided into subtypes with different aggressiveness and response to treatment. We investigated if similar clinically relevant subgroups can be identified simply by the combination of two immunohistochemistry markers: one for tumor cell differentiation (prostate specific antigen, PSA) and one for proliferation (Ki67). This was analyzed in men with prostate cancer diagnosed at transurethral resection of the prostate 1975–1991 (n = 331) where the majority was managed by watchful waiting. Ki67 and PSA immunoreactivity was related to outcome and to tumor characteristics previously associated with prognosis. Increased Ki67 and decreased PSA were associated with poor outcome, and they provided independent prognostic information from Gleason score. A combinatory score for PSA and Ki67 immunoreactivity was produced using the median PSA and Ki67 levels as cut-off (for Ki67 the upper quartile was also evaluated) for differentiation into subgroups. Patients with PSA low/Ki67 high tumors showed higher Gleason score, more advanced tumor stage, and higher risk of prostate cancer death compared to other patients. Their tumor epithelial cells were often ERG positive and expressed higher levels of ErbB2, phosphorylated epidermal growth factor receptor (pEGF-R) and protein kinase B (pAkt), and their tumor stroma showed a reactive response with type 2 macrophage infiltration, high density of blood vessels and hyaluronic acid, and with reduced levels of caveolin-1, androgen receptors, and mast cells. In contrast, men with PSA high/Ki67 low tumors were characterized by low Gleason score, and the most favorable outcome amongst PSA/Ki67-defined subgroups. Men with PSA low/Ki67 low tumors showed clinical and tumor characteristics intermediate of the two groups above. A combinatory PSA/Ki67 immunoreactivity score identifies subgroups of prostate cancers with different epithelial and stroma phenotypes and highly different outcome but the clinical usefulness of this approach needs to be validated in other cohorts. © 2019, The Author(s).
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| 9. |
- Nerentorp, Michelle, 1986, et al.
(författare)
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Antarctic winter mercury and ozone depletion events over sea ice
- 2016
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 129, s. 125-132
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Tidskriftsartikel (refereegranskat)abstract
- During atmospheric mercury and ozone depletion events in the springtime in polar regions gaseous elemental mercury and ozone undergo rapid declines. Mercury is quicldy transformed into oxidation products, which are subsequently removed by deposition. Here we show that such events also occur during Antarctic winter over sea ice areas, leading to additional deposition of mercury. Over four months in the Weddell Sea we measured gaseous elemental, oxidized, and particulate-bound mercury, as well as ozone in the troposphere and total and elemental mercury concentrations in snow, demonstrating a series of depletion and deposition events between July and September. The winter depletions in July were characterized by stronger correlations between mercury and ozone and larger formation of particulate-bound mercury in air compared to later spring events. It appears that light at large solar zenith angles is sufficient to initiate the photolytic formation of halogen radicals. We also propose a dark mechanism that could explain observed events in air masses coming from dark regions. Br-2 that could be the main actor in dark conditions was possibly formed in high concentrations in the marine boundary layer in the dark. These high concentrations may also have caused the formation of high concentrations of CHBr3 and CH2I2 in the top layers of the Antarctic sea ice observed during winter. These new findings show that the extent of depletion events is larger than previously believed and that winter depletions result in additional deposition of mercury that could be transferred to marine and terrestrial ecosystems.
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