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| 2. |
- Fischer, Hubertus, et al.
(författare)
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Reconstruction of millennial changes in dust emission, transport and regional sea ice coverage using the deep EPICA ice cores from the Atlantic and Indian Ocean sector of Antarctica
- 2007
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Ingår i: Earth and Planetary Science Letters. - : Elsevier BV. - 0012-821X. ; 260, s. 340-354
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Tidskriftsartikel (refereegranskat)abstract
- Continuous sea salt and mineral dust aerosol records have been studied on the two EPICA (European Project for Ice Coring inAntarctica) deep ice cores. The joint use of these records from opposite sides of the East Antarctic plateau allows for an estimate ofchanges in dust transport and emission intensity as well as for the identification of regional differences in the sea salt aerosolsource. The mineral dust flux records at both sites show a strong coherency over the last 150 kyr related to dust emission changes inthe glacial Patagonian dust source with three times higher dust fluxes in the Atlantic compared to the Indian Ocean sector of theSouthern Ocean (SO). Using a simple conceptual transport model this indicates that transport can explain only 40% of theatmospheric dust concentration changes in Antarctica, while factor 5–10 changes occurred. Accordingly, the main cause for the strong glacial dust flux changes in Antarctica must lie in environmental changes in Patagonia. Dust emissions, hence environmentalconditions in Patagonia, were very similar during the last two glacials and interglacials, respectively, despite 2–4 °C warmertemperatures recorded in Antarctica during the penultimate interglacial than today. 2–3 times higher sea salt fluxes found in bothice cores in the glacial compared to the Holocene are difficult to reconcile with a largely unchanged transport intensity and thedistant open ocean source. The substantial glacial enhancements in sea salt aerosol fluxes can be readily explained assuming sea iceformation as the main sea salt aerosol source with a significantly larger expansion of (summer) sea ice in the Weddell Sea than inthe Indian Ocean sector. During the penultimate interglacial, our sea salt records point to a 50% reduction of winter sea icecoverage compared to the Holocene both in the Indian and Atlantic Ocean sector of the SO. However, from 20 to 80 ka beforepresent sea salt fluxes show only very subdued millennial changes despite pronounced temperature fluctuations, likely due to thelarge distance of the sea ice salt source to our drill sites.
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| 3. |
- Kaufmann, Patrik, et al.
(författare)
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Ammonium and non-sea salt sulfate in the EPICA ice cores as indicator of biological activity in the Southern Ocean
- 2010
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 29:02-jan, s. 313-323
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Tidskriftsartikel (refereegranskat)abstract
- Sulfate (SO42-) and ammonium (NH4+) flux records over the last 150,000 years from both Antarctic EPICA ice cores (European Project for Ice Coring in Antarctica) are presented. The ice core record from Dome C is influenced by the Indian sector of the Southern Ocean (SO), whereas Dronning Maud Land is facing the Atlantic sector. Generally, they reflect the past atmospheric aerosol load and, thus, potentially reveal the fingerprint of marine biogenic sources from the SO. The most important feature of both, the nssSO(4)(2-) as well as NH4+ flux records, is the absence of any significant glacial cycles, in contrary to the distinct transitions for mineral dust and sea salt aerosol over the last 150,000 years. This finding challenges the iron fertilization hypothesis on long time scales, as the significant changes in dust, e.g. from the last glacial maximum toward the Holocene have neither an impact on nssSO(4)(2-) nor on NH4+ fluxes found in interior Antarctica. The inter-site correlation of both species is weak, r(2) = 0.42 for the nssSO(4)(2-) flux and r(2) = 0.12 for the NH4+ flux respectively, emphasizing the local Source characteristics of biogenic aerosol from the SO. Millennial variability in NH4+ and nssSO(4)(2-) is within the uncertainty of our flux estimates. Correlation with mineral dust and sea ice derived sodium shows only a very weak influence of dust deposition on those insignificant changes in nssSO(4)(2-) flux for the Atlantic sector of the Southern Ocean, but also small transport changes or terrigeneous sulfate contributions may contribute to those variations at EDML.
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| 4. |
- Lupi, Angelo, et al.
(författare)
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Multi-seasonal ultrafine aerosol particle number concentration measurements at the Gruvebadet observatory, Ny-lesund, Svalbard Islands
- 2016
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Ingår i: Rendiconti lincei scienze fisiche e naturali. - : Springer Science and Business Media LLC. - 2037-4631. ; 27, s. 59-71
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Tidskriftsartikel (refereegranskat)abstract
- The object of this study was to investigate the different modal behavior of ultrafine aerosol particles collected at the Gruvebadet observatory located in Ny-lesund (Svalbard Islands, 78A degrees 55'N, 11A degrees 56'E). Aerosol particle size distribution was measured in the size range from 10 to 470 nm typically from the beginning of spring to the beginning of fall during four (non-consecutive) years (2010, 2011, 2013 and 2014). The median concentration for the whole period taken into account was 214 particles cm(-3), oscillating between the median maximum in July with a concentration of 257 particles cm(-3) and a median minimum in April with 197 particles cm(-3). The median total number concentration did not present a well-defined seasonal behavior, as shown by contrast looking at the sub/modal number concentration, where distinct trends appeared in the predominant accumulation concentration recorded during April/May and the preponderant concentration of Aitken particles during the summer months. Lastly, the short side-by-side spring 2013 campaign performed at the Zeppelin observatory with a differential mobility particle sizer was characterized by an aerosol concentration mean steady difference between the two instruments of around 14 %, thereby supporting the reliability of the device located at Gruvebadet.
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| 5. |
- Traversi, Rita, et al.
(författare)
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Sulfate spikes in the deep layers of EPICA-Dome C Ice Core: Evidence of glaciological artifacts
- 2009
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 43:23, s. 8737-8743
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Tidskriftsartikel (refereegranskat)abstract
- A detailed ionic component record was performed on EPICA Dome C ice core (East Antarctica) to a depth of 3190 m using Ion Chromatography and Fast Ion Chromatography (FIC). At depths greater than 2800 m, the sulfate profile shows intense, sharp spikes which are not expected due to the smoothing of sulfate peaks by diffusion processes. Moreover, these spikes show an "anomalous" chemical composition (e.g., unusually low acidity, high Mg2+ concentration and high Mg2+/Ca2+ ratio). These peaks and the surrounding layers also exhibit good Mg2+ vs SO42- and Cl- vs Na+ correlations through both glacial and interglacial periods. Furthermore, the high-resolution analysis of two horizontally contiguous ice sections showed that some fraction of the impurities are characterized by a heterogeneous distribution. Altogether, these results suggest the occurrence of long-term postdepositional processes involving a rearrangement of impurities via migration in the vein network, characterized by sulfuric acidity and leading to the formation of soluble particles of magnesium sulfate salts, along with ionic association of ions in the liquid films along boundaries. This evidence should be taken into consideration when inferring information on for rapid climatic and environmental changes from ice core chemical records at great depths. At Dome C, the depth threshold was found to be 2800 m.
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