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- Oyabu, Ikumi, et al.
(författare)
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Chemical compositions of solid particles present in the Greenland NEEM ice core over the last 110,000 years
- 2015
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Ingår i: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 120:18, s. 9789-9813
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Tidskriftsartikel (refereegranskat)abstract
- This study reports the chemical composition of particles present along Greenland's North Greenland Eemian Ice Drilling (NEEM) ice core, back to 110,000years before present. Insoluble and soluble particles larger than 0.45 mu m were extracted from the ice core by ice sublimation, and their chemical composition was analyzed using scanning electron microscope and energy dispersive X-ray spectroscopy and micro-Raman spectroscopy. We show that the dominant insoluble components are silicates, whereas NaCl, Na2SO4, CaSO4, and CaCO3 represent major soluble salts. For the first time, particles of CaMg(CO3)(2) and Ca(NO3)(2)center dot 4H(2)O are identified in a Greenland ice core. The chemical speciation of salts varies with past climatic conditions. Whereas the fraction of Na salts (NaCl+Na2SO4) exceeds that of Ca salts (CaSO4+CaCO3) during the Holocene (0.6-11.7kyr B.P.), the two fractions are similar during the BOlling-AllerOd period (12.9-14.6kyr B.P.). During cold climate such as over the Younger Dryas (12.0-12.6kyr B.P.) and the Last Glacial Maximum (15.0-26.9kyr B.P.), the fraction of Ca salts exceeds that of Na salts, showing that the most abundant ion generally controls the salt budget in each period. High-resolution analyses reveal changing particle compositions: those in Holocene ice show seasonal changes, and those in LGM ice show a difference between cloudy bands and clear layers, which again can be largely explained by the availability of ionic components in the atmospheric aerosol body of air masses reaching Greenland.
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| 2. |
- Oyabu, Ikumi, et al.
(författare)
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Compositions of Dust and Sea Salts in the Dome C and Dome Fuji Ice Cores From Last Glacial Maximum to Early Holocene Based on Ice-Sublimation and Single-Particle Measurements
- 2020
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Ingår i: Journal of Geophysical Research - Atmospheres. - 2169-897X .- 2169-8996. ; 125:4
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Tidskriftsartikel (refereegranskat)abstract
- We analyzed the chemical compositions of dust and sea-salt particles in the EPICA Dome C (EDC) ice core during 26-7 kyr BP using an ice-sublimation technique and compared the results with existing data of the Dome Fuji (DF) ice core. Combined with ion concentration data, our data suggested similar sea-salt fluxes in both cores and significantly lower dust flux in the EDC core. The differences in modal size and aspect ratio of dust particles between the two cores support the dominance of Patagonian source suggested by earlier works. The compositions of calcic dust showed major change at similar to 17 kyr BP, possibly reflecting a relative increase in dust transported via the upper troposphere. The calcium sulfate fraction was higher in the DF core than in the EDC core after similar to 17 kyr BP, suggesting that higher Patagonian dust contribution to the DF region. Abundant NaCl particles were found in the DF core in comparison with the EDC core from the LGM to early Holocene, possibly because of the high concentration of terrestrial dust in the DF core that reduced acid availability for sea-salt modification. During the Holocene, the lower NaCl fraction and Cl-/Na+ ratio in the EDC core suggested that most Cl- was lost to the atmosphere from snow at Dome C, while it was preserved at Dome Fuji as NaCl and solid solution.
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