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| Titel |
Ice nucleation by fertile soil dusts: relative importance of mineral and biogenic components |
| VerfasserIn |
D. O'Sullivan, B. J. Murray, T. L. Malkin, T. F. Whale, N. S. Umo, J. D. Atkinson, H. C. Price, K. J. Baustian, J. Browse, M. E. Webb |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 4 ; Nr. 14, no. 4 (2014-02-18), S.1853-1867 |
| Datensatznummer |
250118409
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| Publikation (Nr.) |
 copernicus.org/acp-14-1853-2014.pdf |
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| Zusammenfassung |
| Agricultural dust emissions have been estimated to contribute around 20%
to the global dust burden. In contrast to dusts from arid source regions, the
ice-nucleating abilities of which have been relatively well studied, soil
dusts from fertile sources often contain a substantial fraction of organic
matter. Using an experimental methodology which is sensitive to a wide range
of ice nucleation efficiencies, we have characterised the immersion mode
ice-nucleating activities of dusts (d < 11 μm)
extracted from fertile soils collected at four locations around England. By
controlling droplet sizes, which ranged in volume from 10−12 to
10−6 L (concentration = 0.02 to 0.1 wt% dust), we have been
able to determine the ice nucleation behaviour of soil dust particles at
temperatures ranging from 267 K (−6 °C) down to the homogeneous
limit of freezing at about 237 K (−36 °C). At temperatures above
258 K (−15 °C) we find that the ice-nucleating activity of soil
dusts is diminished by heat treatment or digestion with hydrogen peroxide,
suggesting that a major fraction of the ice nuclei stems from biogenic
components in the soil. However, below 258 K, we find that the ice active
site densities tend towards those expected from the mineral components in the
soils, suggesting that the inorganic fraction of soil dusts, in particular
the K-feldspar fraction, becomes increasingly important in the initiation of
the ice phase at lower temperatures. We conclude that dusts from agricultural
activities could contribute significantly to atmospheric IN concentrations,
if such dusts exhibit similar activities to those observed in the current
laboratory study. |
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