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| Titel |
Change of iron species and iron solubility in Asian dust during the long-range transport from western China to Japan |
| VerfasserIn |
Y. Takahashi, M. Higashi, T. Furukawa, S. Mitsunobu |
| 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 ; 11, no. 21 ; Nr. 11, no. 21 (2011-11-11), S.11237-11252 |
| Datensatznummer |
250010185
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| Publikation (Nr.) |
 copernicus.org/acp-11-11237-2011.pdf |
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| Zusammenfassung |
| In the North Pacific, transport and deposition of mineral dust from Asia
appear to be one of major sources of iron which can regulate growth of
phytoplankton in the ocean. In this process, it is essential to identify
chemical species of iron contained in Asian dust, because bioavailability of
iron in the ocean is strongly influenced by the solubility of iron, which in
turn is dependent on iron species in the dust. Here, we report that clay
minerals (illite and chlorite) in the dusts near the source collected at
Aksu (western China) can be transformed into ferrihydrite by atmospheric
chemical processes during their long-range transport to eastern China
(Qingdao) and Japan (Tsukuba) based on the speciation by X-ray absorption
fine structure (XAFS) and other methods such as X-ray diffraction and
chemical extraction. As a result, Fe molar ratio in Aksu
(illite : chlorite : ferrihydrite = 70 : 25 : 5)
was changed to that in Tsukuba (illite : chlorite : ferrihydrite = 65 : 10 : 25).
Moreover, leaching experiments were conducted to study the change
of iron solubility. It was found that the iron
solubility for the dust in Tsukuba (soluble iron fraction: 11.8 % and
1.10 % for synthetic rain water and seawater, respectively) was larger
than that in Aksu (4.1 % and 0.28 %, respectively), showing that iron in
the dust after the transport becomes more soluble possibly due to the
formation of ferrihydrite in the atmosphere. Our findings suggested that
secondary formation of ferrihydrite during the transport should be
considered as one of important processes in evaluating the supply of soluble
iron to seawater. |
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