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    Solid-phase phosphorus speciation in Saharan Bodélé depression dusts and source sediments

    Hudson-Edwards, Karen A. and Bristow, Charlie S. and Cibin, G. and Mason, G. and Peacock, C.L. (2014) Solid-phase phosphorus speciation in Saharan Bodélé depression dusts and source sediments. Chemical Geology 384 , pp. 16-26. ISSN 0009-2541.

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    Phosphorus (P) is one of the most important limiting nutrients for the growth of oceanic phytoplankton and terrestrial ecosystems, which in turn contributes to CO2 sequestration. The solid-phase speciation of P will influence its solubility and hence its availability to such ecosystems. This study reports on the results of X-ray diffraction, electron microprobe chemical analysis and X-ray mapping, chemical extractions and X-ray absorption near-edge spectroscopy analysis carried out to determine the solid-phase speciation of P in dusts and their source sediments from the Saharan Bodélé Depression, the world’s largest single source of dust. Chemical extraction data suggest that the Bodélé dusts contain 28 to 60% (mean 49%) P sorbed to, or co-precipitated with Fe (hydr)oxides, < 10% organic P, 21-50% (mean 32%) detrital apatite P, and 10-22% (mean 15%) authigenic-biogenic apatite P. This is confirmed by the other analyses, which also suggest that the authigenic-biogenic apatite P is likely fish bone and scale, and that this might form a larger proportion of the apatite pool (33 +/− 22%) than given by the extraction data. This is the first-ever report of fish material in aeolian dust, and it is significant because P derived from fish bone and scale is relatively soluble and is often used as a soil fertilizer. Therefore, the fish-P will likely be the most readily form of Bodélé P consumed during soil weathering and atmospheric processing, but given time and acid dissolution, the detrital apatite, Fe-P and organic-P will also be made available. The Bodélé dust input of P to global ecosystems will only have a limited life, however, because its major source materials, diatomite in the Bodélé Depression, undergo persistent deflation and have a finite thickness.


    Item Type: Article
    Keyword(s) / Subject(s): Bodélé Depression, Sahara, dust, phosphorus, fish, apatite, P-sorbed Fe (hydr)oxide
    School: School of Science > Earth and Planetary Sciences
    Depositing User: Administrator
    Date Deposited: 30 Jun 2014 11:26
    Last Modified: 11 Jun 2021 22:44


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