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. Author manuscript; available in PMC: 2013 Jun 5.
Published in final edited form as: Environ Sci Technol. 2012 May 11;46(11):6150–6157. doi: 10.1021/es204123z

Figure 1.

Figure 1

Monomeric U(IV) extraction results from mixtures of Bio1 (BP medium) and Bio5 (WLP medium). For systems Bio1, Bio3, and Bio4, corresponding Fourier transforms of the EXAFS data are provided to illustrate the incresase in U-U shell magnitude (3.85Å) following extraction of monomeric U(IV) species. In effect, the removal of monomeric U(IV) results in an increase of the fractional contribution of uraninite to the overall U(IV) signal, leading to the observed increase in amplitude of the U-U shell characteristic of this product. Dashed lines indicate shell-by-shell fits (Bio5 – pre-extraction; Bio1 – post-extraction) and linear combination fits (Bio3 – pre-extraction; Bio3 – post-extraction; Bio1 – pre-extraction) of the EXAFS data (see also Supporting Information Figures 1 and 2). A control experiment using NaOH-treaded bio-uraninite, containing essentially 100% UO2 shows that little U(IV) is removed into solution from uraninite during the extraction process.