Biosciences Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439-4843, USA.
Environ Sci Technol. 2010 Jan 1;44(1):236-42. doi: 10.1021/es902191s.
Elucidation of complex biogeochemical processes and their effects on speciation of U in the subsurface is critical for developing remediation strategies with an understanding of stability. We have developed static microcosms that are similar to bioreduction process studies in situ under laminar flow conditions or in sediment pores. Uranium L(3)-edge X-ray absorption near-edge spectroscopy analysis with depth in the microcosms indicated that transformation of U(VI) to U(IV) occurred by at least two distinct processes. Extended X-ray absorption fine structure (EXAFS) analysis indicated that initial U(VI) species associated with C- and P-containing ligands were transformed to U(IV) in the form of uraninite and U associated with Fe-bound ligands. Microbial community analysis identified putative Fe(III) and sulfate reducers at two different depths in the microcosms. The slow reduction of U(VI) to U(IV) may contribute the stability of U(IV) within microcosms at 11 months after a decrease in bioreducing conditions due to limited electron donors.
阐明复杂的生物地球化学过程及其对地下水中 U 形态的影响，对于制定了解稳定性的修复策略至关重要。我们开发了静态微宇宙，这些微宇宙类似于层流条件下或沉积物孔隙中的原位生物还原过程研究。微宇宙中铀 L(3)边 X 射线吸收近边光谱分析表明，U(VI)向 U(IV)的转化至少通过两种不同的过程发生。扩展 X 射线吸收精细结构（EXAFS）分析表明，最初与 C 和 P 含量配体结合的 U(VI)物种被转化为形式为晶质铀矿和与 Fe 结合的配体结合的 U(IV)。微生物群落分析在微宇宙的两个不同深度处鉴定出了可能的 Fe(III)和硫酸盐还原菌。由于电子供体有限，生物还原条件降低后 11 个月内微宇宙中 U(IV)的稳定性可能归因于 U(VI)的缓慢还原。
