Stabilization of Natural Organic Matter by Short-Range-Order Iron Hydroxides

详细信息    查看全文

• 作者：Kai-Yue Chen ; Tsan-Yao Chen ; Ya-Ting Chan ; Ching-Yun Cheng ; Yu-Min Tzou ; Yu-Ting Liu ; Heng-Yi Teah
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：December 6, 2016
• 年：2016
• 卷：50
• 期：23
• 页码：12612-12620
• 全文大小：363K
• ISSN：1520-5851

文摘

Dissolved organic matter (DOM) is capable of modifying the surfaces of soil minerals (e.g., Fe hydroxides) or even forming stable co-precipitates with Fe(III) in a neutral environment. The DOM/Fe co-precipitation may alter biogeochemical carbon cycling in soils if the relatively mobile DOM is sorbed by soil minerals against leaching, runoff, and biodegradation. In this study, we aimed to determine the structural development of DOM/Fe co-precipitates in relation to changes in pH and C/(C + Fe) ratios using XRD, XPS, Fe K-edge XAS, FTIR, and C-NEXAFS techniques. The results showed that in the system with bulk C/(C + Fe) molar ratios ≤0.65, the ferrihydrite-like Fe domains were precipitated as the core and covered by the C shells. When the C/(C + Fe) molar ratio ranged between 0.71 and 0.89, the emerging Fe–C bonding suggested a more substantial association between Fe domains including edge- and corner-sharing FeO₆ octahedra and DOM. With C/(C + Fe) bulk molar ratios ≥0.92, only corner-sharing FeO₆ octahedra along with Fe–C bonding were found. The homogeneously distributed C and Fe domains caused the enhancement of Fe and C solubilization from co-precipitates. The C/(C + Fe) ratios dominated structural compositions and stabilities of C/Fe co-precipitates and may directly affect the Fe and C cycles in soils.