TY - JOUR
T1 - Stabilization of natural organic matter by short-range-order Iron hydroxides
AU - Chen, Kai Yue
AU - Chen, Tsan Yao
AU - Chan, Ya Ting
AU - Cheng, Ching Yun
AU - Tzou, Yu Min
AU - Liu, Yu Ting
AU - Teah, Heng Yi
N1 - Funding Information:
We are grateful to Dr. Jyh-Fu Li for assistance at beamline 17C and Dr. Jin-Ming Chen for assistance at beamline 20A, NSRRC. This work is financially supported by the Ministry of Science and Technology, ROC, under Project Nos. 101-2313-B-005-047-MY3, 102-2313-B-029-005-MY2, 103-2112-M-007-022-MY3, and 104-2311-B-005-016-MY3.
Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/12/6
Y1 - 2016/12/6
N2 - 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.
AB - 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.
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U2 - 10.1021/acs.est.6b02793
DO - 10.1021/acs.est.6b02793
M3 - Article
C2 - 27782386
AN - SCOPUS:85021853260
SN - 0013-936X
VL - 50
SP - 12612
EP - 12620
JO - Environmental Science and Technology
JF - Environmental Science and Technology
IS - 23
ER -