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Title: Formation and redox reactivity of ferrihydrite-organic carbon-calcium co-precipitates

Abstract

Complexation with minerals plays a critical role in regulating the stability of organic matter. The presence of cations is assumed to be important for the complexation between organic matter and minerals, but there is still limited direct analysis for the formation and reactivity of mineral-organic matter-cation ternary complexes, as well as governing factors for the fate of minerals and organic matter in the complexes. In order to close this knowledge gap, we investigated the formation and reactivity of ferrihydrite (Fh)-organic carbon (OC)-calcium (Ca) ternary co-precipitates. We performed microbial anaerobic Fe reduction using Shewanella putrefaciens CN32 on synthesized Fh-OC-Ca co-precipitates and characterized OC and Fe minerals using various spectroscopic and wet chemistry techniques. We discovered that Ca incorporated into the co-precipitate was a function of OC/iron (Fe) ratio, but OC incorporation was not impacted by the Ca content. During the reduction, the presence of Ca favored the formation of green rust but decreased the formation of magnetite and siderite in co-precipitates with high OC content. The reduction of Fe and reductive release of Fe-bound OC were controlled primarily by the C/Fe ratio, rather than Ca/Fe ratio. Phenolic OC was preferentially released or degraded during the reduction compared to aromatic and carboxylicmore » OC. Collectively, C/Ca incorporation data, Fe K-edge extended X-ray absorption fine structure (EXAFS) analysis for co-precipitates before and after reduction, and the reductive release of Ca and OC suggest the formation of Fh-OC-Ca ternary co-precipitates, likely with OC as bridges. The reduction of Fe and reductive release of OC were primarily controlled by the C/Fe ratio, whereas the presence of Ca affected the mineral phase transformation for Fh during the reduction of Fe. Thus, our results provide novel understanding for the formation and reactivity of Ca-based ternary co-precipitates, which can be valuable for building up process-based models for cycles of carbon and metals.« less

Authors:
 [1];  [2];  [3]; ORCiD logo [4];  [5];  [6]
  1. Univ. of Nevada, Reno, NV (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Univ. of Delaware, Newark, DE (United States)
  3. Univ. of Delaware, Newark, DE (United States); Multnomah Univ., Portland, OR (United States)
  4. Peking Univ., Beijing (China)
  5. niv. of Delaware, Newark, DE (United States)
  6. Univ. of Nevada, Reno, NV (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1527277
Report Number(s):
LLNL-JRNL-773258
Journal ID: ISSN 0016-7037; 965248
Grant/Contract Number:  
AC52-07NA27344; SC0014275; AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Geochimica et Cosmochimica Acta
Additional Journal Information:
Journal Volume: 244; Journal Issue: C; Journal ID: ISSN 0016-7037
Publisher:
The Geochemical Society; The Meteoritical Society
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; Ferrihydrite; Organic carbon; Calcium; Co-precipitates; Microbial reduction

Citation Formats

Adhikari, Dinesh, Sowers, Tyler, Stuckey, Jason W., Wang, Xilong, Sparks, Donald L., and Yang, Yu. Formation and redox reactivity of ferrihydrite-organic carbon-calcium co-precipitates. United States: N. p., 2018. Web. doi:10.1016/j.gca.2018.09.026.
Adhikari, Dinesh, Sowers, Tyler, Stuckey, Jason W., Wang, Xilong, Sparks, Donald L., & Yang, Yu. Formation and redox reactivity of ferrihydrite-organic carbon-calcium co-precipitates. United States. doi:10.1016/j.gca.2018.09.026.
Adhikari, Dinesh, Sowers, Tyler, Stuckey, Jason W., Wang, Xilong, Sparks, Donald L., and Yang, Yu. Sat . "Formation and redox reactivity of ferrihydrite-organic carbon-calcium co-precipitates". United States. doi:10.1016/j.gca.2018.09.026. https://www.osti.gov/servlets/purl/1527277.
@article{osti_1527277,
title = {Formation and redox reactivity of ferrihydrite-organic carbon-calcium co-precipitates},
author = {Adhikari, Dinesh and Sowers, Tyler and Stuckey, Jason W. and Wang, Xilong and Sparks, Donald L. and Yang, Yu},
abstractNote = {Complexation with minerals plays a critical role in regulating the stability of organic matter. The presence of cations is assumed to be important for the complexation between organic matter and minerals, but there is still limited direct analysis for the formation and reactivity of mineral-organic matter-cation ternary complexes, as well as governing factors for the fate of minerals and organic matter in the complexes. In order to close this knowledge gap, we investigated the formation and reactivity of ferrihydrite (Fh)-organic carbon (OC)-calcium (Ca) ternary co-precipitates. We performed microbial anaerobic Fe reduction using Shewanella putrefaciens CN32 on synthesized Fh-OC-Ca co-precipitates and characterized OC and Fe minerals using various spectroscopic and wet chemistry techniques. We discovered that Ca incorporated into the co-precipitate was a function of OC/iron (Fe) ratio, but OC incorporation was not impacted by the Ca content. During the reduction, the presence of Ca favored the formation of green rust but decreased the formation of magnetite and siderite in co-precipitates with high OC content. The reduction of Fe and reductive release of Fe-bound OC were controlled primarily by the C/Fe ratio, rather than Ca/Fe ratio. Phenolic OC was preferentially released or degraded during the reduction compared to aromatic and carboxylic OC. Collectively, C/Ca incorporation data, Fe K-edge extended X-ray absorption fine structure (EXAFS) analysis for co-precipitates before and after reduction, and the reductive release of Ca and OC suggest the formation of Fh-OC-Ca ternary co-precipitates, likely with OC as bridges. The reduction of Fe and reductive release of OC were primarily controlled by the C/Fe ratio, whereas the presence of Ca affected the mineral phase transformation for Fh during the reduction of Fe. Thus, our results provide novel understanding for the formation and reactivity of Ca-based ternary co-precipitates, which can be valuable for building up process-based models for cycles of carbon and metals.},
doi = {10.1016/j.gca.2018.09.026},
journal = {Geochimica et Cosmochimica Acta},
number = C,
volume = 244,
place = {United States},
year = {2018},
month = {9}
}

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