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Title: Coupled dynamics of iron and iron-bound organic carbon in forest soils during anaerobic reduction

Authors:
ORCiD logo; ; ; ; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1398687
Grant/Contract Number:
SC0014275
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Chemical Geology
Additional Journal Information:
Journal Volume: 464; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-08 21:17:52; Journal ID: ISSN 0009-2541
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Zhao, Qian, Adhikari, Dinesh, Huang, Rixiang, Patel, Aman, Wang, Xilong, Tang, Yuanzhi, Obrist, Daniel, Roden, Eric E., and Yang, Yu. Coupled dynamics of iron and iron-bound organic carbon in forest soils during anaerobic reduction. Netherlands: N. p., 2017. Web. doi:10.1016/j.chemgeo.2016.12.014.
Zhao, Qian, Adhikari, Dinesh, Huang, Rixiang, Patel, Aman, Wang, Xilong, Tang, Yuanzhi, Obrist, Daniel, Roden, Eric E., & Yang, Yu. Coupled dynamics of iron and iron-bound organic carbon in forest soils during anaerobic reduction. Netherlands. doi:10.1016/j.chemgeo.2016.12.014.
Zhao, Qian, Adhikari, Dinesh, Huang, Rixiang, Patel, Aman, Wang, Xilong, Tang, Yuanzhi, Obrist, Daniel, Roden, Eric E., and Yang, Yu. 2017. "Coupled dynamics of iron and iron-bound organic carbon in forest soils during anaerobic reduction". Netherlands. doi:10.1016/j.chemgeo.2016.12.014.
@article{osti_1398687,
title = {Coupled dynamics of iron and iron-bound organic carbon in forest soils during anaerobic reduction},
author = {Zhao, Qian and Adhikari, Dinesh and Huang, Rixiang and Patel, Aman and Wang, Xilong and Tang, Yuanzhi and Obrist, Daniel and Roden, Eric E. and Yang, Yu},
abstractNote = {},
doi = {10.1016/j.chemgeo.2016.12.014},
journal = {Chemical Geology},
number = C,
volume = 464,
place = {Netherlands},
year = 2017,
month = 8
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on May 30, 2018
Publisher's Accepted Manuscript

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  • Iron oxide minerals play an important role in stabilizing organic carbon (OC) and regulating the biogeochemical cycles of OC on the earth surface. To predict the fate of OC, it is essential to understand the amount, spatial variability, and characteristics of Fe-bound OC in natural soils. In this study, we investigated the concentrations and characteristics of Fe-bound OC in soils collected from 14 forests in the United States and determined the impact of ecogeographical variables and soil physicochemical properties on the association of OC and Fe minerals. On average, Fe-bound OC contributed 37.8 % of total OC (TOC) in forestmore » soils. Atomic ratios of OC : Fe ranged from 0.56 to 17.7, with values of 1–10 for most samples, and the ratios indicate the importance of both sorptive and incorporative interactions. The fraction of Fe-bound OC in TOC (fFe-OC) was not related to the concentration of reactive Fe, which suggests that the importance of association with Fe in OC accumulation was not governed by the concentration of reactive Fe. Concentrations of Fe-bound OC and fFe-OC increased with latitude and reached peak values at a site with a mean annual temperature of 6.6 °C. Attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR) and near-edge X-ray absorption fine structure (NEXAFS) analyses revealed that Fe-bound OC was less aliphatic than non-Fe-bound OC. Fe-bound OC also was more enriched in 13C compared to the non-Fe-bound OC, but C/N ratios did not differ substantially. In summary, 13C-enriched OC with less aliphatic carbon and more carboxylic carbon was associated with Fe minerals in the soils, with values of fFe-OC being controlled by both sorptive and incorporative associations between Fe and OC. Overall, this study demonstrates that Fe oxides play an important role in regulating the biogeochemical cycles of C in forest soils and uncovers the governing factors for the spatial variability and characteristics of Fe-bound OC.« less
    Cited by 1
  • Iron oxide minerals play an important role in stabilizing organic carbon (OC) and regulating the biogeochemical cycles of OC on the earth surface. To predict the fate of OC, it is essential to understand the amount, spatial variability, and characteristics of Fe-bound OC in natural soils. In this study, we investigated the concentrations and characteristics of Fe-bound OC in soils collected from 14 forests in the United States and determined the impact of ecogeographical variables and soil physicochemical properties on the association of OC and Fe minerals. On average, Fe-bound OC contributed 37.8 % of total OC (TOC) in forestmore » soils. Atomic ratios of OC : Fe ranged from 0.56 to 17.7, with values of 1–10 for most samples, and the ratios indicate the importance of both sorptive and incorporative interactions. The fraction of Fe-bound OC in TOC (fFe-OC) was not related to the concentration of reactive Fe, which suggests that the importance of association with Fe in OC accumulation was not governed by the concentration of reactive Fe. Concentrations of Fe-bound OC and fFe-OC increased with latitude and reached peak values at a site with a mean annual temperature of 6.6 °C. Attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR) and near-edge X-ray absorption fine structure (NEXAFS) analyses revealed that Fe-bound OC was less aliphatic than non-Fe-bound OC. Fe-bound OC also was more enriched in 13C compared to the non-Fe-bound OC, but C/N ratios did not differ substantially. In summary, 13C-enriched OC with less aliphatic carbon and more carboxylic carbon was associated with Fe minerals in the soils, with values of fFe-OC being controlled by both sorptive and incorporative associations between Fe and OC. Overall, this study demonstrates that Fe oxides play an important role in regulating the biogeochemical cycles of C in forest soils and uncovers the governing factors for the spatial variability and characteristics of Fe-bound OC.« less
  • Soil organic carbon (SOC) can be stabilized via association with iron (Fe) and aluminum (Al) minerals. Fe and Al can be strong predictors of SOC storage and turnover in soils with relatively high extractable metals content and moderately acidic to circumneutral pH. Here we test whether pedogenic Fe and Al influence SOC content and turnover in soils with low Fe and Al content and acidic pH. In soils from four sites spanning three soil orders, we quantified the amount of Fe and Al in operationally-defined poorly crystalline and organically-complexed phases using selective chemical dissolution applied to the soil fraction containingmore » mineral-associated carbon. We evaluated the correlations of Fe and Al concentrations, mean annual precipitation (MAP), mean annual temperature (MAT), and pH with SOC content and 14C-based turnover times. We found that poorly crystalline Fe and Al content predicted SOC turnover times (p < 0.0001) consistent with findings of previous studies, while organically-complexed Fe and Al content was a better predictor of SOC concentration (p < 0.0001). Greater site-level MAP (p < 0.0001) and colder site-level MAT (p < 0.0001) were correlated with longer SOC turnover times but were not correlated with SOC content. Our results suggest that poorly crystalline Fe and Al effectively slow the turnover of SOC in these acidic soils, even when their combined content in the soil is less than 2% by mass. However, in the strongly acidic Spodosol, organo-metal complexes tended to be less stable resulting in a more actively cycling mineral-associated SOC pool.« less
  • The authors used a combination of porewater and solid phase analysis, as well as a series of sediment incubations, to quantify organic carbon oxidation by dissimilatory Fe reduction, Mn reduction, and sulfate reduction, in sediments from the Skagerrak (located off the northeast coast of Jutland, Denmark). In the deep portion of the basin, surface Mn enrichments reached 3.5 wt %, and Mn reduction was the only important anaerobic carbon oxidation process in the upper 10 cm of the sediment. In the less Mn-rich sediments from intermediate depths in the basin, Fe reduction ranged from somewhat less, to far more importantmore » than sulfate reduction. Most of the Mn reduction in these sediments may have been coupled to the oxidation of acid volatile sulfides (AVS), rather than to dissimilatory reduction. High rates of metal oxide reduction at all sites were driven by active recycling of both Fe and Mn, encouraged by bioturbation. Recycling was so rapid that the residence time of Fe and Mn oxides, with respect to reduction, ranged from 70--250 days. These results require that, on average, an atom of Fe or Mn is oxidized and reduced between 100--300 times before ultimate burial into the sediment. The authors observed that dissolved Mn[sup 2+] was completely removed onto fully oxidized Mn oxides until the oxidation level of the oxides was reduced to about 3.8, presumably reflecting the saturation by Mn[sup 2+] of highly reactive surface adsorption sites. Fully oxidized Mn oxides in sediments, then, may act as a cap preventing Mn[sup 2+] escape. They speculate that in shallow sediments of the Skagerrak, surface Mn oxides are present in a somewhat reduced oxidation level (<3.8) allowing Mn[sup 2+] to escape, and perhaps providing the Mn[sup 2+] which enriches sediments of the deep basin. 59 refs., 12 figs., 7 tabs.« less