Biogeochemical reactions and release of iron-bound organic carbon during the redox processes. Final report
- Univ. of Nevada, Reno, NV (United States)
Accurate simulation and prediction for reactions of soil organic carbon (OC) under different biogeochemical conditions remain a grand challenge. This project aims to investigate the transformation and degradation of OC under anaerobic and aerobic conditions as well as anaerobic-aerobic transitions, as well as its coupling with reactions for iron (Fe) oxide minerals. We determined that OC can serve as electron shuttle (including pyrogenic OC) and donor for accelerating the reduction of Fe oxide. The presence of OC can inhibit the transformation of poor crystalline Fe oxide (ferrihydrite) to other more crystalline forms. Reduction of Fe oxide can lead to the mobilization of OC, depending on the ratio of OC/Fe. More condensed aromatic OC can be selectively associated with Fe oxide and also resistant to the reduction release, enhancing their stability during the anaerobic reactions. Under aerobic condition, the association with Fe oxide can inhibit the degradation of OC and also its priming effects on the degradation of indigenous soil OC. During an anaerobic-aerobic transition, OC mineralization was inhibited substantially compared to controls incubated only aerobically. Our field measurement in the Arctic region revealed the importance of deep soil temperature in regulating the generation of CO2 and CH4. These results highlighted the importance of redox reactions in controlling the fate and stability of soil OC. For future studies, investigations are required to fill in the knowledge gap regarding the structure and chemical nature of important organic ligands for Fe, accurate quantification of Fe-bound OC in soils, the long-term effects of anaerobic-aerobic transitions on the OC mineralization as well as response of microbial communities to redox transitions.
- Research Organization:
- Univ. of Nevada, Reno, NV (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER). Biological Systems Science Division
- DOE Contract Number:
- SC0014275
- OSTI ID:
- 1605652
- Report Number(s):
- DOE-SC0014275
- Country of Publication:
- United States
- Language:
- English
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