Active Iron Phases Regulate the Abiotic Transformation of Organic Carbon during Redox Fluctuation Cycles of Paddy Soil

Citations Over TimeTop 10% of 2021 papers

Abstract

Iron (Fe) phases are tightly linked to the preservation rather than the loss of organic carbon (OC) in soil; however, during redox fluctuations, OC may be lost due to Fe phase-mediated abiotic processes. This study examined the role of Fe phases in driving hydroxyl radical (•OH) formation and OC transformation during redox cycles in paddy soils. Chemical probes, sequential extraction, and Mössbauer analyses showed that the active Fe species, such as exchangeable and surface-bound Fe and Fe in low-crystalline minerals (e.g., green rust-like Fe phases), predominantly regulated •OH formation during redox cycles. The •OH oxidation strongly induced the oxidative transformation of OC, which accounted for 15.1-30.8% of CO₂ production during oxygenation. Microbial processes contributed 7.3-12.1% of CO₂ production, as estimated by chemical quenching and γ-irradiation experiments. After five redox cycles, 30.1-71.9% of the OC associated with active Fe species was released, whereas 5.2-7.1% was stabilized by high-crystalline Fe phases due to the irreversible transformation of these active Fe species during redox cycles. Collectively, our findings might unveil the under-appreciated role of active Fe phases in driving more loss than conservation of OC in soil redox fluctuation events.

Related Papers

• → Electrochemical and spectroelectrochemical properties of thiadiazole substituted metallo-phthalocyanines(2015)31 cited
• → Redox Materials(2007)34 cited
• → Procedure for the determination of redox potentials of chemically (and electrochemically) irreversible inorganic redox couples from spectroscopic data(1999)10 cited
• → Substituted Hydrocarbons(1972)4 cited
• Studies on the Seasonal Incidence of the Whitefly (Dialeuropora decempuncta Quaintance and Baker) Causing Leaf Curl on Mulberry in Relation to Abiotic Factors(2000)