Dynamic Production of Hydroxyl Radicals during the Flooding–Drainage Process of Paddy Soil: An In Situ Column Study

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(43), P. 16340 - 16347

Published: Oct. 19, 2023

Frequent cycles of flooding and drainage in paddy soils lead to the reductive dissolution iron (Fe) minerals reoxidation Fe(II) species, all while generating a robust consistent output reactive oxygen species (ROS). In this study, we present comprehensive assessment temporal spatial variations Fe ROS during flooding-drainage process representative soil. Our laboratory column experiments showed that decrease dissolved O2 concentration led rapid reduction below water-soil interface, aqueous was transformed into solid phases over an extended time. As result, •OH production capacity liquid reduced improved. The increased from 227-271 μmol kg-1 (within 1-11 cm depth) 500-577 499-902 after 50 day, 3 month, 1 year incubation, respectively. During drainage, dynamic triggered by consumption oxidation. ROS-trapping film situ capture revealed soil surface active zone for intense H2O2 production, limited observed deeper layers (>5 cm) due penetration. These findings provide more insights complex interplay between cycling redox transition zones fields.

Language: Английский

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Stabilization of mineral-associated organic carbon in Pleistocene permafrost

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: April 13, 2023

Ice-rich Pleistocene-age permafrost is particularly vulnerable to rapid thaw, which may quickly expose a large pool of sedimentary organic matter (OM) microbial degradation and lead emissions climate-sensitive greenhouse gases. Protective physico-chemical mechanisms may, however, restrict accessibility reduce OM decomposition; that be influenced by changing environmental conditions during sediment deposition. Here we study different fractions in Siberian deposited colder warmer periods the past 55,000 years. Among known stabilization mechanisms, occlusion aggregates minor importance, while 33-74% carbon associated with small, <6.3 µm mineral particles. Preservation mineral-associated enhanced reactive iron minerals cold dry climate, reflected low CO2 production incubation experiments. Warmer wetter stabilization, shown more decomposed up 30% higher production. This shows considering stability bioavailability important for predicting future climate-carbon feedback.

Language: Английский

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Insights into the Crystallinity-Dependent Photochemical Productions of Reactive Oxygen Species from Iron Minerals

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: 58(24), P. 10623 - 10631

Published: May 23, 2024

Iron minerals are widespread in earth's surface water and soil. Recent studies have revealed that under sunlight irradiation, iron photoactive on producing reactive oxygen species (ROS), a group of key regulating elemental cycling, microbe inactivation, pollutant degradation. In nature, exhibit varying crystallinity different hydrogeological conditions. While is known parameter determining the overall activity minerals, impact mineral photochemical ROS production remains unknown. Here, we assessed from ferrihydrites with degrees crystallinity. All examined demonstrated photoactivity resulting generation hydrogen peroxide (H2O2) hydroxyl radical (•OH). The increased decreasing ferrihydrite crystallinity-dependent •OH was primarily attributed to conduction band reduction reactions, O2 by electrons being rate-limiting process. Conversely, had negligible influence photon-to-electron conversion efficiency or Fenton-like activity. difference productions led discrepant degradation organic pollutants surfaces. Our study provides valuable insights into natural systems, emphasizing significance photochemistry sites abundant lower-crystallinity such as wetland soils.

Language: Английский

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Metal mobilization from thawing permafrost to aquatic ecosystems is driving rusting of Arctic streams

Communications Earth & Environment, Journal Year: 2024, Volume and Issue: 5(1)

Published: May 20, 2024

Abstract Climate change in the Arctic is altering watershed hydrologic processes and biogeochemistry. Here, we present an emergent threat to watersheds based on observations from 75 streams Alaska’s Brooks Range that recently turned orange, reflecting increased loading of iron toxic metals. Using remote sensing, constrain timing stream discoloration last 10 years, a period rapid warming snowfall, suggesting impairment likely due permafrost thaw. Thawing can foster chemical weathering minerals, microbial reduction soil iron, groundwater transport metals streams. Compared clear reference streams, orange have lower pH, higher turbidity, sulfate, trace metal concentrations, supporting sulfide mineral as primary mobilization process. Stream was associated with dramatic declines macroinvertebrate diversity fish abundance. These findings considerable implications for drinking water supplies subsistence fisheries rural Alaska.

Language: Английский

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Microbially Driven Iron Cycling Facilitates Organic Carbon Accrual in Decadal Biochar-Amended Soil

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: 58(28), P. 12430 - 12440

Published: July 5, 2024

Soil organic carbon (SOC) is pivotal for both agricultural activities and climate change mitigation, biochar stands as a promising tool bolstering SOC curtailing soil dioxide (CO2) emissions. However, the involvement of in dynamics underlying interactions among biochar, microbes, iron minerals, fresh matter (FOM, such plant debris) remain largely unknown, especially soils after long-term amendment. We therefore introduced FOM to with without decade-long history amendment, performed microcosm incubations, evaluated well microbial properties. Biochar amendment resulted 2-fold accrual over decade attenuated FOM-induced CO2 emissions by approximately 11% during 56-day incubation through diverse pathways. Notably, facilitated microbially driven reduction subsequent Fenton-like reactions, potentially having enhanced extracellular electron transfer use efficiency long run. Throughout cycling processes, physical protection minerals could contribute accumulation debris preservation, alongside direct adsorption occlusion particles. Furthermore, slurry experiments, sterilization ferrous stimulation controls, confirmed role microbes hydroxyl radical generation biotic sequestration biochar-amended soils. Overall, our study sheds light on intricate abiotic mechanisms governing upland

Language: Английский

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