The association of organic matter (OM) with minerals is recognized as the most important stabilization mechanism for soil matter. This study compared properties Fe–OM complexes formed from adsorption (reaction OM to postsynthesis ferrihydrite) versus coprecipitation (formation Fe solids in presence OM). Coprecipitates and were synthesized using dissolved (DOM) extracts a forest little layer at varying molar C/Fe ratios 0.3–25.0. Sample studied by N2 gas adsorption, XRD, FTIR, EXAFS,...

Soil organic matter (SOM) is correlated with reactive iron (Fe) in humid soils, but Fe also promotes SOM decomposition when oxygen (O2) becomes limited. Here we quantify Fe-mediated OM protection vs. by adding 13C dissolved (DOM) and 57FeII to soil slurries incubated under static or fluctuating O2. We find uniformly protects only oxic conditions, DOM are added together: de novo FeIII phases suppress mineralization 35 47%, respectively. Conversely, alone increases 8% following oxidation...

Aqueous Fe(II) is known to catalyze the abiotic transformation of ferrihydrite more stable Fe minerals. However, little about impacts coprecipitated OM on Fe(II)-catalyzed and its consequences for C dynamics. Accordingly, we investigated extent pathway Fe(II)-induced OM-ferrihydrite coprecipitates as a function C/Fe ratios aqueous concentrations, implications subsequent The resulted in linear decrease with increasing ratios. secondary mineral profiles upon reaction depend concentrations At...

It has been documented that contaminants could be degraded by hydroxyl radicals (•OH) produced upon oxygenation of Fe(II)-bearing sediments. However, the dependence contaminant degradation on sediment characteristics, particularly Fe(II) species, remains elusive. Here we assessed impact abundance species in sediments •OH during oxygenation. Three natural with different contents and were oxygenated. During 10 h 200 g/L suspension, 2 mg/L phenol was negligibly for sandbeach (Fe(II): 9.11...

There is a growing acceptance that associations with soil minerals may be the most important overarching stabilization mechanism for organic matter. However, direct investigation of organo-mineral has been hampered by lack methods can simultaneously characterize matter (OM) and minerals. In this study, STXM-NEXAFS spectroscopy at C 1s, Ca 2p, Fe Al Si 1s edges was used to investigate Ca, Fe, Al, species in clay fractions from an upland pasture hillslope. Bulk techniques including N NEXAFS,...

Abiotic Fe(II) oxidation by O2 commonly occurs in the presence of mineral sorbents and organic matter (OM) soils sediments; however, this tertiary system has rarely been studied. Therefore, we examined impacts surfaces (goethite γ-Al2O3) [Suwannee River fulvic acid (SRFA)] on rates resulting Fe(III) (oxyhydr)oxides under 21 1% pO2 at pH 6. We tracked Fe dynamics adding 57Fe(II) to 56Fe-labeled goethite γ-Al2O3 characterized solids using 57Fe Mössbauer spectroscopy. found was slower low...

Abstract Despite increasing recognition of the critical role coastal wetlands in mitigating climate change, sea‐level rise, and salinity increase, soil organic carbon (SOC) sequestration mechanisms estuarine remain poorly understood. Here, we present new results on source, decomposition, storage SOC with four vegetation types, including single Phragmites australis (P, habitat I), a mixture P. Suaeda salsa (P + S, II), S. (S, III), tidal flat (TF, IV) across gradient. Values δ 13 C increased...

Ferrous iron (FeII) oxidation is an important pathway for generating reactive FeIII phases in soils, which can affect organic carbon (OC) persistence/decomposition. We explored how pO2 concentration influences FeII rates and mineral composition, this impacts the subsequent reduction anaerobic OC mineralization following a transition from oxic to anoxic conditions. conducted batch soil slurry experiments within humid tropical forest amended with isotopically labeled 57FeII. The slurries were...

Iron (Fe) phases are tightly linked to the preservation rather than loss of organic carbon (OC) in soil; however, during redox fluctuations, OC may be lost due Fe phase-mediated abiotic processes. This study examined role driving hydroxyl radical (•OH) formation and transformation cycles paddy soils. Chemical probes, sequential extraction, Mössbauer analyses showed that active species, such as exchangeable surface-bound low-crystalline minerals (e.g., green rust-like phases), predominantly...

Despite substantial experimental evidence of electron transfer, atom exchange, and mineralogical transformation during the reaction Fe(II)aq with synthetic Fe(III) minerals, these processes are rarely investigated in natural soils. Here, we used an enriched Fe isotope approach Mössbauer spectroscopy to evaluate how soil organic matter (OM) influences Fe(II)/Fe(III) transfer exchange surface soils collected from Luquillo Calhoun Experimental Forests this might affect mineral composition....

Properties of Fe minerals are poorly understood in natural soils and sediments with variable redox conditions. In this study, we combined 57Fe Mössbauer K-edge X-ray absorption spectroscopic (XAS) techniques to assess solid-phase speciation along the vertical gradients floodplains, which exhibited a succession oxic, anoxic, suboxic-oxic zones increasing depth profiles. The incised stream channel is bounded on east by narrow floodplain steep hillslope, west broad floodplain. eastern...

Iron (Fe) minerals constitute a major control on organic carbon (OC) storage in soils and sediments. While previous research has mainly targeted Fe (oxyhydr)oxides, the impact of sulfides their subsequent oxidation OC dynamics remains unresolved redox-fluctuating environments. Here, we investigated dissolved matter (DOM) FeS how its may alter retention nature DOM. After anoxic reaction DOM with FeS, preferentially removed high-molecular-weight nitrogen-rich compounds promoted formation...

Currently, the photodetectors (PDs) assembled by vertically aligned nanostructured arrays have attracted intensive interest owing to their unique virtues of low light reflectivity and rapid charge transport. However, in terms inherent limitations caused numerous interfaces often existed within arrays, photogenerated carriers cannot be effectively separated, thus weakening performance target PDs. Aiming at resolving this critical point, a high-performance ultraviolet (UV) PD with...

The poorly crystalline ferrihydrite (Fh) is often associated with organic matter (OM) and metal(loid)s, such as arsenic (As). transformation of Fh to more stable and, hence, less reactive phases catalyzed by the surface reaction Fe(II). However, little known regarding impact various specific OM types co-existence As on secondary mineralization Fh. Accordingly, we explored extent resulting minerals Fe(II)-induced [As(III)-adsorbed] OM–Fh adsorption co-precipitation complexes, which were...

Abstract Seismic anisotropy can provide valuable constraints for the study of subduction zone dynamics. This presents a high‐resolution 3‐D azimuthally anisotropic shear wave velocity model down to 230 km beneath Alaska via ambient noise tomography and gradiometry method. The reveals layered patterns related tectonics. wave's fast directions in Aleutian fore‐arc region exhibit trench‐parallel, trench‐normal, trench‐normal variation relative trench trend with increasing depth. pattern may be...

Abstract Aramid cord fabric, a novel polymer composite material, exhibits high strength‐ and modulus, low thermal shrinkage, excellent dimensional stability. It has broad applications in marine development, oil exploration, transportation, specialized tires, other sectors. Despite its extensive use, research into the superhydrophobic of aramid fabrics remains sparse. Consequently, development fabric material is essential. This study introduces straightforward method involving application...

Environmental context Organo–mineral associations represent a fundamental process for stabilising organic carbon in soils. In this study, we employed scanning transmission X-ray microscopy–near edge absorption fine structure (STXM-NEXAFS) spectroscopy at C, Al and Si K-edges as well Ca Fe L-edges to conduct submicrometre-level investigations of the C with mineral components soils from reduced environments. This study provides first insights into organo–mineral environments shows progress...