Iron isotopic fractionation driven by low-temperature biogeochemical processes

• Published in: Chemosphere (Oxford) Vol. 316; p. 137802
• Main Authors: YIN, Nang-Htay, Louvat, Pascale, Thibault-DE-Chanvalon, Aubin, Sebilo, Mathieu, Amouroux, David
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2023; Elsevier
• Subjects: Analytical chemistry; Bacteria - metabolism; Biogeochemical processes; Chemical Fractionation; Chemical Sciences; Ferric Compounds - chemistry; Fractionation; Iron - chemistry; Iron isotopes; Iron Isotopes - analysis; Iron Isotopes - metabolism; Isotopes; Ligands; Microbial uptake; Oxidation-Reduction; Temperature; Biogeochemical processes; Iron isotopes; Ligands; Fractionation; Microbial uptake; Iron isotopes Fractionation Biogeochemical processes Microbial uptake Ligands
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2023.137802

Iron is geologically important and biochemically crucial for all microorganisms, plants and animals due to its redox exchange, the involvement in electron transport and metabolic processes. Despite the abundance of iron in the earth crust, its bioavailability is very limited in nature due to its occurrence as ferrihydrite, goethite, and hematite where they are thermodynamically stable with low dissolution kinetics in neutral or alkaline environments. Organisms such as bacteria, fungi, and plants have evolved iron acquisition mechanisms to increase its bioavailability in such environments, thereby, contributing largely to the iron cycle in the environment. Biogeochemical cycling of metals including Fe in natural systems usually results in stable isotope fractionation; the extent of fractionation depends on processes involved. Our review suggests that significant fractionation of iron isotopes occurs in low-temperature environments, where the extent of fractionation is greatly governed by several biogeochemical processes such as redox reaction, alteration, complexation, adsorption, oxidation and reduction, with or without the influence of microorganisms. This paper includes relevant data sets on the theoretical calculations, experimental prediction, as well as laboratory studies on stable iron isotopes fractionation induced by different biogeochemical processes. Fig. 1 Overview of iron isotopes fractionation driven by low-temperature biogeochemical processes such as redox reaction (Δ56FeII-III), ligand-complexation (Δ56FeIII-ligands), alteration/dissolution (Δ56Fesolution-solid), abiotic mineral precipitation (Δ56FeII/III-mineral), bio-uptake (Δ56FeIII-cell), bio-sorption (Δ56FeII-biomass vs Δ56FeIII-biomass), microbial oxidation (Δ56FeII-III-FeOOH), biomineralization (Δ56FeII or III-mineral/cell) and dissimilatory iron reduction of iron minerals (Δ56FeFeIIaq-FeIIIreact and Δ56FeFeIIaq-BulkMineral). (DFOB-desferrioxamine B, FeOOH-oxyhydroxide minerals, Bact-bacteria, Hem-hematite, Fer-ferrihydrite, Goe-goethite, Mag-magnetite, Sid-siderite, Mack-mackinawite, Pyr-pyrite, and DIR-dissimilatory iron reduction). In the “Dissolution” box, light refers to the presence of light favoring photochemical reductive dissolution and dark refers to the absence of light favoring oxidative dissolution. The red outline of one symbol in the “Bio-ferrous oxidation” box corresponds to the calculation of Δ56Fe between FeIIaq and FeIII on cell surface while the rest of calculation focused between FeII–FeIII and precipitated FeIII minerals. In the “DIR” box, the open symbol with black outline corresponds to the abiotic hematite experiment conducted in the presence of Si at pH7 in comparison to the experiments without Si. Error bars represent 2SD experimental error and. Detailed values and corresponding references for each process are given in Tables 1–3. [Display omitted] •Extent of Fe isotope fractionation depends on different geochemical processes.•Source signature of the original Fe minerals can be the primary control.•Limitations due to overlapping signatures between abiotic and biotic influences.•Reconciling the discrepancies observed between predicted and experimental values.•Microbial driven fractionation at inter/extracellular levels for future direction.