Iron as a precursor of aggregation and vector of organic carbon to sediments in a boreal lake

• DOI: 10.1007/s10533-024-01184-6
• Publication Date: 2024-10-15T07:01:59Z
• Authors: Simon David Herzog; Viktoriia Meklesh; Margarida Soares; Ulf Olsson; Per Persson; Emma Sofia Kritzberg
• Keywords: Carbon fibers

Abstract While organic matter (OM) interactions in the water column prevent iron (Fe) precipitation and sedimentation, Fe also acts as a precursor of aggregation vector OM to sediments. This study aims characterize Fe–OM understand role promoting transport OM. Samples were collected from water, settling material, sediment along gradient starting inlet continuing offshore within boreal lake. speciation was determined using X-ray absorption spectroscopy (XAS), chemical composition assessed Diffuse reflectance infrared Fourier transform (DRIFT IR) Nuclear magnetic resonance (NMR). The results show decrease concentrations with increasing distance inlet. Winter sampling revealed shift dominance organically complexed an increase Fe(oxy)hydroxide, accompanied by loss aromatic carboxylate function Summer no significant changes gradient, Fe(oxy)hydroxide carbohydrates dominating phase. Interestingly, particles surface sediments dominated Fe(oxy)hydroxides aliphatic We propose that phototransformation may be important process influences interaction between and, consequence, their fate spatial gradient. Our suggests photochemically induced groups, reflected increased carbohydrate-to-carboxylate ratio particularly winter, generally lower levels during summer. Loss promotes formation Fe(oxy)hydroxides, which turn, facilitates sinking OM, components. These insights contribute broader understanding carbon cycling storage lakes. Future studies should assess significance photochemical processes burial it how change given trends northern regions.