Selective retention of extracellular polymeric substances induced by adsorption to and coprecipitation with ferrihydrite

• EPS-C, N, P preferentially retained during adsorption and coprecipitation with Fh. EPS mass uptake selective fractionation opposite for the two formation pathways. Proteins acidic polysaccharides selectively in complexes. Lipids polysaccharide components coprecipitates. Differential sorption process of Fh revealed by 2D-COS-FTIR. Recent work shows that microbially-derived compounds constitute a significant fraction soil organic matter (OM) pool. These include extracellular polymeric substances (EPS) whose can far exceed total microbial cell biomass. Sorption to minerals occurs via contributes preservation OM environment. Little is known, however, about mechanisms retention different constituents on iron (oxyhydr)oxides, especially versus these reactive phases. This study examines how interacts ubiquitous (oxyhydr)oxide ferrihydrite whether EPS-mineral association pathways affect retention, thus mobility fate We use several complimentary techniques i) examine EPS-carbon, EPS-nitrogen EPS-phosphorus fractionation, ii) visualize spatial relationships between biomolecular classes using confocal laser scanning microscopy (CLSM), iii) determine EPS-C speciation chemical X-ray photoelectron spectroscopy (XPS) near-edge absorption fine structure (NEXAFS), iv) functional group interactions Fourier transform infrared (FTIR) combined two-dimensional correlation (2D-COS) analysis. Results show does not change mineralogy, as main mineral phase association, but it substantially increases particle size EPS-ferrihydrite. A substantial difference associated observed experiments at an initial molar C/Fe ratio >1. The EPS-N relatively enriched process, while more near-complete EPS-P are fixed process. XPS results surface formed through protein-like components, whereas, polysaccharide-like which visually confirmed CLSM images. NEXAFS reveal carboxylic/amide C-containing adsorption, aliphatic O-alkyl coprecipitation. 2D-FTIR-COS indicate O groups adsorbed faster than amide carboxylate groups, trend observed. findings from this pathway EPS-ferrihydrite associations effects may carbon (C), nitrogen (N) phosphorus (P) soils. new insights behaviour mineral–water interface might be used evaluate like stabilized (oxyhydr)oxides EPS-iron couplings reactivity cycling natural environments.