Natural organic matter (NOM) is a ubiquitous component of natural systems exhibiting a rich and diverse chemistry. NOM is strongly coupled to many elemental redox cycles and has important roles in processes as varied as the photochemical generation of hydrogen peroxide (H2O2) to acting as a sink for oxidative species such as hydroxyl radical (HO�). When Fe(II) is oxidized by H2O2, the presence of NOM alters both the kinetics of this reaction and also the nature of the intermediate oxidative species produced.1 This system has been studied using Suwannee River Fulvic Acid (SRFA) as a representative NOM under conditions typical of circumneutral aquatic systems. The reaction is shown to be substantially decelerated by the presence of SRFA, however, the product of the reaction shifts from an ill-defined higher-valence state Fe species to the highly reactive HO� as the SRFA concentration is increased, with the involvement of HO� confirmed using a selective phthalhydrazide assay coupled with competition experiments.2 When Fe(II) is oxidized in the presence of simple organic ligands such as citrate, ethylenediaminetetraacetate (EDTA) and diethylenetriaminepentaacetate (DTPA) analogous behaviour is observed, with a kinetic model assuming that HO� formation occurs only from organically-complexed Fe(II) able to quantitatively explain both the synthetic ligand and SRFA system. The significance of these results to organic matter transformations and Fe biogeochemistry throughout a watershed are also discussed, with the relative importance of this process declining as salinity increases.31. Miller, C. J.; Rose, A. L.; Waite, T. D. Geochim. Cosmochim. Acta 2009 , 73, 2758-27682. Miller, C. J.; Rose, A. L.; Waite, T. D. Environ. Sci. Technol. 2013 , 47, 829-8353. Miller, C. J.; Lee, S. M. V.; Rose, A. L.; Waite, T. D. Environ. Sci. Technol. 2012 , 46, 11078-11085

Influence of natural organic matter in the biogeochemistry of iron and associated generation of oxidative species

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.