Natural organic matter (NOM), a heterogeneous mixture of substances largely of terrestrial and microbial origin, can affect the speciation, transport, and bioavailability of organic and inorganic pollutants in natural aquatic environments. A number of NOM constituents can form strong complexes with problematic metalloids and metal oxides such as arsenic (As), selenium (Se), and strontium (Sr). To help elucidate specific NOM-metal interactions, the RO isolate from Suwannee River NOM was fractionation using resin adsorption chromatography. Two resins with different characteristics (XAD-4 and XAD-8) were used to fractionate the NOM into hydrophilic (HPI), hydrophobic (HPO) and transphilic (TPH) portions. The eluate from XAD-8 resin corresponds to the HPO portion, the eluate from XAD-4 resin yields the TPH portion and the effluent passing through both columns contains the HPI portion. The NOM fractionations were characterized with ultraviolet/visible (UV/Vis) spectroscopy and by excitation and emission matrix (EEMs) fluorescence. Environmentally relevant concentrations of trace metals were added to the fractionated NOM. Addition of these metal species to the NOM fractions results in changes of UV absorption and fluorescence properties of the NOM indicating specific adsorption mechanisms to be presented. Ongoing studies include characterization of the interactions between size fractionated NOM and As, Se, and Sr to better understand specific metal ion-NOM interactions towards development of NOM based adsorbents for toxic metal remediation.

Light adsorption and fluoresence properties of  fractionated natural organic matter upon loading with arsenic and selenium

2019 Spring National Meeting

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