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(465) Properties of Natural Organic Matter Relevant to Considerations of Pollutant Transport and Transformations. Macalady, Donald1, 1 ABSTRACT- The complex group of substances called natural organic matter (NOM) and primarily composed of degraded organic detrital components, includes humic substances and several other operationally defined fractions and is ubiquitous in natural waters and soils. Considering NOM in a given environment as an unfractionated group of substances has several advantages in considerations of the influences of NOM on pollutants in soils, sediments and natural waters (as compared to studying fractions such as humic and fulvic acids). NOM is known to influence transport of hydrophobic chemicals through partitioning reactions and that of metal ions through complexation/chelation processes. NOM has strong influences on oxidation/reduction processes in aqueous systems, and is a powerful electron-transfer mediator. Finally, it affects the surface properties of soils, sediments and colloidal particles through adsorption to mineral surfaces. The use of operationally defined fractions of NOM in studies of these processes tends, at the least, to mask important differences among NOM samples from different environments and botanic origins. This paper details studies using unfractionated NOM samples in metal-complexation, adsorption and oxidation/reduction processes. Our studies use samples of NOM from a wide variety of sources. Each sample is characterized according to elemental composition as well as through ultraviolet and infrared absorption, nuclear magnetic resonance spectra, and acid-base characteristics. Attempts are then made to use these properties as indicators in efforts to achieve predictive algorithms for the observed interactions among NOM and contaminants. Key words: natural organic matter, pollutant transport, pollutant transformation, humic substances |
