Impact of Sorption to Dissolved Organic Matter on the Bioavailability of Organic Chemicals
Dissolved organic matter (DOM) is ubiquitously present in the aquatic environment as well as in soil and sediment pore water. Partitioning-based techniques have generated better insights into the influence of different DOM structural features on sorption
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Contents 1 Introduction 2 Sorption of Organic Chemicals to DOM 3 Impact of Sorption to DOM on the Bioavailability of Organic Chemicals 3.1 Bioaccumulation 3.2 Biodegradation 4 Concluding Remarks References
Abstract Dissolved organic matter (DOM) is ubiquitously present in the aquatic environment as well as in soil and sediment pore water. Partitioning-based techniques have generated better insights into the influence of different DOM structural features on sorption for hydrophobic chemicals, but the prediction of pH-dependent sorption for polar and ionisable chemicals remains problematic. Sorption to DOM can reduce the apparent rate of uptake and extent of accumulation of hydrophobic chemicals, although sorption to DOM may in some cases enhance diffusive transport of the contaminants and thereby increase uptake rates during bioaccumulation. Similarly, DOM can act as a surfactant to increase the rate of solubilisation and microbial uptake of soil-sorbed chemicals and therefore their rates of biodegradation. The impact of DOM structure is, however, more complex than can be captured by simple organic carbon-based approaches. In particular, exploration of the influence of condensed aromatic structures in DOM, often referred to as dissolved black carbon, would probably yield better insights into their impact on the bioavailability of high molecular weight PAHs and other hydrophobic compounds. More studies of
J. R. Parsons (*) Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands e-mail: [email protected] Jose Julio Ortega-Calvo and John Robert Parsons (eds.), Bioavailability of Organic Chemicals in Soil and Sediment, Hdb Env Chem, DOI 10.1007/698_2020_520, © Springer Nature Switzerland AG 2020
J. R. Parsons
the sorption of polar and ionisable chemicals to DOM would also increase our understanding of its potential impact on the bioavailability of such chemicals. Keywords Bioaccumulation, Biodegradation, Dissolved organic matter, Passive sampling, Sorption
1 Introduction Dissolved organic matter (DOM) is operationally defined as the fraction of organic matter in water which can pass through a 0.22–0.7 (often 0.45) μm filter. DOM is often referred to as dissolved organic carbon (DOC) although it also contains important fractions of organic nitrogen and phosphorus. Dissolved organic matter (DOM) is ubiquitously present in the aquatic environment as well as in soil and sediment pore water. The concentration and composition of DOM play a significant role in natural biogeochemical processes but can also have an important impact of the fate and effects of environmental pollutants. Although DOM in the broad sense includes all dissolved organic chemicals, it is often taken to refer to macromolecular, humic substances related components. In general, these humic substances comprise around 50% of the total DOM content of typical river water [1]. The concentration and composition of DOM are highly variable, depending on the source of the organic components, on environmental condition
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