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- Title
Effect of Oxic State on Nonpolar Organic Contaminant Distribution, Mobility, and Bioavailability in Estuarine Sediments.
- Authors
Pedersen, Joel A.; Schweitzer, Linda E.; Lin, Chen-Hung Michael; Suffet, I. H.
- Abstract
Abstract. Dissolved and particle-associated natural organic matter plays an important role in nonpolar organic chemical distribution, mobility, and bioavailability in sediment environments. We investigated the influence of oxic state on the association of a model hydrophobic organic chemical (HOC), 2,2',4,4'-tetrachlorobiphenyl (TeCB), with dissolved and particle-associated organic matter in estuarine sediments. Site-specific distribution data were used to model the effect of oxic state on diffusive flux of TeCB across the sediment-water interface. Additional experiments examined the role of oxic state in TeCB bioavailability to a deposit-feeding epibenthic echinoderm. Aeration of estuarine sediment pore waters induced a negligible change to greater than an order of magnitude decrease in the dissolved organic carbon (DOC)- water distribution coefficient, K pwdoc , in all but one system examined. Correspondingly, oxidation of sediment solids effected a negligible to 0.5 log unit decrease in the particle associated organic carbon-water distribution coefficient, K oc . These results indicate that aeration of anoxic estuarine sediments induced by dredging, bioturbation, or storm events may result in release of HOCs from particle-associated and dissolved organic matter, increasing the concentration of the truly dissolved compound. Model simulations indicated that oxygenation of anoxic sediments would result in a 34-100% increase in TeCB diffusive flux. Pore water dissolved organic matter (DOM) facilitated TeCB transport across the sediment-water interface and increased diffusive flux by up to a factor of 1.7. A sensitivity analysis indicated that facilitation of diffusive transport by DOM would be significant in the systems under investigation when log K pwdoc exceeded approximately 5.7. Therefore, disturbing anoxic sediments can mobilize HOCs. In bioaccumulation assays using sea urchins, TeCB bioavailability temporarily increased after anoxic sediments were disturbed and aerated, but long-term bioavailability remained unaltered when sediment reduction potential returned to the level of the unaerated control.
- Subjects
ORGANIC compounds; POLLUTANTS; ADSORPTION (Chemistry); ESTUARINE ecology; SEDIMENT microbiology; ECOSYSTEM health
- Publication
Israel Journal of Chemistry, 2002, Vol 42, Issue 1, p109
- ISSN
0021-2148
- Publication type
Article
- DOI
10.1560/569Q-NH11-LXPM-KH1Q