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EFFECT OF NON-TARGET ORGANICS ON ORGANIC CHEMICAL TRANSPORT
Citation:
Enfield*, C G., B. K. Lien*, AND A L. Wood*. EFFECT OF NON-TARGET ORGANICS ON ORGANIC CHEMICAL TRANSPORT. C.E. Clapp, M.H.B. Hayes, et al (ed.), Humic Substances and Chemical Contaminants, Chapter 23. Soil Science Society of America, Madison, WI, , p. 471-487, (2001).
Description:
To improve our standard of living, man has synthesized organic compounds for use in products considered essential for life. These compounds are having and will continue to have a significant impact on the terrestrial environment. Understanding organic chemical transport through soils, sediments and subsurface geologic materials is requisite for making intelligent decisions on environmental exposure, risk analysis, and remedial actions. The enormous cost associated with ground water remediation and the utilization of groundwater as a limited resource underscores the importance of understanding the phenomena that can affect organic chemical transport. Many physical, chemical, and biological processes govern the transport of organic chemicals through geologic materials. Most models assume that concentrations of the chemicals in solution are low relative to its solubility, that the chemicals in solution act independently of each other, and that sorption is driven by favorable thermodynamics of solute removal from solution through sorption on a stationary unchanging hydrophobic phase. These assumptions appear to be reasonable in most agronomic environments where applied concentrations are low unless there is a significant amount of dissolved organic carbon. However, as concentrations increase chemicals in solution begin to interact with each other s cosolvents at high concentrations, micelles are occasionally formed adding a mobile organic phase. Experimental data has shown that some chemicals react with stationary phase changing the properties of the stationary phase. Some reactions convert a normally hydrophilic stationary to a hydrophobic stationary phase while some chemicals reduce the interfacial tension beween the phase increasing the mobility of entrapped organic fluids. The objective of this chapter is to develop a theory showing phase interactions and then illustrate the theory with selected examples related to environmental characterization and remediation. Finally, flow stability, which is not covered by the theory, is discussed.