Hydrophobic organic contaminants, HOCs

Abstract Partitioning of two hydrophobic organic contaminants (HOCs), phenanthrene... 

Dissolved organic matter (DOM) is ubiquitous to natural waters and is known to undergo a number of reactions of environmental interest. Among these reactions neutral hydrophobic organic contaminants (HOCs) can partition into or be bound to DOM. This process can significantly alter the... 

The Linear Partitioning Model. Several conceptual and empirical models have been proposed to quantify sorption of hydrophobic organic contaminants (HOCs) by soils and sediments. The simplest of these is the linear partitioning model, in which the solid-phase solute concentration, is assumed to be directly proportional to the aqueous-phase solute concentration, Q i.e.,... 

The mobility and bioavailability of hydrophobic organic contaminants (HOCs) in aquatic systems, sueh as PAHs, depend on desorption of these compounds from the solid phase to water. In several studies a two-stage desorption kinetics were observed, in which rapid desorption was followed by slow release [40, 41]. Furthermore, a subsequent very slow desorption stage was defined by Comelissen et al. [42], further supporting the hypothesis that bioavailability is limited by mass transfer kinetics [43]. The slow and very slow desorption of contaminants from natural sorbents has gained much attention, because this could be a severe problem in remediation that challenges concepts concerning cleanup standards and risks [29]. 

Temperature is a key parameter for controlling H or thereby strongly influencing air-water partitioning of chemicals in the environment. A good deal of effort is expended in deducing temperature-dependent H for contaminants of concern, which is not an easy task for low-polarity hydrophobic organic chemicals (HOCs) with poor solubility. 

In the following the contaminant is abbreviated as HOC (hydrophobic organic chemical), the carrier as DOC (dissolved organic carbon) and the carrier bound contaminant as HOC-DOC. Of course, the model is not restricted to the transport of only these particles but may also be applied to others. 

In soil-aqueous systems, the hydrophobic interiors of nonionic surfactant micelles can compete strongly with soil organic matter as a compartment for the partitioning of HOCs. Surfactant micelles in such systems can markedly increase the bulk solution fraction of the total HOC mass, and micellar surfactant flushing has consequently been considered as a potential means for remediating soils contaminated with sorbed HOCs (4-6). Relatively little is known, however, about the physicochemical interactions of surfactants with HOCs and soil. 

---