Does Tenax Extraction Based Desorption Measure (bio)availability of Sediment-associated Contaminants? Ices Cm 2007/j:14

Tenax-resin has been originally developed for grabbing volatile organic compounds from gases. The resin is a porous polymer (2,6-diphenyl-p-phenylene oxide) and it has low affinity for water (floats on the surface). It has high affinity for hydrophobic organic contaminants (HOCs), thus capturing them efficiently from water. On the other hand, the HOCs can be quite easily be extracted from Tenax. Due to these properties Tenax has been applied to measure desorption of HOCs in sediment(and soil-) water systems. The Tenax extraction has indicated that HOCs sorbed to sediments can be modeled to belong to 2 or more compartments on the basis of rate of desorption (for example rapid, slow and very slow fractions). Following this it has been anticipated that mainly the rapidly desorbing fraction, obviously containing also the freely dissolved fraction, would be bioavailable. Several studies have been conducted to determine if Tenax extraction based desorption could be used to predict bioavailable fraction in sediments. In many cases the laboratory studies indicated that there is a relationship between the size of rapidly desorbing fraction or rate constant for the rapid fraction and bioavailability. However, there are some issues that we must be aware when using Tenax extraction. For example, it appears that ecological factors, such as species life and feeding habits affect the bioavailability in ways that cannot be detected by Tenax extraction.