Passive Sampling for the Assessment of Availability and Uptake of Hydrophobic Contaminants.

Polymer sorbents are increasingly used to assess the availability and effects of contaminants in the environment. Over the past several years we have developed and tested an in-situ profiling solid phase microextraction (SPME) passive sampler using polydimethylsilxane (PDMS) for the assessment of interstitial water concentrations of PAHs and PCBs.  The approach provides cm vertical resolution of interstitial water concentrations of hydrophobic organic compounds.  This resolution can provide average near surface interstitial water concentrations of PAHs to PCBs for comparison to body burdens in benthic or higher organisms as well as discrete concentration measurements that can be used to infer mechanisms and rates of contaminant migration.  The presentation will begin with an overview of the method, the status of technology transfer to commercial laboratories for routine implementation, and a summary of all measurements to date.  The cumulative database of measurements will be used to illustrate the effectiveness of using the field measured interstitial water concentrations to assess bioavailability of PAHs and PCBs.  Additional emphasis will be placed on ongoing studies not presented elsewhere including current studies in an ongoing assessment of bioaccumulation of PCBs in marine tubificids and PAHs in clams at two locations in California.   Some of these studies include a comparison of the SPME approach to simultaneous assessments using polyoxymethylene (POM) and polyethylene (PE) and an interlaboratory comparison of individual approaches.   Field measured profiles of discrete concentrations will also be used to infer rates and mechanisms of transport in both laboratory and field experiments. The use of the profiling approach to evaluate sediment cap performance will be summarized with examples from field measurements in Portland, OR, Seattle, WA,  Washington DC, and Hunter’s Point CA,