Availability of Organic and Inorganic Contaminants in Sediments

The definition of exposure and risk to contaminants in sediments depends upon access to those contaminants, the extent to which accessible contaminants are bioavailable and the extent to which contaminants accumulate in organisms of interest. This presentation will focus on efforts to understand and quantify these processes for both organic and inorganic contaminants. Recent research associating interstitial water concentrations of PAHs and PCBs to bioaccumulation in benthic organisms will be reviewed. This research has provided an increasingly strong basis for the use of interstitial water concentrations as an indicator of bioavailability, bioaccumulation and ultimately exposure and risk of these contaminants to the benthic community. Building on this basis, field deployable solid phase microextraction devices were developed and used to evaluate bioavailabilty and mobility of organic contaminants in sediments. The use of these devices to assess, in-situ, mechanisms and rates of chemical transport and the effectiveness of permeable containment or sorptive barriers (sediment caps) will be summarized. Similarly many of the critical species defining exposure and risk to inorganic contaminants are found in the interstitial water and the use of models and in-situ voltametric methods to assess these risks will also be discussed.