Bioavailability of PCBs from field-collected sediments: application of Tenax extraction and matrix-SPME techniques.

Two chemical approaches, Tenax extraction and matrix solid phase microextraction (matrix-SPME), were evaluated for their potential to improve the prediction of bioavailability by equilibrium partitioning theory (EPT) across sediments with various characteristics. Biota-sediment accumulation factors (BSAFs) and body residues were quantified by exposing Lumbriculus variegatus to three PCB-contaminated field sediments. The concentration of PCBs in biota was positively correlated to the total PCB sediment concentration, the PCB concentration in the rapidly desorbing fraction estimated using Tenax extraction, and the PCB concentration on the SPME fibers. Results showed EPT was acceptable for estimating bioavailability from the tested sediments with sum PCB BSAFs of 1.18-2.47; however, it overestimated PCB bioavailability from sandy sediment. Both Tenax extraction and matrix-SPME, which take sequestration into account, reduced variability in prediction of PCB bioavailability across sediments, including the sandy sediment, and could be used as cost- and time-efficient alternatives for bioassay. Matrix-SPME was considered the better technique due to its ability to directly predict PCB body residues in the exposed biota and its potential use with in situ applications in the field.