Determining appropriate techniques for assessing the bioavailability of PCBs from field-collected sediments

Chemical means of determining the bioavailability of contaminants from sediments can be a valuable tool when compared to a traditional bioaccumulation assay using live organisms. Two chemical alternatives, 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). Lumbriculus variegatus were exposed to three polychlorinated biphenyl (PCB)-contaminated field sediments to determine biota-sediment accumulation factors (BSAFs) and body residues. Sum PCB BSAFs ranged from 1.18 to 2.47. The PCB concentration in biota was positively correlated to that in sediment, in the rapidly desorbing fraction, and on the fiber across sediments. Results showed EPT was acceptable for estimating bioavailability from the tested sediments; however, it may overestimate PCB bioavailability from sandy sediment. Both Tenax extraction and Matrix-SPME could reduce variability among the sediments, however, Matrix-SPME, which directly measured sediment pore water concentrations, provided an overall better estimation.