MP11 Advances in Bioaccumulation Assessment
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(GUN-1117-815203) Bioavailability assessment of organic contaminants in limnic sediments using in vitro gut fluid extraction.

Gunnarsson, J.S.G¹, Kukkonen, J.V.K², Weston, D.P.², Landrum, P.F.³, ¹ Stockholm University, Sweden² University of Joensuu, Finland³ University of California Berkeley, CA, USA

ABSTRACT- The objective of this study was to measure the bioavailability of sediment-associated organic contaminants with a recent in vitro technique, that uses natural gut fluid collected from a polychaete worm, and to compare it to the in vivobioaccumulation kinetics by Lumbriculus variegatus and Diporeia spp. Seven limnic sediments of different organic carbon contents and geochemical characteristics were collected from the Great Lakes and spiked with four radiolabeled organic contaminants: benzo(a)pyrene, pyrene, 2,2',4,4',5,5'-hexachlorobiphenyl and 3,4,3',4'-tetrachlorobiphenyl. Sediment chemical characterization was done by measurement of total organic carbon (OC), organic nitrogen, soot carbon, particle size distribution, phytopigments, total and bioavailable amino acids, and NaOH extractable OC. In vitro gut fluid extraction was done by incubating the contaminated sediments for 3h with gut fluid isolated from the polychaete Arenicola brasiliensis and then measuring the fraction of contaminant solubilized in the fluid. Correlation tests were done between gut fluid extraction efficiency (GFEE) and bioaccumulation factors (BAF), (BSAF), uptake clearance rates, sediment characteristics, and desorption measurements using Tenax extractions. The gut fluid extraction was correlated to the desorption rate of the compounds and to the organic carbon normalized uptake clearance rate. The gut fluid extractions were positively correlated to the BAF of all contaminants except for BaP, showing that this relatively simple and rapid technique, was in most cases an excellent predictor of the fraction of sediment-contaminant that was bioavailable to Lumbriculus variegatus and Diporeia spp.

Key words: sediment, organic contaminants, bioavailability, in vitro digestive fluid extraction