R6 PM Bioavailability
Thursday, 17 November 2005: 1:50 PM - 5:30 PM in 324-326

(YOU-1117-237577) Chemical Approaches for Assessing Bioavailability of Hydrophobic Contaminants in Sediment.

You, J¹, Landrum, P², Lydy, M¹, ¹ Southern Illinois University, Carbondale, IL, USA² NOAA, Great Lakes Environmental Research Lab, Ann Arbor, MI, USA

ABSTRACT- To address the bioavailability of hydrophobic contaminants in sediment, biota-sediment accumulation factors (BSAF) are usually calculated using tedious and expensive bioassays. Due to the existence of resistant, slowly reversible, binding compartments within the sediment matrix, bioaccumulation of contaminants from sediment can not be directly estimated from their total concentrations in sediment, but should be better estimated from contaminant concentrations in the pore water or the rapidly desorbing fraction from sediment. Therefore, two chemical approaches, the determination of rapidly desorbing fraction with tenax absorbent and the determination of pore water concentration with matrix solid phase microextraction (M-SPME), were evaluated as alternatives for assessing bioavailability of five hydrophobic contaminants with different characteristics (2,2^,,4,4^,,5,5^,-hexachlorobiphenyl, permethrin, DDE, phenathrene and chloropyrifos) in sediments with different organic carbon contents. The results were also compared to the BSAF measured directly from 14-day and 28-day oligochaete Lumbriculus variegatus bioaccumulation tests. After a 7-day aging period, sediments spiked with 14C-labelled compounds were tested using tenax absorbent, SPME fiber and L. variegatus. The possibility and accuracy of the rapidly desorbing fraction measured from the tenax approach, and pore water concentration detected from the M-SPME approach for predicting BSAF values were evaluated for the five target compounds and the correlation of rapidly desorbing fraction and pore water concentration with Kow of chemicals and organic carbon in sediment were also examined. The relative costs of the different approaches were also compared.

Key words: bioavailability, sediment, Tenax desorption, M-SPME