Comparing bulk extraction methods for chemically available polycyclic aromatic hydrocarbons with bioaccumulation in worms

The purpose of this study is to evaluate different techniques for assessing the availability of polycyclic aromatic hydrocarbons (PAHs) in contaminated sediments. This goal was achieved by comparing results from 28-day uptake experiments by Nereis virens and Lumbriculus variegatus with PAHs extracted by three non-exhaustive extraction methods using: n-Butanol (BuOH, 100%), an aqueous solution of hydroxypropyl-beta-cyclodextrin (HPCD) and a surfactant solution of Brij700 (B700). Our results highlight the importance of considering both the PAH level in sediments and the molecular size of PAHs when attempting to predict their bioaccumulation in a biological sampler like worms using a solid/liquid extraction method. The surfactant B700 solution was quite successful to predict PAH bioaccumulation when exposed to unspiked highly contaminated sediments (25-5700 mu g g(-1)). When low contaminated sediments (0.06-11 mu g g(-1)) were used, HPCD and BuOH were better extractants for estimating bioaccumulation whereas B700 appeared to be too mild an extractant for most samples. Our results illustrate the interest and difficulties in finding an adequate chemical predictor for PAH bioavailabilty, particularly because PAH concentrations and sequestration processes play a determining role in the quality of results. Because B700 is not expansive and extraction solutions are easy to prepare, an extraction procedure involving this surfactant is proposed as a reliable predictor for aged highly contaminated sediments.