Extraction of sediment-bound chlorinated organic compounds: implications on fate and hazard assessment

Five methods were used for the extraction of hexachlorobutadiene and chlorobenzenes from a contaminated estuarine sediment. The following extraction methods were used: Soxhlet extraction, sonication and solvent extraction, sequential solvent extraction, saponification and solvent extraction, and supercritical fluid extraction. Soxhlet extraction resulted in better contaminant extraction efficiency and reproducibility. Most of the problems associated with the extraction methods were related to high water content and the inherent heterogeneity of the sediment samples. Drying and grinding of the sample greatly improved both extraction efficiency and reproducibility. Analyses of wet sieved and fractionated sediment samples indicated that the contaminants are not evenly distributed throughout the sediment organic fraction but rather predominate in the larger particle sediment fraction. The implications of quantification difficulties of sediment contaminants on the environmental fate and hazard assessment are discussed.