Bioassay-directed identification of toxicants in sediments of Liaohe River, northeast China

Abstract Contaminants accumulated in sediments may directly harm benthic organisms, however, the specific contaminants responsible for adverse effects have been poorly described. In this study, a bioassay-directed analysis combined with toxicity tests and chemistry analysis was conducted to determine the compounds eliciting the greatest toxicological effect in the sediments in Liaohe River, northeast China. A total of 24 sediment samples were examined to determine their acute toxicity to midge Chironomus tentans ( C. tentans ). Of these samples, 15 exhibited significant toxicity, with a mortality of 23%–93% (p  1 TU. The significant correlation between the TUs of pyrethroids and the mortality of C. tentans (r 2  = 0.74, p