Toxicity of creosote water-soluble fractions generated from contaminated sediments to the bay mysid

Creosote, a globally used wood preservative, is a complex mixture consistin g primarily of aromatic organic compounds (ACs). Creosote-derived ACs can p ersist for decades in aquatic sediments. Natural and anthropogenic activiti es may result in dissolution and resuspension of sediment-associated ACs. T hese processes were mimicked by generating a water-soluble fraction (WSF) f rom creosote-contaminated sediment (ERS) collected from a polluted site. Th e epibenthic mysid Mysidopsis bahia was exposed to five sublethal concentra tions of WSF for 7 days. The WSF significantly decreased dry weight gain an d proportion of gravid females (EC50 = 15 mu g/liter total identified ACs). Chemical analysis indicated that high-molecular-weight ACs (more than thre e aromatic rings) dominated the ERS, but were undetected in the WSF. Low-mo lecular-weight ACs (fewer than three aromatic rings) dominated the WSF. Com positional differences can thus result from fractionation processes and aff ect environmental fate and toxicity of the mixture. (C) 1999 Academic Press .