文摘
The complex mixture of dissolved organics in oil sands process-affected water (OSPW) is acutely lethal to fish at environmentally relevant concentrations, but few bioconcentration factors (BCFs) have been measured for its many chemical species. Japanese medaka (Oryzias latipes) were exposed to 10% OSPW, and measured BCFs were evaluated against predicted BCFs from octanol–water distribution ratios (DOW) and phospholipid membrane–water distribution ratios (DMW). Two heteroatomic chemical classes detected in positive ion mode (SOp>+p>, NOp>+p>) and one in negative mode (O2p>–p>, also known as naphthenic acids) had the greatest DMW values, as high as 10 000. Estimates of DMW were similar to and correlated with DOW for Op>+p>, O2p>+p>, SOp>+p>, and NOp>+p> chemical species, but for O2p>–p> and SO2p>–p> species the DMW values were much greater than the corresponding DOW, suggesting the importance of electrostatic interactions for these ionizable organic acids. Only SOp>+p>, NOp>+p>, and O2p>–p> species were detectable in medaka exposed to OSPW, and BCFs for SOp>+p> and NOp>+p> species ranged from 0.6 to 28 L/kg, lower than predicted (i.e., 1.4–1.7 × 10p>3p> L/kg), possibly because of biotransformation of these hydrophobic substances. BCFs of O2p>–p> species ranged from 0.7 to 53 L/kg, similar to predicted values and indicating that phospholipid partitioning was an important bioconcentration mechanism.
