Extractability of dioxins from suspended substances in distributed water

摘要

The extractability of dioxins from suspended substances (SS) in distributed water was evaluated. Dioxins adsorbed on the collected SS were extracted by pressurized liquid extraction with various solvents. High-polarity solvents (acetone, alcohols) extracted considerably higher amounts of some lower-chlorinated dibenzo-p-dioxins (LoCDDs) than did low-polarity solvents (dichloromethane, toluene), whereas the extracted amounts of higher-chlorinated dibenzo-p-dioxins (HiCDDs) were roughly the same, regardless of the solvent. The extractability of the LoCDDs depended on the isomer. Daily variations in quantities for PCDDs, organic matter (OM), and iron in the SS were examined, and the results suggested that in the SS, LoCDDs and HiCDDs were associated, respectively, with raw water-derived organic matter and microparticles sequestered in iron oxy(hydr)oxide floc. It was also suggested that the low extractability of certain congeners was not attributable to the enormously coexisting ferric compounds but was probably attributable to OM with which they strongly associate.