Occurrences and fate of DDT principal isomers/metabolites, DDA, and o,p'-DDD enantiomers in fish, sediment and water at a DDT-impacted superfund site

In the 1950s and 60s, discharges from a DDT manufacturing plant contaminated a tributary system of the Tennessee River near Huntsville, Alabama, USA. Regulatory action resulted in declaring the area a Superfund site which required remediation and extensive monitoring. Monitoring data collected from 1988, after remediation, through 2011 showed annual decreases approximating first-order decay in concentrations of total DDT and its six principal congeners (p,p'-DDT, o,p'-DDT, p,p'-DDD, o,p'-DDD, p,p'-DDE and o,p'-DDE) in filets from three species of fish. As of 2013, these concentrations met the regulatory requirements of 5 mg/kg or less total DDT for each fish tested. The enantiomer fractions (EF) of chiral o,p'-DDD in smallmouth buffalo and channel catfish were always below 0.5, indicating preferential decay of the (+)-enantiomer of this congener; this EF did not change significantly over 15 years. The often-neglected DDT metabolite p,p'-DDA was found at a concentration of about 20 μg/l in the ecosystem water. •Total DDT in contaminated smallmouth buffalo decayed from 90 to 5 mg/kg over 23 years.•Largemouth bass accumulated much lower levels of all DDT congeners than did other fish.•p,p'-DDT, the most concentrated congener in sediment, biotransformed to p,p'-DDD in fish.•Enantiomer fractions of o,p'-DDD were non-racemic in both sediment and fish.•The unusual DDT metabolite DDA was found at about 20 μg/l in the ecosystem water. This article presents 24 years of monitoring data for DDT and its isomers and metabolites that show successful remediation of an aquatic ecosystem severely contaminated by waste from a DDT plant.