Residues of toxaphene decrease in estuarine fish after removal of contaminated sediments

To determine if toxaphene residues in edible fish tissue decreased after removal of contaminated sediments from an estuarine site in 1999, 51 composite samples representing six finfish species were collected in 2001 and analyzed using gas chromatography with electron capture and negative ion mass spectrometric detection. The grand mean total toxaphene residue concentration on a wet weight basis (ΣTOX_wet) was 1,400 ± 3,500 ng g⁻¹ (range: < 18 to 18,000 ng g⁻¹) and was positively correlated with extractable lipid. On a lipid basis, the mean ΣTOX_lip was 26 ± 33 μg g¹, which decreased with increasing distance from the study site. Although benthically-oriented species, such as spot (Leiostomus xanthurus) and striped mullet (Mugil cephalus), exhibited higher mean ΣTOX_wet than those of higher trophic level fish, mean ΣTOX_lip were not significantly different among species. The grand mean ΣTOX for 2001 was 3.8 (wet) and 2.6 (lipid) times less than corresponding preremedial action (1997) concentrations, suggesting that bioavailable toxaphene residues in this system have been reduced. Forage species, such as croaker (Micropogonias undulatus), mullet, and spot, preferentially accumulate toxaphene residues in this system and may serve as vectors of organochlorine contaminants in the estuarine and coastal ocean food web.