Isomers of Dechlorane Plus in an aquatic environment in a highly industrialized area in Southern China: Spatial and vertical distribution, phase partition, and bioaccumulation

Dechlorane Plus (DP) was determined in aquatic environment including sediment, sediment core, water, and fish species in a highly industrialized area in Pearl River Delta, South China. DP was analyzed in sediments and water at concentration ranging from 0.08 to 19.4 ng/g dry weight and from 0.24 to 0.78 ng/L, respectively. DP was detected in 80% of fish samples with concentration between undetectable level to 189 ng/g lipid weight. DP levels were significantly higher in the top layer (depth less than 36 cm with concentration ranging from 0.35 to 57.6 ng/g) than in the lower section (concentration ranging from 0.02 to 0.72 ng/g), indicating an increase in DP contamination in recent years. The fraction of anti-DP in the sediment and water are close to that in the technical mixtures implying no stereospecific degradation occurring. An enrichment of syn-DP was observed in three fish species suggesting that a stereospecific metabolism of anti-DP and/or stereoselective uptake of syn-DP occurring in fish species. The calculated BSAFs are 0.024, 0.037, and 0.10 for DP, in mud carp, nile tilapia, and plecostomus, respectively, suggesting relatively low bioavailability of DP isomers in the sediments.