Evaluation of organochlorine contamination in Indo-Pacific humpback dolphins (Sousa chinensis) from the Pearl River Estuary, China

Organochlorine compounds, including polychlorinated biphenyls (PCBs), dichlorodiphenyl trichloroethane (DDTs), hexachlorocyclohexane (HCHs), chlordanes (CHLs) and hexachlorobenzene (HCB) were analyzed in blubber samples collected from fifteen Indo-Pacific humpback dolphins (Sousa chinensis) stranded in the Pearl River Delta during the period from 2004 to 2009. In general, the magnitude of the mean concentrations is: ∑ DDTs > ∑ PCBs > ∑ HCHs > ∑ CHLs > HCB. DDT levels found in this study were very high, with the ΣDDT ranging from 845 to 179000 ng/g wet weight. Of particular importance is the fact that new inputs from diverse sources still exist in the Pearl River Delta. ∑ PCBs ranged from 123 to 10,200 ng/g wet weight. More studies are necessary for a better understanding of these organochlorine contaminants and their impact on the conservation of humpback dolphins residing in the Pearl River Estuary waters.

► The mean levels of ∑ DDTs > ∑ PCBs > ∑ HCHs > ∑ CHLs > HCB in pink dolphins from PRE
► ∑ PCBs were relatively low compared to those in highly industrialized areas.
► ∑ DDTs were recorded with very high levels of 845.30 to 178598.76 ng/g w.w.
► The high DDT/DDE may imply that fresh DDT inputs still exist for PRE waters.
► More OCs data need to be obtained in dolphins from PRE for better conservation.