Occurrence of DDTs in riverine water of the Pearl River Delta: Concentration levels and impact to the coastal-ocean environment

A large-scale sampling program was conducted to collect water samples at eight major riverine runoff outlets of the Pearl River Delta (PRD) monthly from March 2005 to February 2006. DDTs (sum of o´p-DDT, o´p-DDE, o´p-DDD, p´p-DDT, p´p-DDE, and p´p-DDD) were measured in ninety-six water samples, and concentrations of the DDTs were in the range of 1.08-19.6 ng/L with an average concentration of 3.89 ng/L. Compositional profiles of DDTs indicated new input sources in the study area, but the results indicated that the contribution of dicofol to the current DDTs pollution in the riverin water was relatively small, considering the amount of DDTs historically generated in the region. Furhtermore, the results showed the total input of DDTs to the coastal-ocean environment was 1030 kg from the eight outlets of the PRD, indicating that DDTs input from terrestrial sources continutes to have serious impact to the coastal-ocean environment and human health.