[Distribution Characteristics and Ecological Risk Assessment of HCHs and DDTs in Surface Water Bodies in Xinxiang]

In order to investigate the distribution characteristics and ecological risk of HCHs and DDTs in the surface water of Xinxiang, 18 surface water samples were collected from from Xinxiang and the concentrations of HCHs and DDTs were determined. The ecological risk of HCHs and DDTs was evaluated using the overlapping areas of probability density function and safety threshold methods. The results showed that the levels of total HCHs (sum of 2 HCHs) and total DDTs (sum of DDTs) in 18 samples detected by GC-ECD ranged from 1.28 ng x L(-1) to 49.2 ng x L(-1) and from 0.42 ng x L(-1) to 12.3 ng x L(-1), respectively. In comparison with those reported for other rivers around the world, the levels of HCHs and DDTs in surface water from Xinxiang ranked middle. The main cause for HCHs and DDTs residues in the studied area was usage of lindane and technical DDTs as revealed by the isomer ratios. The ecological risk evaluation was based on the exposure concentration and available chronic toxicity data of p,p'-DDT, gamma-HCHs and DDD, and the overlapping areas of probability density function and safety threshold methods both showed that the ecological risk of these three OCPs to aquatic organism was in the order of DDD > gamma-HCHs > p,p'-DDT. And the probability of exposure concentration exceeding the 10% value of the toxicity data for DDD. Gamma-HCHs and p,p'-DDT was 10.2%, 5.94%, 0.01%, respectively.