西溪湿地底泥中有机氯农药分布特征及风险评价

Residues and risk evaluation of organochlorine pesticides in sediments of Xixi Wetland in Hangzhou

以西溪湿地为主要研究区域,采集了西溪湿地主要河口的表层和柱状底泥样品,以气相色谱(GC)/电子捕获检测器(ECD)定量测定样品中滴滴涕(DDTs)、六六六(HCHs)的含量,并对其进行生态风险评价。结果表明:(1)西溪湿地底泥样品中DDTs浓度明显比HCHs高。有机氯农药(OCPs)在研究区域内的底泥表层样品中残留呈现不均衡分布的特征,主要是受到河流交汇及人为因素的影响。(2)HCHs和DDTs在不同深度处出现浓度峰值,这与研究范围内的农药使用状况有关,也可能是由于水动力作用及生物扰动等。(3)OCPs与总有机碳(TOC)具有显著的相关性。(4)OCPs的残留主要是历史原因造成的,但DDT(主要包括o,p’-DDT和p,p’-DDT)可能存在新的污染源输入。(5)西溪湿地内DDTs可能存在一定的生态风险,可能对地栖生物产生潜在危害,并造成潜在的负面影响,可以进行进一步的调查研究,明确风险发生的可能性。

The concentration of organochlorine pesticides（OCPs）,such as HCHs and DDTs,in sediments of Xixi Wetland in Hangzhou was analyzed by GC/ECD.Distribution characteristics and biological risk evaluation of OCPs were also investigated.Vertical distribution of OCPs in column sediments was discussed.Results showed that in sediment of Xixi Wetland,the concentration of DDTs was higher than HCHs.Because of river confluence and artificial factors,OCPs in surface sediments of study area presented the characters of unbalance distribution.The peak value of HCHs and DDTs appeared at different depth of sediments,which depend on the application of OCPs or hydrodynamic inducement and bioturbation.Concentrations of OCPs and total organic carbon（TOC） showed a positive correlation in the sediments.The OCPs residue in sediment was caused by the historical reasons,while DDT had the new input source.According to the risk evaluation,OCPs in the surface sediments of Xixi Wetland would cause adverse effect to benthos,further research should be taken to make clear the possibility.