桂林会仙岩溶湿地水体与沉积物中有机氯农药污染特征

Pollution Characteristics of Organochlorine Pesticides in Water and Sediments of Huixian Karst Wetland in Guilin

湿地对环境污染起重要的缓冲作用,但岩溶区岩溶管道的存在会导致污染物沿高度发达的岩溶管道对地下环境产生威胁.因此,认识岩溶地貌环境中的污染物分布特征是污染物生态风险评估与防范的前提.以24种有机氯农药(OCPs)为研究对象,分析了桂林会仙湿地枯水期和丰水期水体和表层沉积物中OCPs的含量组成特征,解析其来源,并开展风险评价.结果表明,水体中ρ(OCPs)范围为3.17~92.50 ng·L^(-1),沉积物中ω(OCPs)范围为1.16~219.52 ng·g^(-1),呈现以六六六(HCHs)和滴滴涕(DDTs)为主的污染特征,水中OCPs含量表现为丰水期高于枯水期,沉积物中OCPs含量枯水期高于丰水期.特征比值法表明OCPs主要为长时间降解残留,部分点位有林丹的新输入.基于蒙特卡洛模拟开展健康风险评价,结果表明,95%分位数水平上,水体中OCPs对人体致癌风险大于1×10^(-6),存在潜在健康风险但可接受;非致癌风险均低于1,说明研究区水体中OCPs残留水平不足以对人体造成非致癌风险.

Karst wetland plays an important role in the ecological environment;however,due to the existence of karst pipeline,pollutants can threaten the underground environment through the highly developed karst pipeline.Therefore,understanding the pollution characteristics of the karst surface environment is the premise of pollution ecological risk assessment and prevention.In this study,24 organochlorine pesticides(OCPs)were analyzed to study the concentration,composition,source,and risk of OCPs in water and surface sediments in the Huixian Wetland of Guilin.The results showed that:the concentration of OCPs in water ranged from 3.17 ng·L^(-1)to 92.50 ng·L^(-1),and the concentration of OCPs in sediment ranged from 1.16 ng·g^(-1)to 219.52 ng·g^(-1),showing the main pollution characteristics of HCHs and DDTs.The concentration of OCPs in water was higher in the wet season than that in the dry season.The concentration of OCPs in sediments was higher in the dry season than that in the wet season.The isomer ratios revealed that OCPs in the study area were mainly derived from long-term degradation residues,and some sites had new input of lindane.Based on Monte Carlo simulation,the human health risk assessment of the study area showed that the 95%quantile carcinogenic risk of OCPs in water was greater than 1×10^(-6),with potential but acceptable health risk.The non-carcinogenic risk was lower than 1,which indicated that the level of OCPs residues in the water in the study area was not enough to cause non-carcinogenic risk to the human body.