某人工湿地系统对水中持久性有机污染物去除效果的分析

Study on constructed wetland efficiency for removing persistent organic pollutants

采用固相萃取样品前处理技术和气相色谱/电子捕获检测器(GC/ECD)及气相色谱/质联联用(GC/MS)分析方法,对某人工湿地系统进、出水中持久性有机污染物(包括多环芳烃、多氯联苯、有机氯农药)的质量浓度进行了分析和对比,以研究该湿地水中持久性有机物的污染水平及湿地对它们的处理效果。结果表明,多环芳烃检出19种,以二环为主,萘及其同系物约占总量的71%;有机氯农药只检出HCH的4种异构体和七氯;多氯联苯检出5种,以二氯代为主。这3类物质的浓度水平明显低于以往的研究结果,且低于国家地表水环境质量标准(GB3838—2002)。对于持久性有机物浓度较低的水源水,湿地对以上3类物质的去除效果不明显。

This paper is intended to report the authors＇ research on a new water treatment technology for removing the persistent organic pollutants. Literally, the treatment technology is known as the artificially cultivated marshland system to be used for in-taking and outletting water moisture so as to remove the persistent organic pollutants. In doing so, we have studied and compared the concentrations of polycyclic aromatic hydrocarbons （ PAHs ）, organochlorine pesticides（OCPs） and the polyehlorinated biphenyls （PCBs） . The pollutants can be enriched by the solid phase extraction and analyzed by the GC/ECD and GC/MS. As a result of study, it can be concluded： First of all, the total concentration of the persistent organic pollutants should not go beyond the relative limits of surface water environment quality standards （GB 3838--2002 ） and the water supply standard （CJ/T 206--2005） in China. And, secondly, as compared with the former reported results, the current concentration of PAHs, OCPs and PCBs remains much lower. Among the 19 PAHs detected in the water area under study, most of them are Dicyclic Aromatic Hydrocarbons, with naphthalene and its homologues being as high as 71%. With the concentration of benzo（a）pyrene being 10 ng/L, the reported results of 2001 stand for 1.13 - 3.04 μg/L. At the same time, among the 12 OCPs detected in the former water areas, the total concentration of HCHs is 53.5 ng/L with only 4 HCH isomers and heptachlor detected and the total concentration of HCHs being 8.32 ng/L in the current water area. The other results concerned are： the concentrations of lindane in inlet and outlet water are 2.56 ng/L and 2.96 ng/L. Among the 12 kinds of PCBs, most of them are pentachlorinated and hexachlorinated with Biphenyls detected in the sediments in 2001. However, only 5 kinds PCBs, most of which are dichlorinated Biphenyls, are detected in the current waters. Thirdly, the suggested acultivated marshland can help to prevent the 3 kinds of persistent organic pollutants successfully for two reasons ： （ 1 ） the concentrations of the 3 kinds pollutants are comparatively low and influenced by the sediments; （2） the water＇ s residence time is only 34 h while the degradation of persistent organic pollutants needs much more time.