北京郊区地表水质状况及有机氯农药残留特征

Water Quality and Residual Characteristics of Organochlorine Pesticides in Surface Water in the Suburb of Beijing

连续2a采用现场采样与室内分析方法相结合的方法,利用气相色谱仪-ASE萃取技术,测定了北京郊区(延庆、顺义、北河运、昌平、温榆河和房山)地表水有机氯农药(OCPs)残留物组成以及水质指标,并探讨了OCPs与水质(pH,透明度,全N,全P和全C)之间的关系。结果表明:(1)北京郊区地表水中残留有机氯农药种类较多,主要是六六六(HCHs)、滴滴涕(DDTs)和六氯苯(HCB),三者占有机氯农药残留总量的99.40%,其中HCHs占总有机氯农药类OCPs物质的56.01%,是北京郊区地表水残留有机氯农药类的主要成分,其他有机氯农药所占比例较小,总体污染程度较轻。(2)氯丹(TC+CC)、九氯(TN+CN)、硫丹(α-End+β-End)残留量较低,是北京郊区地表水中普遍存在的一类持久性有机污染物,并没有对地表水质量造成危害。(3)温榆河和房山地表水中(DDD+DDE)/DDT>1,属于残留污染,北运河、昌平、顺义地区地表水中(DDD+DDE)/DDT<1,可能有新的污染输入;北京郊区大部分地表水DDTs的转化产物主要是以DDE为主,o,p'-DDT是DDT类污染物的主体物质。(4)北京郊区各地区地表水HCH平均值基本为β-HCH>γ-HCH>α-HCH>δ-HCH,其中α-HCH和β-HCH所占比例相对较高,具有较高的潜在危害性,除了温榆河和房山,其他地区地表水α-HCH/γ-HCH比值均小于1,说明地表水中HCH同系物之间发生相互转化,地表水均有较多的γ-HCH残留。(5)Pearson相关分析表明,TOC与HCHs、HCB、OCPs呈极显著正相关(P<0.01),由此,可以推断北京郊区地表水HCHs、HCB含量在很大程度上受TOC影响,并且地表水中TOC含量在决定OCPs含量上起着重要的作;冗余分析结果显示对北京郊区地表水有机氯农药影响最大的水质因子为水质透明度(其相关系数绝对值为0.798)。

The residual characteristics of organochlorine pesticides（OCPs）in surface water in the suburb of Beijing（Yanqin,Shunyi,Beiyunhe,Changpin,Wenyuhe and Fangshan）and water quality index were measured through the method of accelerated solvent extraction（ASE）in gas chromatography,based on field sampling and laboratory analysis from 2013 to 2014,and the correlations between OCPs and water quality factors（pH,transparency,total nitrogen,total phosphorus and total carbon）were discussed.The results showed that：（1）The residues of various organochlorine pesticides were observed in surface water in the suburb of Beijing,and HCHs,DDTs and HCB were the dominant organochlorine pesticides,accounting for 99.40% of the total OCPs.DDTs was the primary compound in surface water in the suburb of Beijing,accounting for56.01%,while other OCPs had smaller proportions,and the pollution of surface water in Beijing suburb was not serious.（2）The residues of chlordane（TC＋CC）,trichlor（TN＋CN）and endosulfan（α-End＋β-End）were low.These pesticides did not cause pollution of the surface water in Beijing suburb.（3）The ratio of（DDD＋DDE）/DDT was higher than 1in surface water of Wenyuhe and Fangshan,possibly due to the residue pollution,while the ratio of（DDD＋DDE）/DDT was lower than 1in surface water of Beiyunhe,Changpin and Shunyi,which possibly indicated new input of pollutant.However,DDE was the main transformation product of DDTs in surface water in the suburb of Beijing,and oand p＇-DDT were the main DDT pollu-tants.（4）The average content of HCH in the surface water in Beijing suburb followed the sequence ofβ-HCH〉γ-HCH〉α-HCH〉δ-HCH,with higher proportions ofα-HCH andβ-HCH,which had a higher level of potential harmfulness.In the suburb of Beijing except Wenyuhe and Fangshan,the ratio ofα-HCH/γ-HCH was lower than 1,indicating that transformation occurred between HCH homologues and high level ofγ-HCH residue was observed in surface water in the suburb of Beijing.（5）Pearson correlation analysis revealed that HCHs,HCB and OCPs had significant positive correlations with TOC（p〈0.01）,indicating that TOC had important effects on HCHs,HCB and OCPs,as well as the level and distribution of OCPs,in surface water in the suburb of Beijing.Redundancy analysis results showed that the most important water quality factor influencing OCPs in surface water in Beijing suburb was water transparency（absolute value of related coefficient：0.798）.