表面活性剂冲洗修复多氯联苯污染土壤多相流研究

多氯联苯(PCBs)是一种具有持久性、抗生物降解性、脂肪溶性和明显的生物毒性等特性的持久性有机污染物,PCBs在土壤中难于准确定位、难被分解和强烈吸附,去除土壤中PCBs比较困难.表面活性剂冲洗法可以通过提高PCBs溶解度和降低水-PCBs界面张力来实现PCBs从土壤中去除;表面活性剂冲洗PCBs污染土壤涉及气相、水相、NAPLs相和固相等物质,是多相共存并相互发生作用的过程,发生相对渗透率、饱和度和毛细压力的变化;另外,为研究表面活性剂冲洗土壤中PCBs的去除机理,并降低PCBs对研究人员的危害,采用微观孔隙结构网络模型是一种较新颖的和效果显著的研究方法.开展表面活性剂冲洗PCBs污染土壤多相流研究,可以为PCBs污染场地修复提供理论基础和实验支持,并促进我国POPs履约工作的顺利进行.     

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

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(GB 3838-2002).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.     

Polychlorinated Biphenyls (PCBs) in Mussels along the Chilean Coast

- DOI: http://dx.doi.org/10.1065/espr2006.01.011 Goal, Scope and Background Chile signed the Stockholm Convention, which establishes measures to reduce or eliminate Persistent Organic Pollutants (POPs) release into the environment, including the prohibition of their use and reduction of secondary products release, as well as management related with waste treatment. Among POPs, PCBs are a family of 209 compounds that differ in chlorine level and position. These substances present a wide variability in their physicochemical properties such as vapor pressure, water solubility and partition coefficients that determine their behavior and mobility within the different environmental compartments. In Chile, as in other countries, the use of these compounds were and continue to occur in diverse industrial applications such as dielectric fluid in transformers and condensers, with a use in Chile of approximately 550,000 L. A sampling of bivalves was performed during the years 2000-2002 in order to obtain information on the spatial distribution of the PCB levels for the length of the long Chilean coast (180–540 South latitude, 4,200 km), contributing in this way to a better understanding of the PCB trend and eventual fractionation along latitudinal gradients in Chile, using as the bivalve Perumytilus purpuratus ('Chorito Maico') bioindicator. Methods The marine bivalves Perumytilus purpuratus were collected in 16 localities in northern and southern Chile. All samples were lyophilized, and PCBs (51 congeners) were extracted in a Soxhlet system (24 h) with n-hexane. Samples were cleaned in florisil and analyzed by GC-ECD. Blanks, certified reference materials and standards were processed along with the samples. Results and Discussion The results obtained for P. purpuratus indicate a congeneric distribution profile associated to a latitudinal gradient, and the statistical analysis of the congeneric composition of the PCBs indicated five groups in relation to the molecular weight (number of chlorines), where the lighter congeners were observed in areas corresponding to high latitudes with total PCB values of 298 ng/g dry weight. Conclusion P. purpuratus turns out to be a good bioindicator of PCB levels in the coastal areas of Chile due to its wide distribution. The highest concentrations and the more volatile congeners were found in southern Chile, which could be the result of processes of long-range transport or illegal discharge occurring in such remote areas. These results confirm previous data from the International Mussel Watch project ten years ago. Recommendation and Outlook Future studies are needed to confirm our findings utilizing another environmental matrix such as soil/sediments and air samples.     

分子电性距离矢量预测多氯萘的正辛醇/空气分配系数

应用分子电性距离矢量(MEDV)对多氯萘(PCNs)的76种同系物进行结构表征,通过多元线性回归方法建立了PCNs的正辛醇/空气分配系数(lgKoA)与MEDV之间的定量结构一性质关系(QSPR),该模型具有显著的相关性(n=24,R=0.997,SD=0.088,F=417.546).采用逐步回归的方法(SMR)从原...     

珠三角电子垃圾和城市地区家庭灰尘中多氯联苯的来源及暴露风险

本研究对珠三角电子垃圾和城市地区家庭灰尘中多氯联苯(PCBs)进行了分析.结果表明,清远电子垃圾区灰尘中PCBs的含量为12.4～87765 ng·g-1,平均10167 ng·g-1.室内和庭院灰尘中PCBs的含量无显著差别.电子垃圾区灰尘中PCBs组成模式(以3、5、6、4氯代PCBs为主),与我国工业品中PCBs的组成并不相似,并且室内外灰尘中的组成没有明显的差别.采用化学质量平衡受体模型进行源解析显示,电子垃圾区灰尘中PCBs主要来自Aroclor 1262(36.7%)、Aroclor 1254(26.7%)、Aroclor 1242(21.4%)和Aroclor 1248(18.5%).电子垃圾区婴幼儿、儿童/青少年、成人通过灰尘对PCBs的平均日暴露量分别为42、17和2.9 ng·(kg·d)-1.风险评估显示,婴幼儿、儿童和青少年通过灰尘暴露PCBs的总非癌症危害商数(HQ)均高于1,可对身体健康产生危害,人群终生平均致癌风险为4.5×10-5,处于美国EPA可接受的致癌风险范围.广州地区家庭灰尘中PCBs的平均含量仅为48.7 ng·g-1,这与PCBs并未在我国大范围使用一致.广州地区人群通过家庭灰尘暴露PCBs的风险很低.     

过硫酸盐对电动-铁/碳复合材料联合修复多氯联苯污染土壤的强化作用

研究了3种浓度过硫酸盐溶液(2、20和200 g·L^-1,以下分别表示为0.2%、2%、20%)作为电解液对电动-铁/碳复合材料（EK-Fe/C）联合修复多氯联苯（PCBs）污染土壤的强化作用,并探究了EK-Fe/C-PS修复技术对土壤理化性质的影响.结果表明,EK-Fe/C-PS修复7 d后,土壤温度和可溶性有机质含量增加,p H显著降低,电导率下降.PS对EK-Fe/C联合修复PCB28污染土壤具有显著的强化作用,修复效果整体随PS浓度增加而增加.在PS浓度为20%时,PCB28的7 d平均去除效率最高（60.9%）,是EK-Fe/C处理组（20.5%）的3倍,EK-20%PS处理组（32.0%）的近2倍.阳极侧土壤PCB28去除效率显著高于阴极侧,达到92.7%±7.7%.在两个电极中间区域,PS浓度增加对修复效果的影响不显著.为降低修复成本和对土壤的影响,污染土壤修复实践中可先使用高浓度PS快速修复阳极和阴极侧土壤,再使用低浓度PS强化修复中间区域土壤.     

The Distribution and Impacts of Dioxins and Polychlorinated Biphenyls in the Taiwan Er-Jen River

The distribution and impacts of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs) and polychlorinated biphenyls (PCBs) in the Taiwan Er-Jen River were investigated by monitoring fish distribution and measuring PCDD/DFs and PCBs levels in sediment and fish samples. Most of the fish collected are pollution-resistant species such as Oreochromis spp, Liza macrolepsis, Channa spp and Megalops cyprinoides. the most polluted river sections are in the upstream where large amount of waste effluents from households, livestock rearing and nearby dumping sites were discharged into the river, and the lower reaches of the river where metal recovery activities including open burning of waste electrical wire/scrap occurred. Sediment samples collected near the burning site show 2,3,7,8-TCDD toxicity equivalents (TEQ) ranging from 0.014 to 14.2 ng g^-1 by PCDD/DFs and from 0.015 to 1.03 ng g^-1 by coplanar PCBs (Co-PCBs). the fish samples show TEQ ranging from 0.029 to 0.615 ng g^-1 by PCDD/DFs and from 0.012 to 0.12 ng g^-1 by Co-PCBs. Possible PCDD/DFs sources are discharged PCBs, open burning of waste wire/scrap, and pentachlorophenol. the consumption of these fish will cause an average intake of 54 pg kg^-1 d^-1 TEQ. the prevention of direct discharge of livestock and the dumping of waste effuents into River Er-Jen as well as the control of metal recovery activities appears to be the first step toward the restoration of River Er-Jen.     

北京市火葬场大气污染物排放现状及污染特征

遗体火化和祭品焚烧过程会产生烟尘、CO、SO2、NOx等常规大气污染物及Hg、PCDD/Fs等有毒有害物质,且由于排放高度较低,对周边空气质量及人体健康造成影响,引起越来越多的关注.本研究通过实地调研和资料收集,获取相关的活动水平;选择典型火化机进行污染物排放的实际监测,了解当前北京市火化机大气污染物排放水平;采用排放因子法核算了2012年北京市火葬场大气污染物排放量,并定量了其不确定性范围.利用大气扩散模型,评估火葬场对周边环境的影响,识别其大气污染特征.结果表明,北京市安装烟气净化系统的火化机烟尘排放浓度较低,CO排放浓度波动较大,火化机燃烧控制欠佳,导致PCDD/Fs排放浓度相对较高;北京市火葬场遗体火化产生的烟尘、CO、SO2、NOx、Hg和PCDD/Fs分别为11.5t、41.25 t、2.34 t、7.65 t、13.76 kg和0.88 g;根据模拟计算结果,12家火葬场对北京市整体环境空气质量影响较小,但对周边环境会产生一定的影响,烟尘、CO、SO2、NOx、Hg、PCDD/Fs最大浓度贡献为0.059 47μg·m-3、0.200 9μg·m-3、0.012 6μg·m-3、0.036 67μg·m-3、0.062 47 pg·m-3、0.004 213 pg·m-3.     

城市雨水和土壤中持久性有机污染物分析

为分析城市环境中持久性有机污染物状况,以西安市城区为研究对象,按照城市布局设置10个代表性采样点,分别采集初期雨水和地表土壤样品,采用气相色谱法(GC)测定样品中有机氯农药和多氯联苯两大类持久性有机污染物的含量.结果表明:西安城区雨水、土壤中均含有持久性有机污染物,雨水中以pp'-DDT、α-六六六、pp'-DDD、PCB169、PCB189、PCB126居多,土壤中以op'-DDT、α-六六六、pp'-DDT、PCB169、PCB189、PCB77居多;无论雨水还是土壤中,都是有机氯农药含量高于多氯联苯含量;雨水中pp'-DDT、多氯联苯PCB169平均质量浓度分别超过GB 3838-2002《地表水环境质量标准》限值的12倍、100倍,土壤中的六六六和DDT质量比尚未超过GB 15618-1995《土壤环境质量标准》一级标准.有机氯农药和多氯联苯的逸度商(fa/fa)均远小于1,西安城区POPs的迁移总趋势是由雨水向土壤表层聚集,降雨会将大气中的POPs通过淋洗等作用带到土壤表层,大气为污染物的源,土壤为其最终的汇集地.     

Occurrence of pesticides and polychlorinated biphenyls in water of the Nile river at the estuaries of Rosetta and Damiatta branches,north of delta,Egypt

Abstract

A study was conducted from summer 1995 to summer 1997 to assess the seasonal occurrence of pesticide residues and other organic contaminants, polychlorinated biphenyls (PCBs), in water at the estuaries of Rosetta and Damiatta branches of the Nile river. The results indicated that organochlorine compounds (OCs) including HCB, lindane, p,p‘‐DDE, p,p‘DDD, p,p‘‐DDT, aroclor 1254 and aroclor 1260 were present in all the water samples at concentration levels ranging between 0.195–0.240, 0.286–0.352, 0.035–0.067, 0.019–0.033, 0.024–0.031, 0.390–0.70 and 0.166–0.330 μg/l, respectively. The levels of these compounds were higher in water of Damiatta branch than those found in water of Rosetta branch. Aldrin, dieldrin and endrin were not detected in all water samples. Only 4 compounds from 36 organophosphorus insecticides, fungicides and s‐triazine herbicides tested were detected in water samples collected during summer and autumn seasons from Rosetta branch. The concentration levels of these detected compounds, dimethoate, malathion, captan, and ametryne, ranged from 0.011 to 0.340 μg/l, respectively. Similar compounds during the same seasons as found in water of Rosetta branch were also detected in water of Damiatta branch except ametryne. The levels of the detected compounds (dimethoate, malathion and captan) ranged between 0.030 and 0.330 μg/l. The levels of detected organophosphorus insecticides, fungicides and s‐triazine herbicides were in the order: dimethoate > malathion > captan > ametryne.