有毒难降解有机污染物的光催化降解

有毒难降解有机污染物的光催化降解在原理、过程和效率等方面仍然存在着巨大的挑战,特别是光催化剂的构效关系、可见光的利用、分子氧的活化和污染物分子矿化分解的机理仍然是今后的研究热点.本文就近年来在半导体光催化和负载型铁离子光催化降解有毒有机污染物的两个重要方面的研究进展进行了评述.     

水相中POPs光化学降解研究进展

综述了近年来12种持久性有机污染物(POPs)在水体中光化学降解行为,从水体中POPs的光解途径、光解机理和定量结构-性质关系(QSPR)三个方面探讨了POPs在水体中的光化学行为,展望了水体中POPs光化学行为的研究前景.     

大气持久性有机污染物(POPs)被动采样

大气是进行全球和区域持久性有机污染物(persistent organic pollutants,POPs)观测的良好介质.对<斯德哥尔摩公约>履约效力评估的需求,加速了大气POPs采样技术的研发与应用.大气POPs被动采样技术(passive atmospheric sampling,PAS)在近年来得到了飞速发展,日益成为大流量大气采样的重要补充手段,并显示出其在广大区域范围内实现大气POPs同步观测的优势.本文综述了大气PAS技术的基本原理,介绍、评价了几种主要大气PAS装置,重点分析了PUF-PAS的应用技术原理,介绍了大气PAS在全球各区域和不同研究领域的应用研究进展,分析了大气PAS研究领域的动态,提出了今后大气PAS研究中值得关注的研究内容和趋向.     

Isolation of Lipophilic Persistent Organic Pollutants From Human Breast Milk

Background: Lipid removal from biological samples can be achieved by addition of concentrated sulfuric acid. However, certain persistent organic pollutants (POPs) such as chlorophenols are decomposed by sulfuric acid treatment and, thus, a more gentle lipid reduction method is needed for extraction of many environmental contaminants from biological samples. Membrane dialysis extraction (MDE) is a non-disruptive method to extract POPs from biological matrices.

Methods: Human breast milk samples were spiked with radiolabelled p,p′-dichlorodiphenyl trichloroethane ([C-14]-DDT) as a POP proxy and extracted using solid phase extraction (SPE). The extracts obtained were dialyzed by MDE in low-density polyethylene tubings containing a mixture of n-hexane and dichloromethane for 24 h, 48 h, or 72 h.

Results: The lipid content was reduced by 86.2% after one dialysis cycle of 24 h using MDE, and 87.1% recovery of the [C-14]-DDT standard was obtained. The DDT recovery could be further increased up to 96.3% and 98.1% by repeating the dialyses for one or two more cycles, respectively. However, the increased [C-14]-DDT recovery includes a concomitant increase in lipid carryover from 13.8% with one dialysis cycle to 22.1% with three cycles.

Conclusion: An SPE procedure for extracting POPs from breast milk and dialytic conditions for isolation of the extracted POP with minimal lipid carryover was established. The method is nondestructive and acceptable recoveries can be obtained within a single solvent shift as demonstrated by spiking standards. The lipid carryover was minimized, and the method may be considered for lipid removal before HPLC or GC analysis of environmental contaminants.     

Application of a multi-laser tunable diode laser absorption spectrometer for atmospheric trace gas measurements at sub-ppbv levels

We describe the application of a three-laser tunable diode laser absorption spectrometer (TDLAS), called 'tracer in-situ TDLAS for atmospheric research' (TRISTAR), to measure nitrogen dioxide (NO2), formaldehyde (HCHO) and hydrogen peroxide (H2O2), during an intensive measurement campaign on Mt. Cimone (44 degrees 11'N, 10 degrees 42'E, 2165 m asl), Northern Appenines, Italy in June 2000 as part of the EU-project 'mineral dust and tropospheric chemistry' (MINATROC). The TRISTAR instrument was a major component of an instrument package, provided by the Max-Planck-Insitut für Chemie, to investigate free tropospheric gas-phase chemistry over the Appenines. Here we discuss the optical, electronic, gas flow, and calibration setup of the TDLAS used during the campaign. We characterized extensively the instrument's performance during a preparatory phase in the laboratory and compared the laboratory results to the in-field results. Consistency checks with additional trace gas measurements obtained during the campaign create high confidence in the measured concentrations. Correlations between different trace gas species, along with other evaluation tools, allow a full chemical characterization of air masses to meet the goals of the campaign.     

气相色谱-质谱联用测定艾叶中持久性有机污染物

本文建立了气相色谱-质谱(GC-MS)联用测定艾叶中持久性有机污染物的分析方法。样品以正己烷和丙酮为提取剂,经提取液浓H2SO4和硅胶柱净化后,通过GC-MS联用测定19种有机氯农药和多氯联苯残留。结果表明,在25、50、100ng/g添加水平下平均回收率分别为71.0%~93.6%、79.7%~105.9%、85.1%~108.7%,相对标准偏差(RSD)分别为2.4%~11.6%、1.1%~8.6%、0.9%~7.5%。使用该方法分析不同批次的艾叶发现主要残留物为有机氯农药,其次是低氯取代的多氯联苯。方法简便高效,精密度好,可用于艾叶中持久性有机氯污染物的分析。     

有机污染物的持久性评价方法研究进展

持久性有机污染物(POPs)具有持久性、生物蓄积性和高毒性等特点,对人类生存和发展已构成了严重威胁。本文对近年来有关POPs持久性的3种主要量化评价方法的研究进展进行了综述。其中,QSAR/QSPR方法主要以分子结构来推测有机物的理化性质,进而预测总持久性和长距离迁移能力;环境多介质模型方法根据物质在各种环境介质中的分配和反应性来评价物质的持久性;基于化学反应常数的评价方法是通过模拟和简化自然界的各种化学反应,尝试利用测得的反应常数比较物质的持久性。各种方法得到的物质持久性的评价和排序不尽相同,因而仍需要更深入广泛的研究,以建立统一的有机物持久性量化评价的标准体系。     

预富集空气中硫化氢及甲硫醇的固体吸附剂的选择

硫化氢和甲硫醇是挥发性恶臭硫化物(VSCs)中的主要成分,是环境监测的主要物质之一,这类化合物通过自然的和人为的因素释放到大气中,随着工业的发展和人口的剧增,人为因素的硫化物排放愈加显著。近年有关恶臭污染投诉案件不断增加。为确定污染源及污染强度,需对环境中VSCs污染进行监测[1]。但某些空气样品中的VSCs含量较低(ppt~ppb级),常用的火焰光度检测器(FPD)的灵敏度尚达不到要求,需要结合相关的样品预富集技术[2]。常用的有液氧冷阱富集法,此法需要液氧设备,操作和使用不便,对于远距离现场采样后,易造成样品失真。应用固体吸附剂吸…     

气相色谱高分辨质谱测定婴儿胎发中含氯持久性有机污染物

婴儿的胎发是评价婴儿在母体环境中污染物累积暴露水平的良好介质。含氯持久性有机污染物是人体中残留浓度最高的持久性有机污染物。本研究依次采用HCl酸化、正己烷/二氯甲烷混合溶液萃取、硅胶和氧化铝混合填充小柱净化,以及气相色谱高分辨质谱法检测了北京20个婴儿胎发中的16种典型含氯持久性有机污染物。结果表明,16种目标物的检出限可达到1.0~2.5μg/kg,替代物五氯硝基苯回收率大于67.6%,加标样品中目标物回收率范围为62.5%~92.3%。20个胎发样品中六氯苯、β-六六六和p,p’-滴滴伊检出率均为100%,γ-六六六、2,4,4’-三氯联苯和2,2’,5,5’-四氯联苯的检出率分别为85%,50%和40%。4种污染物总量的浓度分布范围分别为5.48~8.40μg/kg(六氯苯)、3.86~27.1μg/kg(六六六)、1.16~18.3μg/kg(滴滴涕)和2.20~22.1μg/kg(多氯联苯),平均浓度分别为6.91,6.10,5.53和3.44μg/kg。此方法和分析结果可用于胎儿体内16种含氯持续性有机污染物蓄积水平和母体内累计暴露水平的评价。     

基于估计均方差的统计量Sp的修正变量选择法用于持久性有机污染物毒性研究

提出并详细说明基于估计均方差的统计量Sp的修正变量选择(MVSSp)方法. 采用分子电性距离矢量(MEDV)及其二次项表征多氯二苯并呋喃(PCDFs), 多氯二苯并二噁英(PCDDs)和多氯联苯(PCBs)三种持久性有机污染物异构体分子结构, 结合MVSSp方法选择适当的描述子, 建立了三种持久性有机污染物分别对芳烃受体(AhR)亲合性, 芳香羟化酶(AHH), 7-乙氧基异吩唑酮-脱乙基酶(EROD)诱导作用的定量结构活性相关(QSAR)模型, 模型的质量优于文献或相当, 讨论了这些实验毒性与分子结构关系. 这对研究和预测这些持久性污染物的毒性具有一定的指导意义.     

广义相关指数用于持久性环境污染物的定量结构-色谱保留关系研究

基于分子拓扑图形特征和顶点连接方式,通过定义广义相关函数、性质相关参数以及距离关系函数等概念,将“面向用户”实际应用的观点及对目标问题“自适应性”的思想引入到分子结构表征当中,从而得到一种新型分子拓扑性质表征方法:广义相关指数(GC I)。使用该指数对115个多氯代二苯并呋喃、41个多氯代二苯并-p-二、62个多氯代萘和210个多氯联苯在DB-5气相色谱柱上的保留行为进行了定量结构-色谱保留关系研究,所得模型复相关系数Rcum以及交叉检验复相关系数Qcum均在0.98以上。结果表明GC I指数具有较强分子结构表达能力及对化合物各类性质的优良适应性。     

Investigation of different types of filters for atmospheric trace elements analysis by three analytical techniques

Different atmospheric aerosol samples were collected on three types of filters. Disks of both loaded and clean areas of each kind of filter were investigated by XRF, PIXE and Scanning Electron Microscope (SEM) methods. The blank concentration values of the elements Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br and Pb in the three types of fiters are discussed. It is found that for trace elemental analysis, the Nuclepore membrane filters are the most suitable for sampling. These have much lower blank element concentration values than the glass fibres and ash free filters. It was found also that the PIXE method is a more reliable analytical technique for atmospheric aerosol particles than the other methods.     

Behaviour of solid adsorbents for the sampling of atmospheric organochlorine compounds

The behaviour of Tenax(R) GC, Polyurethane foam (density 0.022 g/cm(3)), Amberlite(R) XAD-2 and Amberlite(R) XAD-4 alone or in combination has been studied. Standard atmospheres containing different concentration levels of hexachlorocyclohexane and chlorobenzene isomers were generated and trapped in adsorbent cartridges. The generation of the atmosphere, the adsorption by the cartridges, the extraction of the compounds, the evaporation of the final solution and the analysis of GC/ECD have been studied. The most efficient system for trapping the test gases is the use of two cartridges connected in series, one containing Polyurethane foam and the second one containing Tenax GC. Recovery values ranging from 72% for 1,3-dichlorobenzene to 98% for gamma-hexachlorocyclohexane are obtained, most of them >90%. The SD values for all the compounds under study are around 4% for a total sampled amount of 0.5 mug of each compound.     

Multi-residue method for the determination of 57 Persistent Organic Pollutants in human milk and colostrum using a QuEChERS-based extraction procedure

Human breast milk represents the best choice for the nutrition of infants. However, in addition to containing beneficial nutrients and antibodies, it can also be considered the best indicator of infant exposure to contaminants. We developed a multi-residue method using a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure and capillary gas chromatography–triple quadrupole mass spectrometry for the determination of 57 persistent organic pollutants, including 23 organochlorine pesticides, 18 polychlorinated biphenyl (PCB) congeners, and 16 polycyclic aromatic hydrocarbons in human milk and colostrum samples. We have used primary secondary amine in the clean-up step as it gave a more efficient separation of the analytes from fat and superior removal of the co-extracted substances compared with gel permeation chromatography. No significant matrix effect was observed for the tested pollutants, and therefore matrix-matched calibration was not necessary. The average recoveries from spiked samples were in the range of 74.8–113.0 %. The precision was satisfactory, with relative standard deviations below 16 %, while values of 0.1–0.4 μg L^?1 were established as the limit of quantification for all the target analytes (0.05 and 100 μg L^?1). The method was successfully applied to the analysis of 18 human colostrum and 23 mature milk samples. All the samples tested were positive for at least nine different residues, with some samples containing up to 24 contaminants. Remarkably, the contaminants hexachlorobenzene, p,p’-DDE, PCB 138, PCB 180, phenanthrene, fluoranthene, and pyrene were present in 100 % of the colostrum and mature milk samples analyzed.     

Comparison of different types of filters for atmospheric trace element analysis by three analytical methods

Different atmospheric aerosol samples were collected on three types of filters. From both of the loaded and clean areas of each kind of filter, different disks were cut and investigated by XRF, PIXE and scanning electron microscopy (SEM). The blank concentration values of the elements Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br and Pb in the three types of filter are discussed. It is found that for trace elemental analysis, the Nuclepore membrane filters are the most suitable for sampling. These filters have much lower blank element concentrations than the glass fiber and ash free filters. It was found also that PIXE is a more reliable analytical technique for atmospheric aerosol particles than the other methods used.     

Determination of carbohydrazide at trace and subtrace levels

We developed three analytical methods for the determination of carbohydrazide at different concentration levels. One involves the volumetric titration of the analyte with bromate ion and dead-stop end-point detection, and is applicable to concentrations above 10 mg/l., so it can be used for standardizing carbohydrazide solutions. A second, spectrophotometric method is based on the reduction of FE(III) and measurement of the absorbance of the Fe(II)-ferrozine complex, and features an applicability range of 25-700,mug/l. carbohydrazide. The third method uses differential pulse polarography and the oxidation of carbohydrazide in a basic medium at a dropping mercury electrode to determine the analyte. This last method is the most sensitive of the three and also that offering the widest determination range: from 4 to 3000 mug/l. carbohydrazide.     

Determination of the trace element levels in atmospheric pollutants by neutron activation analysis

An investigation of the potentials of neutron activation analysis for the routine analysis of trace elements present in atmospheric pollutants is discussed. Various techniques including sequential air sampling, multiple neutron irradiation, high resolution γ-ray spectrometry, chemical isolation, high flux neutron irradiation and X-ray spectrometry have been employed to determine the levels of Pb, Al, V, I, Cl, Mn, Cu, Br, Na, La, Mo, Au, Cr, Fe, Ni, Se, Zn, Ag and Co in atmospheric pollutants. The results of the analysis of nearly two hundred samples collected from the Buffalo New York area during 1968–1969 are reported. Presented at the Fourth Annual Conference on Trace Substances in Environmental Health, University of Missouri, Columbia Missouri, USA (June, 1970).     

气相色谱/质谱-选择离子检测法同时测定大米中的25种持久性有机污染物

利用超声波提取、固相萃取净化对样品进行前处理,然后采用气相色谱/质谱-选择离子检测模式对大米中的25种持久性有机污染物进行了分析。色谱条件:DB-35MS毛细管色谱柱(30 m×0.25 mm i.d.×0.25 μm);载气为氦气,流速1 mL/min;进样口温度300 ℃;不分流进样,进样量1 μL;柱温为程序升温模式。质谱条件:电子轰击电离源,70 eV;采集方式为选择离子方式,扫描质量范围50~450 u。实验采用保留时间以及定性、定量特征离子的丰度比定性,采用峰面积外标法定量,制作了25种持久性有机污染物的标准工作曲线。不同浓度水平的添加回收率试验表明,25种持久性有机污染物的添加回收率为81.99%～100.60%,相对标准偏差为2.37%～18.48%,除异狄氏剂、反式氯丹和顺式氯丹的检测限分别为20,30和20 ng/g外,其他有机污染物的检测限为0.1～5 ng/g。该方法的灵敏度、准确度和精密度均符合农药多残留测定技术的要求。     

生活饮用水中挥发性有害有机污染物分析及其安全性评价

生活饮用水安全性是与人们身体健康休戚相关的问题,除了微生物和重金属外,饮用水中有害有机污染物的存在情况也日益受到人们的关注。从1974年发现氯消毒会产生具有致突变和致癌症的三氯甲烷以来,国际饮用水界研究消毒副产物的工作就没有停止过。大量流行病学研究证明长期饮用氯消毒的水会增加人们得癌症的危险。为此,世界各国和地区都制定了生活饮用水水质标准及规范,以保证人们生活饮用水的安全性。美国《国家饮用水基本规则》对92种污染物做出了硬性规定,世界卫生组织(WHO)则有133项,其中有机物占89项,欧共体有61项,我国卫生部2001年颁布的生活饮用水卫生规范有96项,其中常规检验指标有34项,增加了一些消毒副产物的规定,虽然大部分为非常规项目,但有了相关限定值。本文对有代表性的几种生活饮用水中挥发性有机物进行了分析测定。     

一种新的有机污染物采样装置

介绍了一种由类脂物和半透膜组成的采样装置,该装置可模拟生物监测可被生物订的有机污染物。将其用于监测大气、水体、沉积物中的多氯联苯（ＰＣＢｓ）、有机氯农药（ＯＣＰ）和多环芳烃（ＰＡＨｓ）时,结果满意。