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。     

测定饮用水中总有机碳新方法的研究

为了更准确地分析饮用水体中有机物的污染程度,采用燃烧氧化―非分散红外吸收法中直接法和差减法相结合的新方法测定饮用水中总有机碳(TOC),对单独使用直接法或差减法进行了优化。通过实验确定了该方法的检出限为0.12 mg/L,相对标准偏差为0.62%～1.97%,加标回收率为94%～102%,可用于测定饮用水中的总有机碳。     

示差红外光谱在土壤有机质组成研究中的应用

采用红外透射光谱法,对不同管理方式下黑土有机质组成进行了红外光谱分析,并运用差谱的方法,降低土壤矿物对有机吸收峰的干扰。选择2920、2850、1630和1420 cm~(-1)作为代表有机质官能团的吸收峰,通过积分计算各吸收峰的相对面积,并对吸收峰面积与土壤有机质(SOM)的组分含量进行了相关分析。土壤在2920 cm~(-1)处脂族结构的吸收峰面积与土壤活性有机碳(水溶性有机碳、热水溶性有机碳、游离态轻组碳和闭蓄态轻组碳)含量呈正相关,可反映土壤活性有机碳含量;在1630 cm~(-1)处芳香结构的吸收峰面积与以上活性有机碳含量呈负相关,可反映土壤稳定性有机碳含量。土壤在1630和2920 cm~(-1)处吸收峰面积的比值(1630∶2920)与稳定性(重组)有机碳和活性(轻组)有机碳含量的比值呈显著正相关,可指示SOM的稳定程度。本方法所需样品量少、成本低、便捷,适用于对矿物组成一致的土壤进行有机质组成的测定。     

广州大气细粒子中有机碳、元素碳和水溶性有机碳的分布特征

在广州市中山大学采样点进行了为期1年的大气细粒子(PM2.5)采样,监测分析得到PM2.5及有机碳(OC)、元素碳(EC)和水溶性有机碳(WSOC)等组分的质量浓度,并进行了比较和评价分析。结果表明广州市细粒子碳污染较严重。对OC、EC和WSOC质量浓度的月变化和季节变化特征进行了讨论,并分析了原因。OC、EC浓度相关性好,表明OC、EC来源大部分相同。根据OC/EC比值,估算二次有机碳(SOC)量,结果是SOC占OC的1/3。讨论了SOC和SOC/OC比值的季节分布,结果证明SOC夏季生成比冬季多。     

岩溶地下水中溶解性有机碳测定方法的探讨

总有机碳(TOC)是以碳的含量来表示环境水体中有机物总量的综合指标,是反映水体受污染程度的重要指标。溶解性有机碳(DOC)是总有机碳的一种,通常定义为通过一定孔径(0.22～0.7μm)的滤膜后,水质中所含有机碳的含量[1]。水体中DOC的存在形式主要有溶解态、胶体态和少量较小     

基于介孔碳的电化学酪氨酸酶生物传感器法测定水体中的苯酚及高效液相色谱法评价

采用新型的介孔碳材料作为固载酪氨酸酶的检测平台构建生物传感器,应用于水体环境中苯酚污染物的检测,并通过高效液相色谱法对电化学酪氨酸酶生物传感器法的准确性进行了评价。研究表明,介孔碳的"空间限制效应"能够防止酪氨酸酶(三维尺寸为6.5 nm×9.8 nm×5.5 nm)体外去折叠失活。基于介孔碳材料构建的电化学酪氨酸酶生物传感器在苯酚污染物检测方面显示了优良的性能,其重现性、灵敏度、稳定性、选择性以及检出限均比较令人满意。基于介孔碳的电化学酪氨酸酶生物传感器对苯酚污染物的检出限达到20 nmol/L,线性范围为0.1~10 μmol/L。采用基于介孔碳的电化学酪氨酸酶生物传感器和高效液相色谱法对实际水样品进行测定结果比对,结果表明该生物传感器方法检测结果准确、有效,适合于苯酚污染物突发污染事件的应急检测。     

湿法氧化法测定水中总有机碳

饮用水水质尤其是有机污染物控制问题已成为当今世界普遍关注的问题。目前在水环境监测中常采用化学需氧量(CODCr)、五日生化需氧量(BOD5)、高锰酸盐指数(CODMn)和总有机碳(TOC)等综合指标来表示水中有机物。由于TOC表征不同的碳化合物和氧化状态物,对各种有机物的氧化效率也高,与CODCr、BOD5和CODMn相比较,更能准确、直接、全面地反映水体中总有机物的含量[1,2]。因此,TOC测定越来越受到人们的关注[3,4]。测定TOC的方法很多,传统分析方法有高温催化氧化、辅助湿法氧化等;新颖的分析方法有电阻法、电导法、非分散红外吸收法、…     

碳点的性质及其在化学发光分析中的研究进展

碳点是一种新型的荧光碳纳米颗粒,与传统的半导体量子点相比,碳点具有毒性低、生物相容性好、原料丰富廉价、光稳定性好等特点,得到引了化学、材料和生物等各领域科学家的高度关注。 本文介绍了碳点的基本概念和性质、探讨了碳点在化学发光领域的应用研究进展并进行了展望。     

有机膨润土吸附水中重金属和有机污染物的性能及机理研究

螯合剂柱撑有机膨润土IMB-TMA-Am能有效吸附水中有机物对硝基苯酚(PNP)和重金属离子Cu2 ,其中IMB为内蒙膨润土;CTMA为溴化十六烷基三甲基季铵盐阳离子;Am分别为有机螯合剂乙二胺(En)、三乙烯四胺(TETA)和四乙烯五胺(TEPA)。实验结果表明:螯合剂柱撑有机膨润土对有机污染物的吸附主要表现为有机物在长碳链疏水介质中的分配,其吸附能力和膨润土内有机碳、氮含量一致;对水中重金属离子的吸附机理是Cu2 和进入膨润土层间的有机螫合剂Am形成了配合物,其吸附能力和所形成配合物的稳定性一致。     

生物质铁盐催化加氢热解产生生物油与气态烃的研究

利用加压固定床反应器进行了松木催化加氢热解实验(终温600-700℃、氢压5.0 MPa),考察了硝酸铁和硫酸亚铁两种铁盐对热解产物产率及分布的影响。研究发现,Fe(NO_3)_3能够显著促进生物炭加氢生成甲烷,碳转化率高达97.4%,CH_4产率达21.2%,无水生物油产率为32.8%(产率基准均为干燥无灰生物质),生物油中含氧量降低,轻质芳烃产率增加,其中,苯、甲苯和二甲苯(BTX)产率为2.6%。而FeSO_4迥异于Fe(NO_3)_3,具有抑制气态烃和生物油生成的作用。机理研究表明,Fe(NO_3)_3在加氢过程中主要形成α-Fe,并促使生物炭形成无定型和多孔结构,从而有利于其加氢生成甲烷,而FeSO_4则部分转化为Fe_2S_3,由此可致使铁催化剂失活。     

Effect of a contaminated site (the San Giuliano landfill, Venice, Italy) on the interaction between water bodies in a coastal aquifer system

A complex multiple aquifer system affected by a contaminated site and exposed to tidal effects was investigated to develop the hydrogeological conceptual model of the study case. Two water bodies were identified, from top to down: a surface aquifer unaffected by tidal events, and a semiconfined aquifer partly communicating with the brackish lagoon waters. By using the Cl(-)/SO4(2-) ratio and the DOC (Dissolved Organic Carbon) concentration, as well as by applying the kriking to the piezometric levels results, the groundwater flow directions and the hydraulic gradients within the investigated aquifers were also identified. Based on the overall results, a schematic of the conceptual model for the whole aquifer system was provided which allows to visualize the communication between the different water bodies.     

Natural organic matter removal by coagulation during drinking water treatment: A review

Natural organic matter (NOM) is found in all surface, ground and soil waters. An increase in the amount of NOM has been observed over the past 10-20 years in raw water supplies in several areas, which has a significant effect on drinking water treatment. The presence of NOM causes many problems in drinking water and drinking water treatment processes, including (i) negative effect on water quality by causing colour, taste and odor problems, (ii) increased coagulant and disinfectant doses (which in turn results in increased sludge volumes and production of harmful disinfection by-products), (iii) promoted biological growth in distribution system, and (iv) increased levels of complexed heavy metals and adsorbed organic pollutants. NOM can be removed from drinking water by several treatment options, of which the most common and economically feasible processes are considered to be coagulation and flocculation followed by sedimentation/flotation and sand filtration. Most of the NOM can be removed by coagulation, although, the hydrophobic fraction and high molar mass compounds of NOM are removed more efficiently than hydrophilic fraction and the low molar mass compounds. Thus, enhanced and/or optimized coagulation, as well as new process alternatives for the better removal of NOM by coagulation process has been suggested. In the present work, an overview of the recent research dealing with coagulation and flocculation in the removal of NOM from drinking water is presented.     

Photodegradation of a herbicide derivative, 2,4-dichlorophenoxy acetic acid in aqueous suspensions of titanium dioxide

The photocatalytic degradation of a herbicide derivative, 2,4-dichlorophenoxy acetic acid (2,4-D, 1), has been investigated in aqueous suspensions of titanium dioxide. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic analysis and decrease in Total Organic Carbon (TOC) content as a function of irradiation time in the presence of UV light source. The degradation kinetics was investigated under a variety of conditions, such as different types of TiO₂, pH, catalyst and substrate concentrations. Higher photonic efficiencies were observed with Degussa P25 as compared with other photocatalysts. The degradation products were analysed by GC-MS and probable pathways for the formation of different products were proposed.     

Stability of LaNiO3 gas diffusion oxygen electrodes

In this work LaNiO₃ perovskite-type oxide, prepared by a self-combustion method, was optimized for activity and stability as an anode material for water electrolysis. A full electrochemical study was conducted in order to kinetically characterize electrodes prepared using carbon paper as a base for porous gas-diffusion electrodes in alkaline media, regarding water oxidation and oxygen reduction reactions at room temperature. An electrode stability study was performed by potential cycling and at constant current density, using cyclic voltammetry and electrochemical impedance spectroscopy to check on stability after cycling with complementary scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) analysis of fresh and degraded electrodes. Comparison was made using nickel foam as a support for LaNiO₃ deposition. Carbon instability in the potential region of interest contrasted with the lower contact resistance between the oxide and support of the Ni foam. Higher metal oxide loadings and dimensional stability were also possible.     

Development,validation, and application of a novel LC-MS/MS trace analysis method for the simultaneous quantification of seven iodinated X-ray contrast media and three artificial sweeteners in surface,ground, and drinking water

A new method for the simultaneous determination of iodated X-ray contrast media (ICM) and artificial sweeteners (AS) by liquid chromatography-tandem mass spectrometry (LC-MS/MS) operated in positive and negative ionization switching mode was developed. The method was validated for surface, ground, and drinking water samples. In order to gain higher sensitivities, a 10-fold sample enrichment step using a Genevac EZ-2 plus centrifugal vacuum evaporator that provided excellent recoveries (90?±?6 %) was selected for sample preparation. Limits of quantification below 10 ng/L were obtained for all compounds. Furthermore, sample preparation recoveries and matrix effects were investigated thoroughly for all matrix types. Considerable matrix effects were observed in surface water and could be compensated by the use of four stable isotope-labeled internal standards. Due to their persistence, fractions of diatrizoic acid, iopamidol, and acesulfame could pass the whole drinking water production process and were observed also in drinking water. To monitor the fate and occurrence of these compounds, the validated method was applied to samples from different stages of the drinking water production process of the Industrial Works of Basel (IWB). Diatrizoic acid was found as the most persistent compound which was eliminated by just 40 % during the whole drinking water treatment process, followed by iopamidol (80 % elimination) and acesulfame (85 % elimination). All other compounds were completely restrained and/or degraded by the soil and thus were not detected in groundwater. Additionally, a direct injection method without sample preparation achieving 3–20 ng/L limits of quantification was compared to the developed method.     

Residue study of doxycycline and 4-epidoxycycline in pigs medicated via-drinking water.

A study was performed to determine the residues in edible tissues of healthy pigs after continuous administration of doxycycline with drinking water for five consecutive days at a dose rate of 10.5 mg doxycycline kg-1 body weight (BW) per day. Quantitation was performed using a validated HPLC method with fluorescence detection. The method was able to separate doxycycline and its 4-epimer, 4-epidoxycycline. This epimer was found in kidney, liver, skin, fat and muscle tissue. The method was validated at the maximum residue limit (MRL), at half the MRL and at double the MRL for both doxycycline and 4-epidoxycycline. Linear calibration curves were obtained in spiked tissues (r > 0.99). The accuracy of the calibrators of the calibration curves was within -20% to +10%. The accuracy and precision (expressed as the within-run repeatability) were found to be within the required ranges for the specific concentration. The limits of detection and limits of quantification were below one-half of the MRL. The quantification limits were 50 micrograms kg-1 for doxycycline and 100 micrograms kg-1 for 4-epidoxycycline in kidney and liver, 20 micrograms kg-1 for doxycycline and 50 micrograms kg-1 for 4-epidoxycycline in skin and fat and 10 micrograms kg-1 for doxycycline and 50 micrograms kg-1 for 4-epidoxycycline in muscle tissue. The withdrawal time was calculated according to the recommendations of the European Agency for the Evaluation of Medicinal Products (EMEA/CVMP/036/95) and was set at 3 days. The plasma concentration of doxycycline and the stability of doxycycline in drinking water were also determined during the treatment period. The mean plasma concentration of doxycycline during the treatment period ranged from 0.83 to 0.96 microgram ml-1. Thirty-six hours after the withdrawal from medicated drinking water, no plasma levels could be detected. Samples of medicated water were taken at time zero and at 24 h after addition of doxycycline to the drinking water. No statistically significant difference in the mean drinking water concentration was seen at time zero and at time 24 h (Student's t-test, alpha = 0.05).     

Catching the elusive persistent and mobile organic compounds: Novel sample preparation and advanced analytical techniques

Persistent and Mobile Organic Compounds (PMOCs) are emerging pollutants in the environment that have only been rarely detected in previous years due to the lack of analytical techniques available for their analysis. These compounds, being very polar, are able to spread through the surface waters, and reach groundwaters and drinking water sources. The challenges in the analysis of these compounds in water include their poor extraction efficiencies from environmental matrices and weak retention in conventional chromatographic columns. As a result, the toxicity and environmental fate of PMOCs are largely unknown. This review will examine recent developments in sorbent and chromatographic column technologies, and other sample preparation strategies that will enable analysis of PMOCs and advance our knowledge on their fate and transport in the environment. In addition, analysis of these compounds in water via liquid chromatography with tandem mass spectrometry (LC–MS/MS) are discussed in this review.     

Silver-Phosphonate Based Metal Organic Frameworks: Synthesis and Antibacterial Action

Silver based Metal Organic Framework (MOF) materials were synthesized by the reaction of phospho-benzoic acid with silver salts under hydrothermal treatment and with/without urea. According to this procedure, either both functional groups (phosphonic acid and carboxylic acid) were engaged in iono-covalent bonds with silver atoms or, on the contrary, only the phosphonic acid function is engaged. Consequently, these materials exhibited different stability and their ability to release silver salts, when they were placed in water, was different. The antibacterial properties of these materials were attributed to the silver salt, released in solution.     

The use of calix[6]arene molecules for actinides analysis in urine and drinking water: an alternative to current procedures

In this work the applicability of calix[6]arene columns for actinides analysis in urine samples and drinking water was investigated. A radiochemical procedure has been developed for U, Pu, Am analysis in urine. A simple and effective method has also been proposed on a specific column named AQUALIX, for the separation and preconcentration of U from drinking water. These procedures are suitable for routine analysis and require a considerably reduced number of steps of sample treatment as compared to current procedures.     

铁基水处理材料除砷技术的研究进展

自然环境中的砷污染问题被认为是全球最严重的环境威胁之一,人类长期暴露于含砷饮用水环境中会引起各种疾病的发生,因此,开发经济有效的除砷技术一直是砷污染治理领域的研究热点。铁基水处理材料由于其对砷的良好亲和力、表面反应活性强、价廉易制、便于回收等特点,一直备受关注。本文综述了近年来不同铁基水处理材料如铁(氢)氧化物、纳米零价铁、铁基多金属氧化物复合材料除砷技术的研究进展,论述了铁基水处理材料对水相中砷去除的影响因素及机理;同时,对影响铁基水处理材料砷解吸的因素和毒性评估研究进行了总结;指出了目前铁基水处理材料砷污染去除技术研究中存在的主要问题,并对水相砷污染去除技术研究中值得关注的重要发展方向进行了展望。