二硫化碳萃取毛细管柱气相色谱法测定水质的苯系物

采用二硫化碳萃取，DB—WAX毛细管柱分离，测定水中的苯系物，可在12min内有效分离7种苯系物，校准曲线线性好（r〉0．999），检测限可达0．002mg／L，与二硫化碳萃取填充柱气相色谱法检测限0．05mg／L相比，检测限有较大幅度降低，适用于地面水及废水监测。     

气相色谱法同时测定苯系物和汽油化合物

气相色谱法具有较高的灵敏度和良好的线性关系。按照EPA QA／QC的要求,将该方法运用于实际样品分析。结果表明。水中汽油检出限为0．04mg／L。水中苯系物检出限为0．003-0．005mg／L,土壤中汽油检出限为0．5mg／kg,土壤中苯系物检出限为0.005-0．008mg／kg。样品加标回收率为97．1％～106．8％。变异系数为2．1％～4．6％,结果令人满意。     

PEG-20M石英毛细管柱气相色谱法测定污水和废气中的醇类和苯系物

本文提到用PEG-20M石英毛细管柱气相色谱法测定污水和废气中的醇类和苯系物,使一柱多用。给出了操作条件,工作曲线相关性均在0.999左右。试验了苯系物标准混合液的保存时间。试验了精密度,变异系数均小于10％。     

分光光度法测定水和废水中六价铬的改进

对二苯碳酰二肼分光光度法测定水和废水中六价铬的方法进行了改进，取样量和所加试剂同比缩小10倍，于Hach公司COD消解管中进行显色反应，在其配套的分光光度计上直接比色测定，校准曲线相关性良好，r〉0．999，精密度RSD〈5％，加标回收率为92．0％～105％，满足分析要求。     

网络版论文摘要

正苯系物在红壤中垂向迁移的研究闫剑飞袁华焦峰邱丽娟刘佳(辽宁工程技术大学环境科学与工程学院,辽宁阜新123000)通过室内土柱淋溶实验,研究苯系物在红壤中垂向迁移及分布特征。在淋溶过程中收集淋滤液并对其进行检测以分析苯系物对地下水的潜在影响,在实验过程中,通过改变淋溶液的pH探讨酸性降水对苯系物在土壤中迁移影响。结果表明:(1)随着淋溶水的流动,苯系物在土壤中的含量随着土层深度增加而降低,各土层中乙苯含量最高,苯和甲苯     

潜流人工湿地-生物接触氧化处理低温低浓度生活污水

在低温低浓度生活污水的实验研究中，回流比和气水比是影响潜流人工湿地一生物接触氧化组合工艺污染物去除效果的重要因素，推荐回流比R=1．0，气水比为4：1，在该工况下，进水COD浓度在170．8～221．3mg／L时，平均去除率可达90％；进水NH3-N浓度在17．3～25．9mg／L，平均去除率45％～65％；进水TN浓度在25．1～38．49mg／L时，平均去除率45％～65％；进水TP浓度在2．2～3．1mg／L时，平均去除率65％～80％。污染物沿程浓度分析结果表明，该组合工艺可以在低温季节通过曝气促进氨氮硝化，大幅提高NH3-N和TN去除率，同时可以充分发挥复合潜流湿地功能。     

液—液萃取处理高氯难降解有机废水

农药化工厂生产苯肼、苯唑醇、乙基氯化物过程排放的废水是高氯鸡生物降解有机废水,采用三辛胺作萃取剂,用液－液萃取处理,三辛胺与水中Cl^-离子形成萃合物而使Cl^-1转移到有机相。再经高效絮凝处理后,CODCr总去除率达89．8％,Cl^-总去除率达83．2％,BOD／COD比从0．02上升到0．34,可生化性大幅度提高。     

土壤中四氯苯、六氯苯的测定

通过实验测定土壤中四氯苯、六氯苯的有机污染组分，详细介绍了样品的提取、净化与分析。该方法在0～150ug／L范围内，线性良好，其检出限分别是1，2，3，5四氯苯为1．2ug／kg，1，2，4，5四氯苯为2．0ug／kg，1，2，3，4四氯苯为2．0ug／kg，六氯苯为0．6ug／kg。     

新装饰装修房屋室内空气中的苯系物调查

对新装饰装修房屋室内的一类主要有机苯系污染物进行了调查,调查采用吸附柱采集、GC/MS 和GC-FID测定,检测了321家居室内的苯系物.检出的苯系物有12种,苯平均浓度为0.068 mg/m^3,有86.9%的居室符合《室内空气质量标准》（GB/T18883-2002）规定的限量值,甲苯、二甲苯平均浓度分别为0.14 mg/m^3和0.41 mg/m^3,符合《室内空气质量标准》规定限值的居室分别达85.4%和73.3%.苯系物约占室内空气中TVOC的62%,浓度由低到高分别是苯、甲苯、乙苯和二甲苯,其中二甲苯中的间二甲苯占二甲苯总量的55% .     

气相色谱法测定空气中的1，2-二氯乙烷

建立了一种用气相色谱法测定空气中1，2-二氯乙烷的方法。空气中1，2-二氯乙烷用活性炭吸附，二硫化碳解析，直接进样分析。其回收率为97．6％～100．8％，最低检出浓度为0．005mg／m^3，相对标准偏差为0．7％-2．4％；该方法具有前处理简单、速度快、干扰少、灵敏度高等特点，可用于空气中1，2-二氯乙烷的测定。     

Revealing source signatures in ambient BTEX concentrations

Management of ambient concentrations of Volatile Organic Compounds (VOCs) is essential for maintaining low ozone levels in urban areas where its formation is under a VOC-limited regime. The significant decrease in traffic-induced VOC emissions in many developed countries resulted in relatively comparable shares of traffic and non-traffic VOC emissions in urban airsheds. A key step for urban air quality management is allocating ambient VOC concentrations to their pertinent sources. This study presents an approach that can aid in identifying sources that contribute to observed BTEX concentrations in areas characterized by low BTEX concentrations, where traditional source apportionment techniques are not useful. Analysis of seasonal and diurnal variations of ambient BTEX concentrations from two monitoring stations located in distinct areas reveal the possibility to identify source categories. Specifically, the varying oxidation rates of airborne BTEX compounds are used to allocate contributions of traffic emissions and evaporative sources to observed BTEX concentrations.     

Measurement of Hydrocarbon Emissions Fluxes from Refinery Wastewater Impoundments Using Atmospheric Tracer Techniques

Sulfur hexafluoride (SF6) tracer was used in a series of the experiments to simulate emissions of benzene, toluene, ethyl-benzene, and xylenes (BTEX) from a refinery wastewater basin. The ratio of the measured tracer release to the ambient tracer concentration established a dilution factor which was then used to calculate the mass flux of BTEX from the wastewater basin using the ambient BTEX concentration data. Measured fluxes of BTEX varied from 7 g/min to 70 g/min.

The CHEMDAT7 air emissions model was then used to predict emissions for comparison with the emissions measured using the tracer flux simulation. CHEMDAT7 typically overpredicted total measured BTEX emissions by factors of twelve to seventeen. The degree of overprediction varied both by the individual compound and the module of CHEMDAT7 used to predict emission fluxes.     

Measurement of BTEX (benzene,toluene, ethybenzene,and xylene) levels at urban and semirural areas of Algiers City using passive air samplers

The study presents the levels of air pollution by aromatic organic compounds BTEX (benzene, toluene, ethylbenzene, o-, m-, and p-xylenes) in the city of Algiers. The sampling was carried out using Radiello passive sampler. Three sampling campaigns were carried out in roadside, tunnel, urban background, and semirural sites in Algiers. In order to determine the diurnal mean levels of air pollution by BTEX to which people are exposed, a modified passive sampler was used for the first time. In addition, monitoring of pollution inside vehicles was also made. In the spring of 2009, more than 27 samplings were carried out. In the background and road traffic sites the Radiello sampler was exposed for 7 days, whereas the time exposure was reduced to 1 day in the case of the vehicle as well as the tunnel. The results indicate that average benzene concentrations in the roadside and inside vehicle exceed largely the limit value of 5 μg m^?3 established by the European Community (EC). On the other hand, it has been noticed that the concentration levels of other BTEX are relatively high. Also, in order to identify the origin of emission sources, ratios and correlations between the BTEX species have been highlighted. This study shows that road traffic remains the main source of many local emission in Algiers.

Implications The vehicle fleet in Algeria is growing rapidly since the 1990s following economic growth and is responsible for the increasing air pollution in large cities. Because there are no data collection of BTEX carried out by national air quality network, all environmental and transportation policies are based on European emissions standards, but national emission standards are currently not in place. This work will contribute to the analysis of real emissions of BTEX in Algiers, for the development of management and for assessment of population exposure variation depending on the location in the city of Algiers.     

Indoor pollution and burning practices in wood stove management

This study evaluates effects of good burning practice and correct installation and management of wood heaters on indoor air pollution in an Italian rural area. The same study attests the role of education in mitigating wood smoke pollution. In August 2007 and winters of 2007 and 2008, in a little mountain village of Liguria Apennines (Italy), indoor and outdoor benzene, toluene, ethylbenzene, and xylene (BTEX) concentrations were measured in nine wood-heated houses. During the first sampling, several mistakes in heating plant installations and management were found in all houses. Indoor BTEX concentrations increased during use of wood burning. Low toluene/benzene ratios were in agreement with wood smoke as main indoor and outdoor pollution source. Other BTEX sources were identified as the indoor use of solvents and paints and incense burning. Results obtained during 2007 were presented and discussed with homeowners. Following this preventive intervention, in the second winter sampling all indoor BTEX concentrations decreased, in spite of the colder outdoor air temperatures. Information provided to families has induced the adoption of effective good practices in stoves and fire management. These results highlight the importance of education, supported by reliable data on air pollution, as an effective method to reduce wood smoke exposures.

Implications:Information about burning practices and correct installation and management of wood heaters, supported by reliable data on indoor and outdoor pollution, may help to identify and remove indoor pollution sources. This can be an effective strategy in mitigate wood smoke pollution.     

Household wood heater usage and indoor leakage of BTEX in Launceston,Australia: A null result

A study has been conducted in Launceston, Australia, to determine within households with wood heaters the effect of leakage from the heater and flue on the indoor air concentrations of the pollutants: benzene, toluene, ethylbenzene and xylene (BTEX). The study involved three classes: 28 households without wood heaters, 19 households with wood heaters compliant with the relevant Australian Standard and 30 households with non-compliant wood heaters. Outdoor and indoor BTEX concentrations were measured in each household for 7 days during summer when there was little or no wood heater usage, and for 7 days during winter when there was widespread wood heater usage. Each participant kept a household activity diary throughout their sampling periods. For wintertime, there were no significant differences of the indoor BTEX concentrations between the three classes of households. Also there were no significant relationships between BTEX indoor concentrations within houses and several measures of the amount of wood heater use within these houses. For the households sampled in this study, the use of a wood heater within a house did not lead to BTEX release within that house and had no direct detectable influence on the concentrations of BTEX within the house. We propose that the pressure differences associated with the both the leakiness or permeability of the building envelope and the draught of the wood heater have key roles in determining whether there will be backflow of smoke from the wood heater into the house. For a leaky house with a well maintained wood heater there should be no backflow of smoke from the wood heater into the house. However backflow of smoke may occur in well sealed houses.The study also found that wood heater emissions raise the outdoor concentrations of BTEX in winter in Launceston and through the mixing of outdoor air through the building envelopes into the houses, these emissions contribute to increases in the indoor concentrations of BTEX in winter in all houses in Launceston.     

Assessing the microbial activity of soil samples,its nutrient limitation and toxic effects of contaminants using a simple respiration test

Eight soil samples from five wells of a former gas plant site differing in the contamination with BTEX and PAHs as well as the nutrient content were investigated by soil respiration measurements. The basal, glucose as well as NH4+ and PO4(3-) induced cumulative oxygen consumption and carbon dioxide production in 72 and 120 h were determined and additionally the maximal turnover rates and the limitation quotients were calculated. Without additional carbon source only one of five investigated samples was clearly nutrient limited. After glucose supplementation four of seven investigated samples showed nutrient limitation that was in accordance with the available ammonium and phosphorous content. BTEX and PAHs did not exhibit an inhibiting effect on the respiration rate. In contrast, BTEX containing samples exhibited the highest oxygen consumption indicating biodegradation of the contaminants. The results show that oxygen consumption and carbon dioxide production as well as the kinetic of these processes are all informative parameters characterizing the whole microbial respiration potential and their nutrient limitation in soil samples. Therefore this fast respirometric method can be used for the decision if further detailed studies of the bioremediation are useful and if nutrient supplementation is recommended to enhance natural attenuation.     

Aromatic hydrocarbons in the atmospheric environment – Part II: univariate and multivariate analysis and case studies of indoor concentrations

The concentrations of the aromatic hydrocarbons benzene, toluene, ethylbenzene and the isomeric xylenes (BTEX) have been determined in the indoor air of 115 private non-smoker homes (∼380 individual rooms) situated in areas with an extreme traffic situation, i.e. in city streets (street canyons) with high traffic density and in rural areas with hardly any traffic at all. The influence of the traffic on the indoor concentration was apparent in the high traffic area. In order to identify other factors influencing the BTEX concentrations, the data and additional questionnaires were analyzed by univariate and multivariate analysis. The analysis was supplemented by some case studies. It is shown that meteorology (the seasons), the type of room (e.g. living room versus bedroom), the ventilation and, in particular, garages in the house strongly influence the indoor concentration of BTEX. Thus, the indoor BTEX level is significantly higher in winter than in summer. Moreover, garages with a connecting door to the living quarters lead to high indoor concentrations of aromatic hydrocarbons in these rooms. In addition, the storage of solvents and hobby materials, and also the presence of smoking guests increase the BTEX level. If rooms are directly heated by coal or wood, the BTEX level is higher compared to the use of gas heating. Surprisingly, no correlation was found between the building materials used and the BTEX level. Case studies were carried out for two homes with an integrated garage (and a connecting door to the living rooms) and for seven homes where redecoration work was carried out during sampling. In both instances, a pronounced increase was observed in the BTEX concentration.     

Aldehyde and monocyclic aromatic hydrocarbon mixing ratios at an urban site in Las Vegas, Nevada

Oxidation of benzene, toluene, ethylbenzene, and xylenes (BTEX) in air, of significance due to, for example, the potential for O3 formation, is believed to be initiated by OH attack on the ring (addition) or on the alkyl side chain (H abstraction). A series of ring-breaking reactions follows, with major products predicted to be alpha-dicarbonyls, simple aldehydes, and organic acids. To test this prediction, ambient air mixing ratios of aldehydes (formaldehyde, acetaldehyde, benzaldehyde, glyoxal, and pyruvaldehyde), along with some supporting BTEX data, were measured at an urban site in Las Vegas, NV. Samples were collected on sorbents and determined by chromatographic methods; mixing ratios were compared to ambient levels of CO, O3, and NOx. A meteorological analysis (temperature, wind speed, and wind direction) was also included. Statistically significant relationships were noted among the BTEX hydrocarbons (HCs) and among the photochemically derived species (e.g., O3, NO2, and some of the aldehydes), although there was seasonal variation. The observations are consistent with a common primary source (i.e., vehicular exhaust or fuel evaporation) for the BTEX compounds and a common secondary source (e.g., OH attack) for glyoxal and pyruvaldehyde.     

Assessment of indoor air concentrations of VOCs and their associated health risks in the library of Jawaharlal Nehru University,New Delhi

The present work investigated the levels of total volatile organic compounds (TVOC) and benzene, toluene, ethylbenzene, m/p-xylene, and o-xylene (BTEX) in different microenvironments in the library of Jawaharlal Nehru University in summer and winter during 2011–2012. Carcinogenic and non-carcinogenic health risks due to organic compounds were also evaluated using US Environmental Protection Agency (USEPA) conventional approaches. Real-time monitoring was done for TVOC using a data-logging photo-ionization detector. For BTEX measurements, the National Institute for Occupational Safety and Health (NIOSH) standard method which consists of active sampling of air through activated charcoal, followed by analysis with gas chromatography, was performed. Simultaneously, outdoor measurements for TVOC and BTEX were carried out. Indoor concentrations of TVOC and BTEX (except benzene) were higher as compared to the outdoor for both seasons. Toluene and m/p-xylene were the most abundant organic contaminant observed in this study. Indoor to outdoor (I/O) ratios of BTEX compounds were generally greater than unity and ranged from 0.2 to 8.7 and 0.2 to 4.3 in winter and summer, respectively. Statistical analysis and I/O ratios showed that the dominant pollution sources mainly came from indoors. The observed mean concentrations of TVOC lie within the second group of the Molhave criteria of indoor air quality, indicating a multifactorial exposure range. The estimated lifetime cancer risk (LCR) due to benzene in this study exceeded the value of 1?×?10^?6 recommended by USEPA, and the hazard quotient (HQ) of non-cancer risk came under an acceptable range.     

Risk factors for increased BTEX exposure in four Australian cities

Benzene, toluene, ethylbenzene and xylenes (BTEX) are common volatile organic compounds (VOCs) found in urban airsheds. Elevated levels of VOCs have been reported in many airsheds at many locations, particularly those associated with industrial activity, wood heater use and heavy traffic. Exposure to some VOCs has been associated with health risks. There have been limited investigations into community exposures to BTEX using personal monitoring to elucidate the concentrations to which members of the community may be exposed and the main contributors to that exposure. In this cross sectional study we investigated BTEX exposure of 204 non-smoking, non-occupationally exposed people from four Australian cities. Each participant wore a passive BTEX sampler over 24h on five consecutive days in both winter and summer and completed an exposure source questionnaire for each season and a diary for each day of monitoring. The geometric mean (GM) and range of daily BTEX concentrations recorded for the study population were benzene 0.80 (0.04-23.8 ppb); toluene 2.83 (0.03-2120 ppb); ethylbenzene 0.49 (0.03-119 ppb); and xylenes 2.36 (0.04-697 ppb). A generalised linear model was used to investigate significant risk factors for increased BTEX exposure. Activities and locations found to increase personal exposure included vehicle repair and machinery use, refuelling of motor vehicles, being in an enclosed car park and time spent undertaking arts and crafts. A highly significant difference was found between the mean exposures in each of the four cities, which may be explained by differences in fuel composition, differences in the mix and density of industry, density of motor vehicles and air pollution meteorology.