室内外细粒子PM_(2.5)和总悬浮颗粒物污染水平的对比研究

为了解室内外空气颗粒物PM2.5和总悬浮颗粒物(TSP)的污染状况,自2008年3月24日～4月3日在西安交通大学学生办公室、教师办公室、化学实验室和室外同时采集PM2.5和TSP样品,对其质量浓度及无机水溶性离子组分(Na+、NH4+、K+、Mg2+、Ca2+、Cl-、NO3-和SO42-)进行了分析。结果表明,室内外PM2.5和TSP浓度都远远高于美国空气质量标准规定的35μg/m3。室内外颗粒物浓度具有相同的变化趋势,且室内总体上低于室外。室内PM2.5在TSP中所占比例在65%～85%,室外在40%左右。室内外TSP和PM2.5中二次污染离子SO42-、NO3-和NH4+占总离子质量的50%以上,主要富集在细颗粒中。NH4+、K+和Cl-在总离子中的比例均为室内大于室外,PM2.5中大于TSP。Ca2+、Mg2+主要富集在粗颗粒上,室外含量远远高于室内。     

Emission control of SO2 and NOx by irradiation methods

Microwave discharges at 2.45 GHz frequency and accelerated electron beams operated at atmospheric pressure in synthetic gas mixtures containing N(2), O(2), CO(2), SO(2), and NO(x) are investigated experimentally for various gas mixture constituents and operating conditions, with respect to their ability to purify exhaust gases. An original experimental unit easily adaptable for both separate and simultaneous irradiation with microwaves and electron beams was set up. The simultaneous treatment with accelerated electron beams and microwaves was found to increase the removal efficiency of NO(x) and SO(2) and also helped to reduce the total required dose rate with approximately 30%. Concomitant removal of NO(x) ( approximately 80%) and SO(2) (>95%) by precipitation with ammonia was achieved.     

Gaussian Support Vector Machine Algorithm Based Air Pollution Prediction

Air pollution is one of the major concerns considering detriments to human health. This type of pollution leads to several health problems for humans, such as asthma, heart issues, skin diseases, bronchitis, lung cancer, and throat and eye infections. Air pollution also poses serious issues to the planet. Pollution from the vehicle industry is the cause of greenhouse effect and CO2 emissions. Thus, real-time monitoring of air pollution in these areas will help local authorities to analyze the current situation of the city and take necessary actions. The monitoring process has become efficient and dynamic with the advancement of the Internet of things and wireless sensor networks. Localization is the main issue in WSNs; if the sensor node location is unknown, then coverage and power and routing are not optimal. This study concentrates on localization-based air pollution prediction systems for real-time monitoring of smart cities. These systems comprise two phases considering the prediction as heavy or light traffic area using the Gaussian support vector machine algorithm based on the air pollutants, such as PM2.5 particulate matter, PM10, nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and sulfur dioxide (SO2). The sensor nodes are localized on the basis of the predicted area using the meta-heuristic algorithms called fast correlation-based elephant herding optimization. The dataset is divided into training and testing parts based on 10 cross-validations. The evaluation on predicting the air pollutant for localization is performed with the training dataset. Mean error prediction in localizing nodes is 9.83 which is lesser than existing solutions and accuracy is 95%.     

Simultaneous removal of SO2 and NO by wet scrubbing using aqueous chlorine dioxide solution

The present study attempts to generate chlorine dioxide (ClO(2)) gas continuously by chlorate-chloride process and to utilize it further to clean up SO(2) and NO(x) gases simultaneously from the flue gas in the lab-scale bubbling reactor. Experiments were carried out to examine the effect of various operating parameters like input SO(2) concentration, input NO concentration, pH of the reaction medium, and ClO(2) feeding rate on the SO(2) and NO(x) removal efficiencies at 45 degrees C. Complete oxidation of NO into NO(2) occurred on passing sufficient ClO(2) gas into the scrubbing solution. SO(2) removal efficiency of about 100% and NO(x) removal efficiency of 66-72% were achieved under optimized conditions. NO(x) removal efficiency decreased slightly with increasing pH and NO concentration. Input SO(2) concentration had marginal catalytic effect on NO(2) absorption. No improvement in the NO(x) removal efficiency was observed on passing excess of chlorine dioxide in the scrubbing solution.     

Simultaneous desulfurization and denitrification by microwave reactor with ammonium bicarbonate and zeolite

Microwave reactor with ammonium bicarbonate (NH(4)HCO(3)) and zeolite was set up to study the simultaneous removal of sulfur dioxide (SO(2)) and nitrogen oxides (NO(x)) from flue gas. The results showed that the microwave reactor filled with NH(4)HCO(3) and zeolite could reduce SO(2) to sulfur with the best desulfurization efficiency of 99.1% and reduce NO(x) to nitrogen with the best NO(x) purifying efficiency of 86.5%. Microwave desulfurization and denitrification effect of the experiment using ammonium bicarbonate and zeolite together is much higher than that using ammonium bicarbonate or zeolite only. NO(x) concentration has little effect on denitrification but has no influence on desulfurization, SO(2) concentration has no effect on denitrification. The optimal microwave power and empty bed residence time (EBRT) on simultaneous desulfurization and dentrification are 211-280 W and 0.315 s, respectively. The mechanism for microwave reduced desulfurization and denitrification can be described as the microwave-induced catalytic reduction reaction between SO(2), NO(x) and ammonium bicarbonate with zeolite being the catalyst and microwave absorbent.     

Environmental factors associated with crash-related mortality and injury among taxi drivers in New South Wales, Australia

This exploratory study aims to investigate the associations between some environmental factors and the increased risk of motor vehicle crash-related injuries among taxi drivers. Information utilised in the study are obtained from police reports of all road traffic accidents that occurred on the roads between 1996 and 2000 in New South Wales (NSW), Australia. Of the 7923 taxi drivers who involved in crashes, nearly 10% (n = 750) were killed or injured. Results indicate sex, and two environmental factors are significantly associated with an increased risk of crash-related mortality and injury among taxi drivers. The adjusted relative risk of crash-related mortality and injury is increased by 60% for those who work the night shift (OR = 1.59, 95%CI = 1.35-1.88), and by 20% for those who do not carry any passenger on board (OR = 1.20, 95%CI = 1.02-1.41) should these drivers involve in a crash. The increased relative risk of crash-related mortality and injury is nearly 2.5 times for female taxi drivers (OR = 2.30, 95%CI = 1.45-3.65) when compared with their male counterparts.     

Chemical ionization mass spectrometer instrument for the measurement of tropospheric HO2 and RO2

Laboratory characterizations of the peroxy radical chemical ionization mass spectrometer (PerCIMS) instrument have been performed. The instrument functions by drawing ambient air through a 50-microm-diameter orifice into an inlet held at low pressure. Peroxy radicals (HO2 and RO2) within this air are detected by amplified chemical conversion into a unique ion (HSO4-) via the chemistry initiated by the addition of NO and SO2 to the inlet. HSO4- ions are then quantified by a quadrupole filter mass spectrometer. PerCIMS provides measurements of the sum of peroxy radicals, HO2 + RO2 (HOxROx mode), or the HO2 component only (HO2 mode), achieved through the control of concentration of NO and SO2 added to the instrument. The characterization and response of this instrument have been evaluated through modeling of inlet chemistry and laboratory experiments and have also been demonstrated through successful deployment during field campaigns. The performance of PerCIMS with respect to calibration pressure and relative humidity is reported, as are the sensitivities of the instrument to organic peroxy radicals with different hydrocarbon groups. These data show PerCIMS to be a practical field instrument for the fast and accurate evaluation of the concentration of peroxy radicals over a variety of atmospheric conditions. The estimated accuracy of the derived [HOxROx] concentrations is +/- 35% (at the 95% confidence interval), while [HO2] measurements have accuracies of +/- 41% (at the 95% confidence interval). Typical precision of measurements well above the detection limit is 10%, and typical detection limits are 1 x 10(7) radicals cm(-3) for 15-s averaging times.     

A dual-use of DBD plasma for simultaneous NO(x) and SO(2) removal from coal-combustion flue gas

Dielectric barrier discharge (DBD) was investigated for the simultaneous removal of NO(x) and SO(2) from flue gas in a coal-combustion power plant. The DBD equipment was used in either a mode where flue gas was directed through the discharge zone (direct oxidation), or a mode where produced ozonized air was injected in the flue gas stream (indirect oxidation). Removal efficiencies of SO(2) and NO for both methods were measured and compared. Oxidation of NO is more efficient in the indirect oxidation, while oxidation of SO(2) is more efficient in the direct oxidation. Addition of NH(3), has lead to efficient removal of SO(2), due to thermal reaction, and has also enhanced NO removal due to heterogeneous reactions on the surface of ammonium salt aerosols. In the direct oxidation, concentration of CO increased significantly, while it maintained its level in the indirect oxidation.     

中国城市气溶胶危害评价

在环境受到污染的领域,气溶胶对人们生活和人体健康有重要影响。随着城市大气气溶胶污染日趋严重,对中国城市气溶胶危害进行评价十分必要,以便加以控制。本文对如下问题进行了讨论：气溶胶危害评价的领域和问题;空气污染与呼吸道疾病;中国城市空气悬浮颗粒总数（ＴＳＰ）和疾病,评价我国气溶胶对健康的作用;中国城市空气悬浮颗粒总数的主要化学组分,评价其卫生学作用;从卫生保健的角度进行小结和建议。     

Concentrations of ambient air particulates (TSP, PM2.5 and PM2.5-10) and ionic species at offshore areas near Taiwan Strait

The concentrations of total suspended particulate (TSP), fine particles PM(2.5) (with aerodynamic diameter <2.5 microm), coarse particles PM(2.5-10) (with aerodynamic diameter 2.5-10 microm,), and water-soluble inorganic ions were studied at two offshore sampling sites, Taichung Harbor (TH) and Wuci Traffic (WT), near Taiwan Strait in central Taiwan during March 2004 to January 2005. Statistical analyses were also carried out to estimate the possible sources of particulate pollution. Experimental results showed that the average mass concentrations of TSP, PM(2.5) and PM(2.5-10) at TH and WT sampling sites were 154.54 +/- 31.45 and 113.59 +/- 31.94 microg m(-3), 54.03 +/- 16.92 and 42.76 +/- 12.52 microg m(-3), and 30.31+/- 9.79 and 24.16 +/- 7.27 microg m(-3), respectively. The dominant inorganic ions at two sampling sites were SO(4)(2-), NO(3)(-), and NH(4)(+) for TSP and PM(2.5), but that were Ca(2+), Cl(-), and Na(+) for PM(2.5-10). The concentrations of most particulates and inorganic ions were higher in winter at both two sampling sites, and were higher at TH than WT sampling site in each season. From statistical analysis, air-slake of crust surface, sea-salt aerosols, agriculture activities, coal combustion, and mobile vehicles were the possible emission sources of particulate pollution at TH and WT sampling sites.     

Impact of nocturnal planetary boundary layer on urban air pollutants: measurements from a 250-m tower over Tianjin, China

It is well known that nocturnal planetary boundary layer (NPBL) has important effects on urban air pollutants. However, the direct measurements of the interactions between the NPBL height and urban air pollutants are normally difficult, because such measurements require continuous vertical profiles of air pollutants and meteorological parameters. This paper provides an unique data, which temperature, NPBL, NO(x) and O(3) concentrations are measured at a 250-m meteorological tower in the city of Tianjin, China (a much polluted city located in central-eastern China). The results are analyzed to study the trend of NPBL and the impacts of NPBL on air pollutants in the city. The results show that the measured NPBL height ranges from 100m to 150m. The measurement of 10-year trend of the NPBL height suggests that the averaged NPBL height increases by about 20% between 1995 and 2006. The results also show that the NPBL height has important effects on air pollutants. This study suggests that NO(x) and O(3) concentrations are strongly anti-correlated inside of the NPBL height. During nighttime, NO(x) is directly emitted from the surface and is limited to inside of NPBL (40m), resulting in high NO(x) concentrations near the surface. The high NO(x) concentrations depress O(3), producing low O(3) concentrations near the surface. The measurements of vertical gradient of O(3) show that about 30-50ppbv of O(3) concentrations are chemically destroyed due to the surface emission of NO(x) during nighttime, suggesting that NPBL plays important roles in regulating the diurnal cycle of O(3) at the surface.     

Absorption of lean formaldehyde from air with Na2SO3 solution

Formaldehyde is a major indoor pollutant over the world and its high release over the national standards in developing countries, such as China, harms people's health seriously. In this work, an investigation is carried out in a stirred vessel with a plain gas-liquid interface for the absorption of lean formaldehyde from pollution air by Na(2)SO(3) solution at 25 degrees C. Experiments are conducted with Na(2)SO(3) concentrations of 0.01-0.30kmolm(-3). The results show that the Na(2)SO(3) solution is an effective absorbent to remove lean formaldehyde from polluted air. The experiments reveal that the absorption rate is considerably influenced by the gas flow rate and formaldehyde concentration. The Na(2)SO(3) concentration has little effect on the absorption rate, and the loading content of formaldehyde reduces the absorption rate only if the formaldehyde concentration approaches or exceeds the concentration of Na(2)SO(3) solution. A theoretical model is developed and used to successfully calculate the absorption rate with the overall relative deviation of less than 15% to the experimental data. A possible process of the absorption method is also proposed in this paper. The analysis shows that the proposed process is feasible in removing formaldehyde from indoor air.     

活性炭纤维在治理水和大气污染中的应用

本文介绍了活性炭纤维的基本性能及其在水处理与大气污染中的应用。在水处理中的应用主要表现在净化用饮水以达到饮用标准和处理工业废水以达到排放标准 ,在治理大气污染方面主要体现在对有害气体如SO2 、NOx 和H2 S等的吸附。最后展望了活性炭纤维在环保领域的应用前景     

室内PM2.5浓度标准的探讨

PM 2.5在室内颗粒物中占有很大比例,由于具有比表面积大的特点,对多种有机物具有较强的吸附能力,可以直接进入肺泡,导致年总死亡率、心肺疾病死亡率以及肺癌死亡率的增加,对人体产生全方位的影响。所以将PM 2.5纳入我国室内空气质量检测范围和评价体系是加强空气污染防治、保障人体健康的必然要求。通过分析一些国家和国际组织的PM 2.5标准、我国《环境空气质量标准》及室内PM2.5的检测标准,对我国《室内空气质量标准》中PM2.5的浓度标准值进行探讨,为室内PM 2.5浓度的控制提出明确的目标与方向。     

Equilibrium studies on hydrolysis of urea in a semi-batch reactor for production of ammonia to reduce hazardous pollutants from flue gases

The increasing environmental awareness and the mandate of the pollution control agencies in various part of country for lowering emission of air pollutants such as CO(2), NO(x), SO(2) and fly ash emissions, has increased the urgency for reviewing options and alternatives to accomplish the above objective. The addition of ammonia into the flue gas stream as a conditioning agent is found to be used in recent years for the reduction of air pollutants. Flue gas conditioning requires in situ generation of ammonia as the transportation and storage of anhydrous ammonia is hazardous in nature. The equilibrium study on hydrolysis of urea was done in a semi-batch glass reactor to investigate the effect of reaction temperature, initial feed concentration and stirring speed on ammonia production. Few experiments were carried out in a semi-batch reactor at atmospheric pressure by using different concentration of urea solution from 10 to 40 wt% of urea to water and equilibrium study has been done. The study reveals that conversion increases exponentially with an increase in temperature but the conversion decreases with increase in the inlet feed concentration of urea solution. Furthermore, the effect of stirring speed on conversion has also been studied and it found that conversion increases with increase in stirring speed.     

Mn-Cu-La/TiO_2低温催化剂催化还原氮氧化物性能研究

采用浸渍法制备了Mn-Cu-La/TiO2催化剂,研究了其组分配比、焙烧温度等制备条件和NO进口浓度、空速、O2含量、NH3/NO摩尔比等操作条件对Mn-Cu-La/TiO2上NH3低温还原NO活性的影响;探讨了H2O、SO2对Mn-Cu-La/TiO2活性的影响.结果表明,该催化剂具有很好的低温SCR活性,空速为10 000h-1,反应温度为150℃下时NO转化率接近99.6%.180℃下同时通SO2、H2O后的360min内,活性始终保持在95%以上;单独通入SO2时,该催化剂较容易中毒;单独通入体积分数10%的H2O对催化剂活性基本没有影响,转化率始终保持在98%以上.     

Modeling mobile source emissions in presence of stationary sources

The impact of oxides of nitrogen (NO(x)) emissions from motor vehicles to the air quality in city-state Singapore is analyzed using AIRVIRO, a regional scale dispersion model developed by the Swedish Meteorological and Hydrological Institute. In a predominantly urban location like Singapore, it is difficult to separate out the contribution of pollutants from mobile and point sources at different locations. In this work, a new approach is used by first modeling only the impact of point and area sources and then overlaying the traffic impact on air quality at different locations. Monthly scenario simulations are run with point, area and traffic sources of emissions for the Gaussian model validation. Street Canyon modeling is used for street segments surrounded by buildings on either side. A simplified photochemical model, which takes into account NO(x) undergoing chemical transformations in the urban atmosphere, is used to account for variations in NO(x) and ozone levels with respect to traffic data. The diurnal variation of NO(x) concentration levels is studied as a function of ozone levels at site, hourly traffic counts and meteorological parameters. The impact on ambient air quality within the breathing zone of the public from mobile sources, is found to be about 40% at urban stations although overall emissions from mobile sources is only 24%. The proposed approach appears to predict the variations in NO(x) as a function of traffic and meteorological conditions.     

Understanding on-road practices of electric bike riders: An observational study in a developed city of China

Although millions of electric bikes (E-bikes) operate in China and many associated deaths and injuries have been reported, E-bikers’ on-road practices are poorly characterized and few direct observational studies have been performed. This study aims to describe riding behaviors among E-bikers and to investigate factors influencing these practices to inform injury prevention. In March 2012, a cross-sectional observational study was conducted at 14 randomly selected intersections in Suzhou during a 7-day period. A pro-forma observation checklist was used to collect data on road riding practice. Adjusted Odds Ratios (OR) and 95% Confidence Intervals (CI) to assess the likelihood of specific riding practices among E-bikers were evaluated using mixed-effects logistic regression. Among 18,150 E-bikers observed, 37.6% rode E-bikes with cycling pedals, 86.0% of E-bikes were registered, 26.6% did not comply with the road rules, and 41.1% wore at least one safety item. The overall prevalence of carrying passengers, riding in a motor vehicle lane, running red lights, riding in opposite directions (i.e., facing oncoming traffic), mobile phone use, and helmet use were 12.4% (95%CI: 11.9–12.9%), 1.9% (95%CI: 1.7–2.1%), 4.8% (95%CI: 4.5–5.1%), 3.4% (95%CI: 3.1–3.7%), 0.4% (95%CI: 0.3–0.5%), and 9.0% (95%CI: 8.5–9.4%), respectively. Male E-bikers was associated with increased helmet use and riding in motor vehicle lanes, whereas riding a registered E-bike was associated with reduced likelihood of carrying passengers. This study demonstrates common road rule violations and low helmet use among E-bikers and supports the urgent need to develop additional regulations and behavioral interventions to improve safety practice among E-bikers in China.     

热电厂连续监测系统CEMS烟气污染物测量不确定度研究

烟气排放连续监测系统(CEMS)已经广泛运用于热电联产机组烟气污染物排放监测中,并且测试数据实时上传到生态环境部门。为了评估某热电厂CEMS系统监测数据的准确度和可信度,分析了该系统中影响烟气污染物测量不确定度分量因素,主要包括零点漂移、量程漂移、示值误差、测量误差、标准气体组分浓度和测量重复性。结果表明当包含因子 k=2,置信概率为95%时,SO2、NO和NO2的扩展不确定度分别为2.28mg/m³、3.50mg/m³和0.50mg/m³。由于参比法与CEMS对烟气监测的采样方式不同,使测量误差引入的不确定度分量最大。