机动车来源多环芳烃及其衍生物的排放特征研究进展

随着机动车保有量快速增长,机动车排放成为大部分大中城市大气中PAHs及其衍生物的主要来源之一。因此,基于以往的研究成果,汇总了台架实验、车载实验、隧道实验、路边实验等常用的机动车尾气采集方法,对机动车来源PAHs及其衍生物的排放特征（排放因子、气粒分配规律、成分谱研究以及机动车车型、工况和行驶里程的影响等）进行了总结,为不同研究需求下实验方法的选取以及机动车减排措施的制定提供科学参考。此外,为缓解能源问题和机动车排放污染问题,中国计划2020年在全国范围内推广使用车用乙醇汽油。由于乙醇汽油与普通汽油的性质存在诸多不同,乙醇汽油对机动车排放的影响也引起了研究者们的关注,因此分析了乙醇汽油实施对机动车尾气PAHs及其衍生物的污染特征变化的影响,以期为该领域未来的研究方向提供建议,为机动车污染防控研究提供科学合理的参考。      

关于“十一五”机动车尾气净化催化剂的规划与建议

一、机动车尾气净化催化剂的科学技术特征及未来的发展趋势 1．1技术特征 机动车尾气中含有HC、CO和NOx等污染物，当机动车尾气大量排出时，必将严重危害人类的身体健康。机动车尾气净化催化剂能有效地将HC、CO和NOx转化为CO2、H2O和N2，从而消除尾气对人体的污染。满足欧Ⅱ排放标准只需要一种机动车尾气三效催化剂（TWC）；但满足欧Ⅲ及以上排放标准（包括欧Ⅳ，欧Ⅴ，欧Ⅵ和零排放）则需要由密偶催化剂（CCC）十三效催化剂（TWC）两部分来完成。机动车尾气净化催化剂的科学及技术特征如下：     

化油器式汽车发动机尾气排放成因及控制

阐述了汽车发动机尾气排放的形成及其影响因素。结合本单位近几年来汽车年检、二级维护和技术评定检修过程中尾气排放调整控制的实践，总结出了化油器式汽车发动机尾气排放的调整工艺。     

新型机动车尾气净化器在津推广

由天津帅洁公司自主研发的新型合成材料机动车尾气净化器,日前通过专家鉴定,并已在天津市出租车上推广应用。经科技部科技查新工作站查核,此项技术在国内外汽车尾气净化领域尚属首创。这种新的机动车尾气净化器采用陶制合成磁石、集成多种元素制成,可使燃油及其所含杂质得以充分燃烧,尾气排放得到有效控制。经检测,机动车安装该产品后,汽油发动机尾气削减率达60％,柴油发动机尾气削减率达55％;同时,可分别降低汽油、柴油单位消耗20％以上。不仅可以减少污染排放,改善环境质量,而且具有显著的节能降耗综合效益,为进～步加大城市汽车尾气治理力度提供了技术支持和产品配套。     

炼焦过程中多环芳烃排放特性及影响因素

以炼焦过程中排放的多环芳烃(PAHs)为研究对象,分析了PAHs的排放规律以及温度、热解产物和PAHs的特性、挥发分对多环芳烃产生排放的影响。通过对3种单煤和配合煤进行实验室炼焦、超声波萃取和高效液相色谱的检测,测定了炼焦过程中各阶段产生排放的16种PAHs浓度。结果发现:在结焦初期1～5 h内PAHs产生排放量最多,并且在整个炼焦过程中产生排放量逐渐减少。PAHs化学性质不稳定使得炼焦初期PAHs的产生排放量较大,且低环PAHs产生排放较多。在挥发分小于26%时,PAHs产生排放量随着挥发分的增大而减小。     

“高性能储氧材料和满足欧Ⅲ排放标准的机动车尾气净化催化剂及产业化”科技成果通过鉴定

6月25日，四川大学科技园在孵企业——四川中自尾气净化有限公司的“高性能储氧材料和满足欧Ⅲ排放标准的机动车尾气净化催化剂及产业化”项目，顺利通过了四川省科技厅和四川省发展和改革委员会组织的成果鉴定。经过专家们的严格审查、评议，确定该成果已达到国外同等产品的技术水平。     

纳米CeO2对乳化重油燃烧性能的影响

利用沉淀法制备了纳米氧化铈,并用X射线衍射仪和透射电子显微镜对其结构进行表征.考察了不同含量的纳米氧化铈对乳化重油燃烧效率及尾气排放量的影响.结果显示,纳米氧化铈能有效地降低有害废气的排放,当纳米氧化铈含量为0.2%时,SO2排放降低了24%,NOx排放降低了62%.     

我国机动车排放污染控制与稀土催化剂的应用

本文从我国机动车排放污染的现状、机动车排放的法规与政策、国内外排放污染控制技术、稀土催化剂的研究与机动车净化催化剂中稀土的催化特性和机动车尾气净化催化剂研发中存在的问题等方面进行了综述与探讨 ,得到了一些有意义的结论 ,就机动车尾气净化稀土催化剂的研究与开发提出了一些设想和建议。     

不同料层高度烧结过程尾气排放规律

研究了不同料层高度下烧结过程中尾气成分(O₂、CO₂、SO₂和NO)的变化规律.结果表明:随着烧结历程的推进,尾气中O₂含量降低而CO₂含量升高,这主要是因为固体燃料燃烧量逐渐增多;尾气中SO₂、NO的含量亦呈升高趋势,但幅度很小,这主要是因为烧结料层对SO₂有吸收作用,而燃烧带的CO气体则可以还原使部分NO分解;在临近烧结终点时,因料层对SO₂的吸收作用消失而使析出作用强化,导致尾气中SO₂含量急剧升高.另外,随着料层高度的增加,因固体燃料配比相应减小,尾气中CO₂、SO₂和NO的含量降低,而O₂含量增加.因此,控制高温区宽度的厚料层烧结技术是我国开展减少烧结尾气中气体污染物(CO₂、SO₂和NO)的有效措施.     

东莞市农业土壤多环芳烃污染及其空间分布特征研究

选取位于珠江三角洲的东莞市为研究区域,采集59个代表性表层农业土壤样品,分析了16种优控PAHs的含量.结果显示,13种PAHs检出率均在90%以上,其中Fle,Phe,Chr和Bbf的检出率为100%,Ant的检出率最低(13.56%).∑PAHs介于29～2184μg/kg之间,远超出土壤内源性PAHs含量,分别有44.07%,8.47%和3.39%的土壤样品达到了PAHs的轻、中、重度污染水平.主成分分析及源解析结果表明,该市农业土壤PAHs主要有燃烧源、石油源和煤燃烧源3个主要来源.与国内其他地区相比,东莞市农业土壤PAHs含量处于相对较高的水平.还对可能影响PAHs环境行为的因素进行了分析,认为环境因素(温度、湿度、光照)、土壤性质(pH值、有机质含量)以及其他污染物(重金属)均会对PAHs环境行为产生影响.采用克里格插值法对东莞市农业土壤PAHs的空间分布特征进行了分析,发现不同PAHs组分的空间分布差别很大,总体上该市西北部土壤PAHs含量较高,PAHs异常的富集中心在东莞市望牛墩镇附近,该区域可能存在一些有毒废物焚烧污染源.     

Contribution of Traffic-Generated Nonexhaust PAHs, Elemental Carbon, and Organic Carbon Emission to Air and Urban Runoff Pollution

Emissions of polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC), organic carbon (OC), and size distributions of particulate matter from summer tire-concrete road interaction were studied. Based on particle size distribution, particles were categorized in three groups: (1) PM10?(0.02%); (2) PM10–100?(44.20%); and (3) PM100–2,000?(55.78%). The emission factor for total of four PAHs [fluoranthene, phenenthrene, pyrene, and benzo(ghi)perylene] was estimated as 378?ng?tire?1?km?1 for small cars (engine displacement volume ? 1,000?cm3; load ? 170?kg?tire?1). Out of eight PAHS analyzed in particles (all sizes), the main PAH compounds were pyrene (54%) and benzo(ghi)perylene (21%). Emission factors for EC and OC were 1.46 and 2.37?mg?tire?1?km?1.     

Cancer risk from occupational and environmental exposure to polycyclic aromatic hydrocarbons

Epidemiologic evidence on the relationship between polycyclic aromatic hydrocarbons (PAH) and cancer is reviewed. High occupational exposure to PAHs occurs in several industries and occupations. Covered here are aluminum production, coal gasification, coke production, iron and steel foundries, tar distillation, shale oil extraction, wood impregnation, roofing, road paving, carbon black production, carbon electrode production, chimney sweeping, and calcium carbide production. In addition, workers exposed to diesel engine exhaust in the transport industry and in related occupations are exposed to PAHs and nitro-PAHs. Heavy exposure to PAHs entails a substantial risk of lung, skin, and bladder cancer, which is not likely to be due to other carcinogenic exposures present in the same industries. The lung seems to be the major target organ of PAH carcinogenicity and increased risk is present in most of the industries and occupations listed above. An increased risk of skin cancer follows high dermal exposure. An increase in bladder cancer risk is found mainly in industries with high exposure to PAHs from coal tars and pitches. Increased risks have been reported for other organs, namely the larynx and the kidney; the available evidence, however, is inconclusive. The results of studies addressing environmental PAH exposure are consistent with these conclusions.     

Hydroxychloroquine: past, present, future

OBJECTIVE: To examine the trends in motor vehicle exhaust gas suicides since 1970 and to investigate the impact of catalytic converters. DESIGN: Australia-wide database analyses and a retrospective stratified series of 100 Victorian cases. DATA SOURCES: Australian Bureau of Statistics, 1970-1995; Australian Institute of Health and Welfare, National Injury Surveillance Unit, 1991/92-1995/96; Victorian Coroner's files, 1994-1996. RESULTS: There were 509 motor vehicle exhaust gas suicides in Australia in 1995, representing 22% of total suicides. Since the 1986 requirements for reduced carbon monoxide emissions from new vehicles (and thus the use of catalytic converters), the absolute numbers and rates of such suicides have increased, and they have come to represent a larger percentage of total suicides. Of 75 Victorian victims' vehicles traced, 36% were manufactured during or after 1986, showing that exhaust gas suicides have occurred in vehicles with catalytic converters. Blood carboxyhaemoglobin levels did not differ between victims using vehicles with or without catalytic converters. Between 1976 and 1991 exhaust gas suicides increased at a faster rate than motor vehicle registrations. Australian hospital admissions for exhaust gas suicide attempts have increased substantially since 1991-1992. CONCLUSION: Catalytic converters and the associated lower CO emission limits of 9.3 g/km had not, by 1995, resulted in a reduction in numbers, rates or percentages of exhaust gas suicides in Australia.     

Polycyclic aromatic hydrocarbons (PAH) and diesel engine emission (elemental carbon) inside a car and a subway train

Significant concentrations of potentially harmful substances can be present in the interior of vehicles. The main sources of PAHs and elemental carbon (EC) inside a car are likely to be combustion emissions, especially from coal and traffic. The same sources can also be important for the interior of a subway train for which there are specific sources in the tunnel system, for example diesel engines. Twice, in summer 1995 and winter 1996 polycyclic aromatic hydrocarbons (PAH) and diesel motor emission (estimated as elemental carbon) were determined in the interior of a car (a 2-year-old VW Golf with a three-way catalytic converter) and in the passenger compartment of a subway train (below ground). On each sampling day (in total 16 daily measurements in the car and 16 in the subway) the substances were determined in the breathing zone of the passengers from 07:00 h to 16:00 h under different meteorologic conditions (winter- and summertime). The car followed the route of the subway from the western Berlin borough of Spandau to the south-eastern borough of Neuk?lln, and back. The sampling represented a realistic exposure model for driving in a high traffic and polluted urban area. The electric subway train (also 2 years in use) connected the same parts of Berlin (31 km underground). The mean values obtained during the two measurement periods (summer/winter) inside the car were 1.0 and 3.2 ng/m3 for benzo[a]pyrene, 10.2 and 28.7 ng/m3 for total-measured-PAHs, 14.1 and 8.2 micrograms/m3 for EC and in the subway 0.7 and 4.0 ng/m3 for benzol[a]pyrene, 30.2 and 67.5 ng/m3 for total PAHs, 109 and 6.9 micrograms/m3 for EC. A comparison between subway and car exposures shows significantly higher concentrations of PAHs in the subway train, which can be explained by relatively high concentrations of fluoranthene and pyrene in the subway. So far a satisfactory explanation has not been found, but one source might be the wooden railway ties which were formerly preserved with tar based products. In wintertime in both transportation systems the concentrations of beno[a]pyrene are three to four times higher than in summer corresponding to the changing of the ambient air concentrations.     

Reducing the risk of accidental death due to vehicle-related carbon monoxide poisoning

Emissions of carbon monoxide (CO) from motor vehicles cause several hundred accidental fatal poisonings annually in the United States. The circumstances that could lead to fatal poisonings in residential settings with motor vehicles as the source of CO were explored. The risk of death in a garage (volume = 90 m3) and a single-family dwelling (400 m3) was evaluated using a Monte Carlo simulation with varying CO emission rates and ventilation rates. Information on emission rates was obtained from a survey of motor vehicle exhaust gas composition under warm idle conditions in California, and information on ventilation rates was obtained from a summary of published measurements in the U.S. housing stock. The risk of death ranged from 16 to 21% for a 3-hr exposure in a garage to 0% for a 1-hr exposure in a house. Older vehicles were associated with a disproportionately high risk of death. Removing all pre-1975 vehicles from the fleet would reduce the risk of death by one-fourth to two-thirds, depending on the exposure scenario. Significant efforts have been made to control CO emissions from motor vehicles with the goal of reducing CO concentrations in outdoor air. Substantial public health benefit could also be obtained if vehicle control measures were designed to take account of acute CO poisonings explicitly.     

Research advances of rare earth catalysts for catalytic purification of vehicle exhausts-Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

Nowadays,air pollution has become a prominent environmental problem and has attracted much attention.With the increase of vehicle retention quantity,the exhaust emissions have become the main sources of air pollution.To reduce pollution and hazards,vehicle exhaust emission regulations are becoming stricter and stricter,which puts forward higher requirements for purification of vehicle exhausts.At present,rare earths have been widely applied in vehicle exhaust purification because of their good catalytic performance,which is attributed to their unique 4 f electron layer structure occupied without full electrons,excellent oxygen storage/release capacity and redox ability.In this paper,the current status of rare earth catalysts and application of rare earth in different fuel vehicle exhaust catalysts,including three-way catalysts(TWCs) for gasoline vehicles,diesel exhaust catalysts for different pollutants(particulate matter(PM),NO_x,CO and HC) and catalysts for new energy vehicles with different fuels,are summarized in detail.Meanwhile,the corresponding mechanisms and the role of rare earth in vehicle exhaust catalysts are also simultaneously described.Furthermore,the challenges and development directions of rare earth catalysts for the purification of vehicle exhausts are also proposed.     

Using 3'' untranslated sequences to identify differentially expressed genes in Leishmania

Because garbage collectors work in the street, they are exposed to polycyclic aromatic hydrocarbons (PAHs) in motor vehicle exhaust gas as they work. Urinary 1-hydroxypyrene (1-OH-pyrene) began to be used as a biological monitoring index for human exposure to high concentrations of PAHs. The objective of this study was to examine the applicability of urinary 1-OH-pyrene as a biological monitoring index for human low-level PAH exposure, such as the PAH exposure experienced while working in the street. The subjects were fifteen male garbage collectors. We measured individual exposure to PAHs, urinary 1-OH-pyrene concentrations and urinary cotinine concentrations. Individual air samplers were attached to the collar of the clothing of five workers to capture PAHs. Urine samples were collected before work, around noon and after finishing the day's work. In all, five PAH samples and 45 urine samples were collected. As control data, we analyzed the urinary 1-OH-pyrene and urinary cotinine levels of six smoking and four non-smoking control subjects who were not occupationally exposed to PAHs. The benzo[a]pyrene level in the air sampled for 5-6 h was 2.5-10.5 ng/m3, and the pyrene level as 10.3-70.3 ng/m3. These levels were similar to those in the vicinity of streets in Japan. A positive correlation between total PAH levels and the pyrene levels was observed. The average urinary 1-OH-pyrene level of the smokers was 0.21 +/- 0.13 mumol/mol creatinine, vs. 0.15 +/- 0.11 mumol/mol creatinine in the non-smokers. The urinary 1-OH-pyrene level obtained in this study was slightly higher than in the control group. No correlation was found between pyrene exposure and the urinary 1-OH-pyrene level of the five workers who wore the personal samplers. A significant positive correlation was observed between the urinary 1-OH-pyrene level and urinary cotinine level of the smokers. A significant positive correlation was also observed between the urinary 1-OH-pyrene and urinary cotinine levels of the control group smokers. In conclusion, urinary 1-OH-pyrene is not applicable for biological monitoring of extremely low levels of exposure to PAHs, as in the case of working in the street. Caution is required to exclude the effects of smoking when evaluating PAH exposure.     

Requirements and Incentives for Reducing Construction Vehicle Emissions and Comparison of Nonroad Diesel Engine Emissions Data Sources

Nonroad construction vehicles and equipment powered by diesel engines contribute to mobile source air pollution. The engines of this equipment emit significant amounts of carbon monoxide, hydrocarbons, nitrogen oxides, and particulate matter. These pollutants pose serious problems for human health and the environment. Therefore, it is necessary to regulate and control the levels of these pollutants. Furthermore, there are emerging requirements and incentives for “greening” of construction vehicle fleets and operations. Currently, there are two types of standards that regulate air pollution for these types of vehicles: technological standards for engines and quality standards for air. It is also necessary to quantify the levels of emissions that nonroad construction vehicles and equipment produce. Quantification may be based on existing data sources (such as the EPA NONROAD model) or by collecting data directly from the vehicles as they work in the field. The purpose of this paper is to introduce the challenges to quantification of emissions from nonroad construction vehicles, describe associated governmental regulations and incentives for reducing emissions, identify and compare various sources of emissions data, establish the need to collect additional data, and propose a future research agenda that focuses on air pollution generated by construction vehicles.     

Control of PAHs from Incineration by Activated Carbon Fibers

The aim of this research was to use activated carbon fibers (ACFs) to adsorb 16 polycyclic aromatic hydrocarbon (PAH) species from flue gas emissions during incineration. The operation conditions included the presence of three activated carbon fibers, the adsorption temperature (200, 300, and 340°C), and the weight of the ACFs. The removal efficiencies of the gaseous and solid-state PAHs were evaluated respectively. It was found that the BET surface area did not affect PAH removal when the BET surface area was enough for PAH removal and micropore volume was the determinant parameter for PAHs removal. The best adsorption temperature in this study was 300°C. The removal efficiency of PAHs was proportional to the weight of ACFs.