中国铅污染的调查研究

阐述了中国铅污染的调查结果,包括:历史回顾、群体铅中毒事件、燃油铅污染、燃煤铅污染、铅中毒率统计和防治研究等6个部分。历史回顾从人类对铅污染危害认识的3次飞跃,反映了铅污染由公共卫生问题上升为人类社会问题;中毒事件调查,告诉人们企业的违规排铅,是铅中毒事件的罪魁祸首;燃油污染调查结果表明,汽油无铅化后,燃油大气铅年排放量比从前平均降低了98%左右;燃煤污染的调查结果表明,中国燃煤铅排放量年均增长9.55%,到2010年,中国燃煤铅排放量突破14 000 t,是汽车尾气铅排放量的35倍,且燃烧大气铅排放量与儿童铅中毒率之间存在显著的正相关关系;中毒率的调查结果表明,2003—2007年中国儿童铅中毒率平均为23.61%,比1994—2003年的35.27%有显著降低,但2007年为23.5%,比2006年的17.2%有所反弹;防治研究指出,中国对铅的研究主要是涉及铅毒理和铅污染防治等方面的研究,2006年发表铅文献量接近1 600篇。防治对策是污染源控制和人群监测,发铅与血铅监测同样可靠。     

汽油无铅化后中国儿童铅中毒现状、污染源及防治对策

汽油无铅化后,我国儿童铅中毒问题仍相当严重,群体铅中毒事件频频发生,铅中毒流行率相对较高且有回升趋势,膳食铅摄入量过高。在各类铅污染源中,燃煤铅排放已成为大气铅污染的重要贡献者,初步估算表明,2001—2005年燃煤大气铅排放总量达4.5万t,铅排放量与铅中毒率之间呈显著相关关系。预防铅中毒应切实加强环境污染的有效控制和敏感人群的定期监测,铅中毒监测亦应采取血铅测定和发铅测定双管齐下的方针。     

1953—2005年中国燃煤大气铅排放量估算

采用随时间变化的铅排放因子估算了中国1953—2005年燃煤大气铅排放量。在52年间,中国燃煤累计向大气排放19.1万t铅,平均每年以4.02%的速度增加,其中2001—2005年排铅38 688 t,平均增速达9.55%;工业用煤的铅排量占总量的87%,生活用煤铅排量占8%;2006年的燃煤铅排量超过了10 000 t。这表明,燃煤造成的铅污染已成为当前中国面临的重要环境问题。     

汽油铅与血铅的关系

论述了汽油铅对人体血铅水平的影响，主要内容包括：血铅水平与大气铅水平的关系，大气铅水平与加铅汽油耗量的关系，汽油铅耗量与居民血铅水平的关系。     

2001—2005中国各省(市)燃煤大气铅排放量估算

首次估算了中国各省(市)燃煤大气铅排放量和铅排放强度。结果表明,在2001—2005年,山西、湖北、山东、河北、河南的燃煤铅排量均超过3 000 t,各省(市)共向大气排铅5.9万t,年平均增长速度达14.5%。燃煤大气铅排放强度与儿童铅中毒率之间存在复杂的相关关系,在人口铅排强度低于0.5 t/万人的省(市),两者呈显著负相关关系;而在人口铅排强度超过0.6 t/万人的省(市),两者呈极显著正相关关系。     

荧光指示剂吸附法测定汽油中烯烃含量的研究

随着我国汽车拥有量的迅猛发展,汽车尾气污染已成为重要的环境污染之一。该污染是由于汽油中含有铅、芳烃和烯烃,减少污染必须控制汽油中的这3种物质的含量。铅作为主要抗爆剂燃烧后排到大气中,85%直接污染环境;芳烃作为汽油中的高辛烷值组分之一,燃烧会导致尾气中有毒物质的排放,增加发动机燃烧室的沉积,并使尾气排放增加;烯烃作为不饱和烃类物质,有较好的抗爆性,但热稳定性差,容易堵塞发动机喷嘴,因此《车用无铅汽油》[1]国家标准中规定汽油中芳烃含量必须不大于40%,烯烃含量不大于35%。根据我国炼油工艺,大部分炼油企业在生产汽油时芳烃…     

汽油中痕量铅的电感耦合等离子体质谱法同位素比值分析

为建立汽油中痕量铅的等离子体质谱的同位素比值分析方法,考察使用了不同的样品处理手段处理汽油样品。结果表明,V(HNO3) V(H2O)=1 10体系萃取汽油,为汽油中同位素比值分析的最佳方法,其操作安全简单,方便快速,且灵敏度高,从而有效保证同位素比值分析的精确度。利用等离子体质谱仪对汽油中痕量铅的实际含量进行了分析,为配合城市大气铅污染来源调查工作提供了一种极为快速简捷、安全有效的手段。     

美国预防铅中毒的成功经验

一般居民的铅暴露有 3个主要来源 ,即 :汽油铅、含铅油漆和铅质焊锡。针对铅污染的严重状况 ,美国政府采取了严格的初级预防措施。从 2 0世纪 70年代中期开始 ,美国政府开始致力于降低汽油中铅含量的工作 ,1 982年美国国家环保总署下决心逐步降低汽油中的铅含量和取消含铅汽油的使用。在 1 976年时 ,美国汽油用铅达 2 0 5 81 0ｔ,到 1 983年降到 5 6940ｔ,而到 1 990年 ,汽油铅用量已降到 5 2 0ｔ。即从 1 970年到 1 990年 ,美国用于汽油的铅降低了 99 8%。在限制含铅油漆的使用方面 ,2 0世纪 70年代初 ,美国总统签署了“含铅油漆中毒预防法…     

汽油中铅定性方法的研究

城市空气中的铅主要来自汽车尾气的排放 ,铅是一种累积物 ,不宜分解 ,对人体尤其是婴幼儿和孕妇危害极大。因此我国许多城市都在积极推广使用无铅汽油。目前汽油中铅的分析方法 (ＧＢ/Ｔ80 2 0 -1987)采用原子吸收法 ,使用的试剂稀缺价格昂贵且难买。为此本文建立了测定汽油中铅的快速定性方法。该方法简单 ,灵敏度高 ,非常适合于大批汽油样进行筛选以确定汽油是否属于无铅汽油。1　试验部分1.1　试剂铅标准溶液 :称取氯化铅 0 .2 771ｇ溶于热水中 ,冷却至室温 ,稀释成 10 0ｍｌ,铅浓度为 0 .0 1ｍｏｌ·Ｌ- 1或为 2 .0 7ｍｇ·ｍｌ- 1。铅…     

大气中的“无形杀手”

稍有常识的人都知道，汽油是从石油中提炼出来的，它本身不含铅。由于汽油的燃点很低，为了提高它的抗爆性能，１９２１年，美国人最早往汽油中加入四乙基铅。四乙基铅加得越多，抗爆性能越好，汽油发动机的压缩比也可以相应提高。令人遗憾的是，当初令美国人骄傲不已的“发明”，如今正成为全世界需要“通缉”的“无形杀手”。四乙基铅有剧烈的毒性，加入四乙基铅的汽油燃烧后，８５％左右的铅将直接排入大气中，造成严重的铅污染。四乙基铅含铅约６４％，主要通过呼吸道和皮肤侵入人体，也可通过食物链被胃肠道吸收，进入血液、软组织和矿…     

铅同位素在示踪城市环境污染源研究中的应用

在分析铅同位素示踪环境铅污染源理论的基础上,以成都市为例,对成都市城市环境（土壤、大气降尘、主要水系沉积物）铅污染的主要来源进行了研究.结果表明,成都市城市环境污染主要来自于燃煤扬尘和汽车尾气排放.铅同位素示踪理论应用于城市环境污染源的研究,能够取得比较理想的结果.     

High resolution gas chromatographic determination of the atmospheric reactivity of engine-out hydrocarbon emissions from a spark-ignited engine

The reactivities of engine-out exhaust hydrocarbon (HC) emissions in photochemical smog formation have been determined for three fuels (isooctane, an aromatic blend, and a gasoline) in a single-cylinder, spark-ignited engine. High resolution capillary GC was used to determine the mole fractions of the exhaust hydrocarbon species. Temperature programmed chromatography on a single capillary column was sufficient to separate the major exhaust species. A library of approximately 160 hydrocarbon species was used to identify typically 90–95 % of the HC species present. GC-MS was used selectively to verify peak assignments. The effect of engine operating parameters (fuel-to-air ratio, spark timing, and speed) on reactivity was examined. Engine operating parameters affect both total emissions [g/mile] and the specific atmospheric reactivity [g ozone/g HC emissions] of these emissions. Changing the operating parameters to control total emissions may not be as effective as expected in controlling the total reactivity [g ozone/mile] of the emissions because the specific reactivity can also change simultaneously. Effects of changes in operating parameters differ significantly as the type of fuel is varied. The ability to measure exhaust hydrocarbon species emissions accurately and quickly will increase in importance as reactivity-based emissions standards come into widespread use.     

Determination of alkyl lead compounds in air by gas chromatography and atomic absorption spectrometry

Alkyl lead compounds are condensed from a 70-l street air sample in a series of four traps at-72°C, separated by gas chromatography and determined by atomic absorption spectrometry with electrothermal atomization. Total atmospheric alkyl lead averaged 14 ng Pb m^-3. Vehicular exhaust fumes are an insignificant contributor to this total. Tetraethyllead, the only alkyl lead compound used in southern Ontario gasoline, is unstable in air. Besides decomposing, it reacts to give other alkyl lead compounds, which can be determined by the technique described. Evaporation of gasoline is almost exclusively the source of alkyl lead compounds in street air.     

Ethanol

Ethanol can be directly blended with gasoline, reacted with isobutylene to form the oxygenated fuel additive ethyl tert-butyl ether (ETBE), or burned directly as a neat fuel. Blends of either ethanol or ETBE with gasoline force engines set for gasoline to run lean and can substantially reduce carbon monoxide emissions. ETBE also lowers the overall vapor pressure, thereby cutting back on smog-forming emissions. Neat ethanol further reduces smog formation since it has a low volatility, the photochemical reactivity of ethanol and its combustion products is low, and low levels of smog producing compounds are formed by ethanol combustion. Neat ethanol also offers good engine performance owing to its high heat of vaporization, high octane, and low flame temperature. Fermentation stoichiometry reveals that many feedstocks are expensive for fuels production even considering coproduct credits and ignoring conversion costs, whereas lignocellulosic feedstocks cost much less than their value. Furthermore, the quantities of lignocellulosics are projected to be ample even for neat ethanol production. Release of carbon dioxide during fermentation concentrates almost all the heat of combustion from the solid carbohydrate portion in liquid ethanol. Since the carbon dioxide released during production and use of ethanol is recycled during growth of biomass, ethanol utilization doesn’t contribute to the accumulation of carbon dioxide in the atmosphere and possible global warming.     

分析测试新成果(230~237)2种常见燃油添加剂对汽油燃烧烟尘的影响

采用气相色谱-质谱(GC-MS)联用技术,根据汽油原样中的特征成分,对未加入和分别加入汽油燃油精、海龙燃油宝的汽油燃烧烟尘进行对比分析.结果表明,汽油燃油精的加入会使汽油燃烧烟尘中各类特征成分的百分含量有所变化,但对谱图和特征成分的影响较小;而海龙燃油宝的加入对汽油燃烧烟尘的谱图、特征成分及其个数、各类特征成分的百分含量均产生较大影响.结果为火灾物证鉴定提供一定的参考依据.     

Automotive fuels and internal combustion engines: a chemical perspective

Commercial transportation fuels are complex mixtures containing hundreds or thousands of chemical components, whose composition has evolved considerably during the past 100 years. In conjunction with concurrent engine advancements, automotive fuel composition has been fine-tuned to balance efficiency and power demands while minimizing emissions. Pollutant emissions from internal combustion engines (ICE), which arise from non-ideal combustion, have been dramatically reduced in the past four decades. Emissions depend both on the engine operating parameters (e.g. engine temperature, speed, load, A/F ratio, and spark timing) and the fuel. These emissions result from complex processes involving interactions between the fuel and engine parameters. Vehicle emissions are comprised of volatile organic compounds (VOCs), CO, nitrogen oxides (NO(x)), and particulate matter (PM). VOCs and NO(x) form photochemical smog in urban atmospheres, and CO and PM may have adverse health impacts. Engine hardware and operating conditions, after-treatment catalysts, and fuel composition all affect the amount and composition of emissions leaving the vehicle tailpipe. While engine and after-treatment effects are generally larger than fuel effects, engine and after-treatment hardware can require specific fuel properties. Consequently, the best prospects for achieving the highest efficiency and lowest emissions lie with optimizing the entire fuel-engine-after-treatment system. This review provides a chemical perspective on the production, combustion, and environmental aspects of automotive fuels. We hope this review will be of interest to workers in the fields of chemical kinetics, fluid dynamics of reacting flows, atmospheric chemistry, automotive catalysts, fuel science, and governmental regulations.     

液相氧化羰基化合成碳酸二乙酯的新型催化体系CuCl/1,10-菲罗啉/N-甲咪唑

Diethyl carbonate (DEC) is one of the important green chemicals widely used for organic synthesis because of its various functional groups. DEC is a better octane blending fuel, and has more oxygen in the molecule than methyl tert-butyl ether (MTBE), 40.6% versus 18.2%, which reduces emissions from gasoline and diesel engine. For these reasons many studies on the production of DEC have been extensively carried out.