Hydroxyl, hydroperoxyl free radicals determination methods in atmosphere and troposphere

The hydroxyl radical (?OH) has a crucial function in the oxidation and removal of many atmospheric compounds that are harmful to health. Nevertheless, high reactivity, low atmospheric abundance, determination of hydroxyl, and hydroperoxyl radical's quantity is very difficult. In the atmosphere and troposphere, hydroperoxyl radicals (HO₂) are closely demanded in the chemical oxidation of the troposphere. But advances in technology have allowed researchers to improve the determination methods on the research of free radicals through some spectroscopic techniques. So far, several methods such as laser-induced fluorescence (LIF), high-performance liquid chromatography (HPLC), and chemical ionization mass spectroscopy have been identified and mostly used in determining the quantity of hydroxyl and hydroperoxyl radicals. In this systematic review, we have advised the use of scavenger as an advance for further researchers to circumvent some of these problems caused by free radicals. The primary goal of this review is to deepen our understanding of the functions of the most critical free radical (?OH, HO₂) and also understand the currently used methods to quantify them in the atmosphere and troposphere.     

城市河道水质评价与研究

结合内梅罗指数法的原理,考虑金属毒性的积累效应,引入污染因子权重值,将权重值最大的评价指标纳入计算,采用改进的内梅罗指数法评价城市河道的水质污染状况。并对水质的划分标准临界值进行计算,以此作为评价水质污染状况的依据。研究结果表明,两种方法具有明显的差异,改进的内梅罗指数法对水质污染状况的评价结果较传统内梅罗指数法的辨识度更高,能够综合客观全面地体现城市河道水质状况,与真实情况较好的吻合,更为客观、合理。     

生活垃圾填埋场封场后种植植物中重金属迁移研究

在上海老港生活垃圾填埋场填埋单元封场的覆盖土中掺混了矿化垃圾种植植物,分析Cd、Pb、Cu、Zn 4种重金属在土壤和植物中的迁移变化,研究表明:(1)覆盖土土质从一般耕作土变成肥沃土壤;覆盖土和种植混合土重金属Cd、Pb、Cu、Zn中Cd、Pb含量相近,但种植土的Cu含量略大于覆盖原土,Zn含量远大于覆盖原土;(2)植物能富集土壤和垃圾中的重金属,木本植物的根部富集重金属的能力强于草本植物,但重金属在草本植物根、茎、叶中的迁移速度大于木本植物;(3)植物根、茎、叶的Cu、Zn含量均远大于未受污染土壤种植植物相应部位的Cu、Zn含量,种植的植物不能供家养动物食用,以免通过食物链作用危及人体安全.     

荧光化学传感器的制备及其在环境分析监测中的应用

随着荧光分析技术和传感技术的发展,荧光化学传感器已经成为一种重要的连续分析测量装置.它具有很高的选择性和灵敏度,可以实现对pH、溶解氧、含氮化合物、有毒害重金属离子、有机污染物进行实时和在线测定,因此在环境分析监测方面具有广泛的应用前景.简要介绍了荧光化学传感器的原理、制备及分类,综述了近年来荧光化学传感器的发展及其在环境分析监测中的最新研究成果,并探讨了荧光化学传感器在环境分析监测领域的应用前景和发展方向.     

隔声屏障在冷却机组降噪中的设计与应用实证

本文对成都双流九江环保垃圾发电厂循环冷却机组进行噪声治理,通过在声音传播途径上设立隔声屏障,并对该声屏障进行声学设计理论计算,声屏障建成后该机组在厂界外1m处,噪声值达到国家厂界噪声排放标准要求,并通过详细的实测数据、建立图形,进一步验证了声屏障理论计算公式和保护范围。     

Potential of secondary aerosol formation from Chinese gasoline engine exhaust

Light-duty gasoline vehicles have drawn public attention in China due to their significant primary emissions of particulate matter and volatile organic compounds(VOCs). However,little information on secondary aerosol formation from exhaust for Chinese vehicles and fuel conditions is available. In this study, chamber experiments were conducted to quantify the potential of secondary aerosol formation from the exhaust of a port fuel injection gasoline engine. The engine and fuel used are common in the Chinese market, and the fuel satisfies the China V gasoline fuel standard. Substantial secondary aerosol formation was observed during a 4–5 hr simulation, which was estimated to represent more than 10 days of equivalent atmospheric photo-oxidation in Beijing. As a consequence, the extreme case secondary organic aerosol(SOA) production was 426 ± 85 mg/kg-fuel, with high levels of precursors and OH exposure. The low hygroscopicity of the aerosols formed inside the chamber suggests that SOA was the dominant chemical composition. Fourteen percent of SOA measured in the chamber experiments could be explained through the oxidation of speciated single-ring aromatics. Unspeciated precursors, such as intermediate-volatility organic compounds and semi-volatile organic compounds, might be significant for SOA formation from gasoline VOCs. We concluded that reductions of emissions of aerosol precursor gases from vehicles are essential to mediate pollution in China.     

基于环境保护的机动车税优化建议

当前区域性大气污染问题突出,机动车使用造成的污染问题不可忽视。为解决区域性的大气污染问题,机动车税费的污染减排调控功能日益被政府和学者重视。研究围绕"如何使机动车税更好发挥环境保护的效果"的问题,比较了中日机动车税的结构和性质,分析了在购买、保有和使用等不同环节的机动车税的特点以及环保效果,并基于问卷调查分析中国私家车主不同环节机动车税的负担情况。研究表明,在机动车使用环节征收的成品油消费税污染调控效果要优于其他环节的税收;对商业用途的机动车使用征税仅有收入功能没有调控功能,建议将机动车相关税的作用重心从购买环节转移到使用环节上,并对商业用途和私人用途的机动车实施差别税率。     

活性碳纤维改性技术研究进展

介绍了活性碳纤维(ACF)的孔结构及表面官能团,综述了国内外ACF改性技术的研究现状.ACF的改性主要包括孔结构调控和表面化学改性,表面化学改性包括氧化还原法、表面负载法、浸渍法、热处理法、远程等离子体处理法、微波辐照法等,也可将多种方法结合来对ACF进行改性,以改善和提高ACF的吸附性能.在总结现有研究的基础上,对ACF改性技术发展趋势进行了展望.     

A red water occurrence in drinking water distribution systems caused by changes in water source in Beijing,China: mechanism analysis and control measures

A red water phenomenon occurred in several communities few days after the change of water source in Beijing, China in 2008. In this study, the origin of this problem, the mechanism of iron release and various control measures were investigated. The results indicated that a significant increase in sulphate concentration as a result of the new water source was the cause of the red water phenomenon. The mechanism of iron release was found that the high-concentration sulphate in the new water source disrupted the stable shell of scale on the inner pipe and led to the release of iron compounds. Experiments showed that the iron release rate in the new source water within pipe section was over 11-fold higher than that occurring within the local source water. The recovery of tap water quality lasted several months despite ameliora- tive measures being implemented, including adding phosphate, reducing the overall proportion of the new water source, elevating the pH and alkalinity, and utilizing free chlorine as a disinfectant instead of chloramine. Adding phosphate was more effective and more practical than the other measures. The iron release rate was decreased after the addition of 1.5 mg. L-1 orthophosphate- P, tripolyphosphate-P and hexametaphosphate-P by 68%, 83% and 87%, respectively. Elevating the pH and alkalinity also reduced the iron release rate by 50%. However, the iron release rate did not decreased after replacing chloramine by 0.5-0.8 mg. L-1 of free chlorine as disinfectant.     

邯郸市新冠疫情前后空气质量指数(AQI)对比与疫情防控期间大气污染特征分析

2020年初COVID-19疫情爆发,我国采取一系列管控措施使大气污染物排放量明显降低.为了解疫情期间减排活动下邯郸市大气污染特征,采用统计学变量分析方法与特征雷达图对疫情爆发前(12月、1月)、疫情防控期间(2-4月)、疫情防控后(5月、6月)以及2019年同期大气污染情况进行对比分析.并进一步估算防控期间大气污染物的减排量,通过后向轨迹聚类分析气团的迁移轨迹来探讨人为减排对空气质量的影响.结果 表明,2020年2月疫情管控开始后,环境空气质量与2019年同期相比明显好转,2月份AQI值降幅约为50％,3、4月份两年差距逐渐缩小;疫情防控期间较疫情爆发前空气质量也有较大幅度提升,防控结束后AQI值有小幅度回弹;防控期间PM2.5、PM10、 SO2、NO2、CO的日平均浓度值均有较大幅度下降,在2月份下降最为明显,降幅分别为51％、55％、62％、41％、33％;O38 h平均浓度与气温呈显著正相关(0.747),疫情期间浓度呈上升趋势,在4月底达到的峰值(238 μg·m-3).北京市空气污染相对较轻,邯郸市与石家庄市较为严重,整体上受颗粒物的污染较明显.邯郸市2、3、4月份特征雷达图属于偏综合型,2月燃煤、生物质燃烧排放的污染物偏高,4月份来自工厂的NO2和SO2浓度偏高.疫情防控前期各污染物排放量均有较大幅度降低,与2019年2月的气团移动轨迹来源特征相似,说明人为减排对环境空气质量提升效果显著.