在用轻型汽油车尾气超标现状调查分析及治理措施

对郑州汽车尾气排放量所占份额较大的在用轻型汽油车进行较长时间的调查，将不同产地，车型，厂牌的汽车尾气超标状况进行了排序，同时对超标的原因进行了分析提出了治理措施与对策。     

炭黑工业尾气净化及余热利用

研究表明，炭黑工业生产过程尾气中的可燃气态污染物ＣＯ、Ｈ２、及ＣＨ４等，采用直接燃烧法，是目前我国炭黑尾气净化和回收利用的最佳控制方法。直接燃烧法，不仅可将尾气中可燃气态污染物转变为ＣＯ２和Ｈ２Ｏ，且可回收利用其热量，余热利用率可提高４０％以上。经济技术评价表明，采用直接燃烧法和炭黑尾气发电，其经济效益和环境效益十分可观。     

Mass spectral chemical fingerprints reveal the molecular dependence of exhaust particulate matters on engine speeds

Particulate matters(PMs) emitted by automobile exhaust contribute to a significant fraction of the global PMs. Extractive atmospheric pressure chemical ionization mass spectrometry(EAPCI-MS) was developed to explore the molecular dependence of PMs collected from exhaust gases produced at different vehicle engine speeds. The mass spectral fingerprints of the organic compounds embedded in differentially sized PMs(e.g., 0.22–0.45, 0.45–1.00, 1.00–2.00, 2.00–3.00, 3.00–5.00, and 5.00–10.00 μm) generated at different engine speeds(e.g., 1000, 1500, 2000, 2500, and 3000 r/min) were chemically profiled in the mass range of mass to charge ratio(m/z) 50–800. Organic compounds,including alcohols, aldehydes, and esters, were detected in all the PMs tested, with varied concentration levels for each individual PM sample. At relatively low engine speeds(≤ 1500 r/min), the total amount of organic species embedded in PMs of 0.22–1.00 μm was greater than in PMs of other sizes, while more organic species were found in PMs of5.00–10.00 μm at high engine speeds(≥ 3000 r/min), indicating that the organic compounds distributed in different sizes of PMs strongly correlated with the engine speed. The experimental data showed that the EAPCI-MS technique enables molecular characterization of PMs in exhaust, revealing the chemical dependence of PMs on the engine speeds(i.e., the combustion conditions) of automobiles.     

Studies on reactions of ozone with alkenes

In the last years, a continuous increase of the O3 concentration has been recorded in the lower atmospheric layers. Photochemical reactions with NO(x), CO and organic compounds are the main sources of O3 in the troposphere. In this work, an attempt was made to determine the impact of alkenes on the O3 concentration in the troposphere. A study on the gas-phase reactions of 03 with 1-hexene, 1-heptene and 1-nonene was made. The reactions were carried out at room temperature under atmospheric pressure. Ozone was formed by the ultraviolet radiation emitted by a mercury lamp, in order to simulate the atmospheric conditions. The changes with time in the concentration of O3, 1-alkenes and formed aldehydes were investigated. Qualitative and quantitative analyses were done by means of the gas chromatography and colorimetry. The following products were identified: pentanal from 1-hexene; hexanal from 1-heptene; oktanal from 1-nonene. For each of the reactions, HCHO was also determined as a product. The reaction rate constants were calculated and obtained in units of 10(-17) cm(-3) molecule(-1) s(-1): 1.94-0.99 for 1-hexene, 5.54-4.51 for 1-heptene and 1.54-0.76 for 1-nonene. Based on the results obtained, an explanation of O3 concentration variations in the planetary boundary layer can be given. Last year a considerable increase of O3 concentration on the roads of Western Europe was recorded. This increase could have resulted from the decrease of alkene concentration in the air due to common use of the catalytic converters in cars. The unsaturated hydrocarbons rapidly oxidize on the catalyst. In Eastern Europe, where the amount of cars equipped with catalytic converters is smaller than in Western Europe, the alkene content in the exhaust fumes results in a decrease of the O3 concentration in the troposphere.     

Monitoring atmospheric nitrous oxide background concentrations at Zhongshan Station, east Antarctica

At present,continuous observation data for atmospheric nitrous oxide(N_2O) concentrations are still lacking,especially in east Antarctica.In this paper,nitrous oxide background concentrations were measured at Zhongshan Station(69°22′25″S,76°22′14″E),east Antarctica during the period of 2008–2012,and their interannual and seasonal characteristics were analyzed and discussed.The mean N_2O concentration was 321.9 n L/L with the range of 320.5–324.8 n L/L during the five years,and it has been increasing at a rate of 0.29% year-1.Atmospheric N_2O concentrations showed a strong seasonal fluctuation during these five years.The concentrations appeared to follow a downtrend from spring to autumn,and then increased in winter.Generally the highest concentrations occurred in spring.This trend was very similar to that observed at other global observation sites.The overall N_2O concentration at the selected global sites showed an increasing annual trend,and the mean N_2O concentration in the Northern Hemisphere was slightly higher than that in the Southern Hemisphere.Our result could be representative of atmospheric N_2O background levels at the global scale.This study provided valuable data for atmospheric N_2O concentrations in east Antarctica,which is important to study on the relationships between N2 O emissions and climate change.     

Simple removal of dioxins by injecting combustion gas into water

A simple, low-cost method for suppression of dioxins/furans (hereinafter referred to as dioxins) is required because many middle- and, especially, small-scale incinerators have fallen into disuse or have been dismantled because of the high running and system costs of measures for the suppression of dioxins. Therefore, the purpose of the present study was to develop a simple removal method for dioxins from combustion gas and to evaluate the basic removal rate of dioxins. The removal method for suspended matter in a gas mixture (cold model) and dioxins in exhaust gases (hot model) has been investigated by means of gas injection into water, the mechanism of which is that the suspended matter in the gas gathers at the gas–liquid interface. In the cold model, the removal ratio of fine particles (R_P) by gas injection into water was reproduced well by the following equation: R_P (%) = 100 × {1−exp(−0.8 · S_S · t_C)}, where S_S (cm²/cm³) is the specific surface area of bubbles and t_C (s) is the residence time of bubbles in water. The removal ratio of fine particles increased as the product S_s · t_C increased. In a hot model using the exhaust gas from combustion experiments of polyvinyl chloride, the removal ratio of dioxins (R_D) by injecting the exhaust gas into water was estimated by the following equation: R_D (%) = 100 × {1−exp(−0.8 · S_S · t_C · C_D0 ^0.07)}, where C_D0 [ng/cm³ (at standard temperature and pressure)] is the dioxins concentration in the exhaust gas before injection into water. R_D depends greatly on the specific surface area of bubbles and the residence time of the bubbles in water, and only weakly on the dioxins concentration in the exhaust gas. Injection of the exhaust gas into water has been shown to be effective and was evaluated as a simple method for the removal of dioxins from exhaust gas.     

气相色谱法分析环境空气和废气中正丁醇

以纯净水吸收环境空气或工业废气中的正丁醇,用Rtx-WAX毛细管柱分离,氢火焰离子化检测器检测,吹扫捕集后进气相色谱仪测定。方法最低检出量浓度正丁醇0.005mg/m3,相对标准偏差在1%以下,加标回收率在85.8%～93.00%之间,方法安全环保,简单灵敏,分离度好,检出限低。     

地下停车场车辆尾气排放污染物的预测与评价

随着机动车数量不断增长,车辆尾气排放对人们的影响也在加剧,本文以沈阳市某住宅小区地下停车场的车辆尾气排放实测数据与环评工作中常用的经验预测公式进行比较,分析计算尾气污染物的各预测公式的准确程度;同时,对预测值进行评价时,采用不同空气质量标准得出的达标结论有所不同,以此比较不同标准的适用性,为该类项目的环评提供参考。     

汽车尾气中NO_X再燃烧过程的动力学

为了阐明汽车尾气中 NOX再燃烧的动力学进程 ,以甲醛和 NO2 作为探针分子 ,通过 FT-IR跟踪研究了反应体系中所产生的 HCO自由基与 NO2 反应的动力学。结果表明 ,反应的主要产物中包括 CO、CO2 、NO、HONO和 H2 O等分子 ,经长时间的反应 ,当体系中的 NO2 基本耗尽时 ,才有少量的 N2 O生成。这些产物分子分别是在几个不同途径的连串反应中形成的。从体系中 CO和 CO2 的生成量 ,测定了主反应的歧化反应速率比 ,并对相应的动力学机理进行了讨论。     

关于机动车尾气检测方法及污染防治措施研究

机动车尾气成分中包含着许多种类的化合物,而绝大多数化合物不仅威胁人体健康而且极易造成空气污染。现阶段,我国机动车尾气排放特征为排放量大、短期、局部污染极为严重与集中排放等,对此我国应提高对机动车尾气检测问题的重视程度,并采取相应的措施防治机动车尾气排放。基于此,文章简要分析机动车尾气的有关检测方法及其防治路径。