...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Atmospheric chemistry and physics >Overview of VOC emissions and chemistry from PTR-TOF-MS measurements during the SusKat-ABC campaign: high acetaldehyde, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley
【24h】

Overview of VOC emissions and chemistry from PTR-TOF-MS measurements during the SusKat-ABC campaign: high acetaldehyde, isoprene and isocyanic acid in wintertime air of the Kathmandu Valley

机译：SusKat-ABC活动期间通过PTR-TOF-MS测量获得的VOC排放和化学概述：加德满都谷地冬季空气中的高乙醛，异戊二烯和异氰酸

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The Kathmandu Valley in Nepal suffers from severe wintertime air pollution. Volatile organic compounds (VOCs) are key constituents of air pollution, though their specific role in the valley is poorly understood due to insufficient data. During the SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley-Atmospheric Brown Clouds) field campaign conducted in Nepal in the winter of 2012-2013, a comprehensive study was carried out to characterise the chemical composition of ambient Kathmandu air, including the determination of speciated VOCs, by deploying a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) - the first such deployment in South Asia. In the study, 71 ion peaks (for which measured ambient concentrations exceeded the 2 sigma detection limit) were detected in the PTR-TOF-MS mass scan data, highlighting the chemical complexity of ambient air in the valley. Of the 71 species, 37 were found to have campaign average concentrations greater than 200 ppt and were identified based on their spectral characteristics, ambient diel profiles and correlation with specific emission tracers as a result of the high mass resolution (maEuro-a center dot aEuro-Delta maEuro-aEuro parts per thousand > aEuro-4200) and temporal resolution (1aEuro-min) of the PTR-TOF-MS. The concentration ranking in the average VOC mixing ratios during our wintertime deployment was acetaldehyde (8.8 ppb) > methanol (7.4 ppb) > acetone + propanal (4.2 ppb) > benzene (2.7 ppb) > toluene (1.5 ppb) > isoprene (1.1 ppb) > acetonitrile (1.1 ppb) > C8-aromatics ( aEuro parts per thousand 1 ppb) > furan ( aEuro parts per thousand 0.5 ppb)aEuro-aEuro parts per thousand > aEuro-C9-aromatics (0.4 ppb). Distinct diel profiles were observed for the nominal isobaric compounds isoprene (maEuro-a center dot aEuro-zaEuro-aEuro parts per thousand= aEuro-69.070) and furan (maEuro-a center dot aEuro-zaEuro-aEuro parts per thousand= aEuro-69.033). Comparison with wintertime measurements from several locations elsewhere in the world showed mixing ratios of acetaldehyde ( aEuro parts per thousand aEuro-9 ppb), acetonitrile ( aEuro parts per thousand aEuro-1 ppb) and isoprene ( aEuro parts per thousand aEuro-1 ppb) to be among the highest reported to date. Two 'new' ambient compounds, namely formamide (maEuro-a center dot aEuro-zaEuro-aEuro parts per thousand= aEuro-46.029) and acetamide (maEuro-a center dot aEuro-zaEuro-aEuro parts per thousand= aEuro-60.051), which can photochemically produce isocyanic acid in the atmosphere, are reported in this study along with nitromethane (a tracer for diesel exhaust), which has only recently been detected in ambient studies. Two distinct periods were selected during the campaign for detailed analysis: the first was associated with high wintertime emissions of biogenic isoprene and the second with elevated levels of ambient acetonitrile, benzene and isocyanic acid from biomass burning activities. Emissions from biomass burning and biomass co-fired brick kilns were found to be the dominant sources for compounds such as propyne, propene, benzene and propanenitrile, which correlated strongly with acetonitrile (r(2) > 0.7), a chemical tracer for biomass burning. The calculated total VOC OH reactivity was dominated by acetaldehyde (24.0 %), isoprene (20.2 %) and propene (18.7 %), while oxygenated VOCs and isoprene collectively contributed to more than 68 % of the total ozone production potential.
机译：尼泊尔的加德满都谷地冬季空气污染严重。挥发性有机化合物（VOC）是空气污染的关键成分，尽管由于数据不足，人们对其在山谷中的具体作用了解甚少。在2012-2013年冬季在尼泊尔进行的SusKat-ABC（加德满都谷地可持续大气-棕褐色云）野外活动期间，进行了一项全面研究，以表征加德满都周围空气的化学成分，包括确定通过部署质子转移反应飞行时间质谱仪（PTR-TOF-MS）来确定特定的VOC，这是南亚的首个此类部署。在这项研究中，在PTR-TOF-MS质量扫描数据中检测到71个离子峰（其测量的环境浓度超过2 sigma检测极限），突出了山谷中环境空气的化学复杂性。在71种中，发现37种的平均运动浓度大于200 ppt，并根据其光谱特征，环境diel轮廓以及由于高质量分辨率而与特定排放示踪剂的相关性进行鉴定（maEuro-a点aEuro -PTR-TOF-MS的Delta千欧元欧元/千欧元部分> aEuro-4200）和时间分辨率（1aEuro-min）。在冬季部署期间，平均VOC混合比中的浓度排名为乙醛（8.8 ppb）>甲醇（7.4 ppb）>丙酮+丙醛（4.2 ppb）>苯（2.7 ppb）>甲苯（1.5 ppb）>异戊二烯（1.1 ppb） ）>乙腈（1.1 ppb）> C8-芳族化合物（千分之一欧元）>呋喃（千分之0.5欧元分欧元）一千分欧元-欧元>九烷基芳烃（0.4 ppb）。对于标称同量异戊二烯化合物异戊二烯（maEuro-a中心点aEuro-zaEuro-aEuro千分之一= aEuro-69.070）和呋喃（maEuro-a中心点aEuro-zaEuro-aEuro千分之一= aEuro-69.033）观察到不同的diel分布）。与世界各地其他地方的冬季测量值进行比较，结果显示乙醛（aEuro千分之一的aEuro-9 ppb），乙腈（aEuro千分之一的aEuro-1 ppb）和异戊二烯（aEuro千分之一的aEuro-1 ppb）的混合比是迄今为止报道次数最多的。两种“新的”环境化合物，即甲酰胺（maEuro-a中心点aEuro-zaEuro-aEuro千分之一= aEuro-46.029）和乙酰胺（maEuro-a中心点aEuro-zaEuro-aEuro千分之一= aEuro-60.051），这项研究报告了可在大气中以光化学方式产生异氰酸的化合物以及硝基甲烷（一种用于柴油机废气的示踪剂），而硝基甲烷直到最近才在环境研究中被发现。在竞选期间选择了两个不同的时期进行详细分析：第一个时期与冬季生物源异戊二烯的高排放量有关，第二个时期与生物质燃烧活动中环境乙腈，苯和异氰酸的水平升高有关。生物质燃烧和生物质共烧砖窑的排放被发现是丙炔，丙烯，苯和丙腈等化合物的主要来源，它们与乙腈（r（2）> 0.7）密切相关，乙腈是生物质燃烧的化学示踪剂。计算出的总VOC OH反应性主要由乙醛（24.0％），异戊二烯（20.2％）和丙烯（18.7％）决定，而含氧的VOC和异戊二烯合计占总臭氧生产潜力的68％以上。

著录项

相似文献

  • 外文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号