Secondary organic aerosol origin in an urban environment: influence of biogenic and fuel combustion precursors.
Secondary organic aerosol origin in an urban environment: influence of biogenic and fuel combustion precursors.
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城市环境中的二次有机气溶胶起源：生物和燃料燃烧前体的影响。
作者：
M. Minguillón;Noemí Pérez;Nicolas Marchand;A. Bertrand;B. Temime;Konstantinos Agrios;S. Szidat;B. L. Drooge;Alexandre Sylvestre;A. Alastuey;C. Reche;A. Ripoll;Esther Marco;J. Grimalt;X. Querol
有机气溶胶（OA）的源贡献仍然没有完全理解，特别是在人为前体与自然前体形成的次生OA之间的定量区别。为了调查OA的起源，2013年夏天在巴塞罗那进行了一项实地活动，包括两个时期，其特征是低和高交通条件。挥发性有机化合物（VOC）的浓度较高，在第二个时期，特别是芳烃相关的交通排放，这表明了一个显着的每日周期峰值在交通高峰期，类似于黑碳（BC）的浓度。生物挥发性有机化合物（BVOC）的浓度只有轻微的变化，从低到高的交通期间，其日内的变化与温度和太阳辐射周期，虽然减少观察到单萜类化合物在白天。从第一阶段到第二阶段，有机碳（OC）浓度不断增加，非化石OC的比例由（14）C分析确定的总OC的43%增加到54%。结合（14）C分析和气溶胶化学形态监测（ACSM）OA源解析结果表明，除最后一个样品外，化石OC主要为次生OC（>70%），其次生OC仅占化石OC总量的51%。非化石次生有机碳的比例从第一个样品的37%增加到最后一个样品的60%。这种非化石次生氧化物（SOA）的形成增强可能归因于BVOC前体与道路交通排放的NOx（或其夜间衍生物硝酸盐，增强夜间半挥发性氧化物（SV-OOA））的反应，因为NO2浓度从第一个样品到最后一个样品从19 μg m（-3）增加到42 μg m（-3）。
Source contributions of organic aerosol (OA) are still not fully understood, especially in terms of quantitative distinction between secondary OA formed from anthropogenic precursors vs. that formed from natural precursors. In order to investigate the OA origin, a field campaign was carried out in Barcelona in summer 2013, including two periods characterized by low and high traffic conditions. Volatile organic compound (VOC) concentrations were higher during the second period, especially aromatic hydrocarbons related to traffic emissions, which showed a marked daily cycle peaking during traffic rush hours, similarly to black carbon (BC) concentrations. Biogenic VOC (BVOC) concentrations showed only minor changes from the low to the high traffic period, and their intra-day variability was related to temperature and solar radiation cycles, although a decrease was observed for monoterpenes during the day. The organic carbon (OC) concentrations increased from the first to the second period, and the fraction of non-fossil OC as determined by (14)C analysis increased from 43% to 54% of the total OC. The combination of (14)C analysis and Aerosol Chemical Speciation Monitor (ACSM) OA source apportionment showed that the fossil OC was mainly secondary (>70%) except for the last sample, when the fossil secondary OC only represented 51% of the total fossil OC. The fraction of non-fossil secondary OC increased from 37% of total secondary OC for the first sample to 60% for the last sample. This enhanced formation of non-fossil secondary OA (SOA) could be attributed to the reaction of BVOC precursors with NOx emitted from road traffic (or from its nocturnal derivative nitrate that enhances night-time semi-volatile oxygenated OA (SV-OOA)), since NO2 concentrations increased from 19 to 42 μg m(-3) from the first to the last sample.