2000～2020年天津市机动车全过程VOCs排放特征及演变

机动车排放已成为城市地区人为源挥发性有机物(VOCs)的重要来源，排放清单是量化其环境影响的重要手段.针对已有研究中存在的过程区分不清、排放因子测试不全和气象参数考虑不细等问题，基于文献调研与实验测试完善了排放因子库，在月尺度上提出了涵盖尾气排放和蒸发排放(包括运行损失、昼间排放、热浸排放和加油排放)的机动车全过程VOCs逐月排放清单构建方法，并应用此方法建立了2000～2020年天津市机动车全过程VOCs排放清单.研究期内，天津市机动车VOCs排放总量呈现出先缓慢上升后逐步下降的趋势，2020年排放总量为2.14万t,小型客车是对排放总量贡献最大的车型，贡献率达75.00%.排放标准升级对不同过程VOCs排放的影响存在差异.与尾气排放量的持续下降不同，蒸发排放量呈现出先升后降的倒U型走势，且对总排放量的贡献逐年上升，2020年时贡献率为31.69%.机动车排放的月度变化受活动水平与排放因子的双重影响.VOCs排放量呈现出秋冬季高和春夏季低的特点，2020年新冠疫情期间，封控措施限制了机动车活动水平，使得VOCs排放量显著低于往年同期.计算方法和数据结论可为大气污染防治工作提供技术参考...

Evolution and Characteristics of Full-process Vehicular VOCs Emissions in Tianjin from 2000 to 2020

Vehicle emissions are an important source of anthropogenic volatile organic compound (VOCs) emissions in urban areas and are commonly quantified using vehicle emission inventories. However, most previous studies on vehicle emission inventories have incomplete emission factors and emission processes or insufficient consideration of meteorological parameters. Based on the localized full-process emission factors attained from tested data and previous studies, a method to develop a monthly vehicular VOC emission inventory of full process for the long-term was established, which covered exhaust and evaporative emissions (including running loss, diurnal breathing loss, hot soak loss, and refueling emission). Then, the method was used to develop a full-process vehicular VOC emission inventory in Tianjin from 2000 to 2020. The results showed that the total vehicular VOC emissions in Tianjin rose slowly and then gradually decreased. In 2020, the total emissions were 21400 tons. The light-duty passenger vehicles were the dominant contributors and covered 75.00% of the total emissions. Unlike the continuous decline in exhaust emissions, evaporative emissions showed an inverted U-shaped trend with an increasing contribution to total emissions yearly, accounting for 31.69% in 2020. Monthly emissions were affected by both vehicle activity and emission factors. VOC emissions were high in autumn and winter and low in spring and summer. During the COVID-19 epidemic in 2020, vehicle activity was limited by closure and control, making VOC emissions significantly lower than those during the same period in previous years. The method and data in this study can provide technical reference and a decision-making basis for air pollution prevention and control.