Abstract：
Ammonia, a significant precursor for secondary inorganic aerosols, plays a pivotal role in new particle formation. Inventories and source apportionment studies have identified vehicular exhaust as a primary source of atmospheric ammonia in urban regions. Existing research on the factors influencing ammonia emissions from gasoline vehicles exhibits substantial inconsistencies in both test results and analyses. The lack of a uniform pattern in ammonia emissions across different standard vehicles and the significant overlap in test results across diverse operational conditions highlight the complexities in this field of study. While individual results can be interpreted through a mechanistic lens, disparate studies often lack a common explanatory framework. To address this gap, our study leverages the robust and comprehensive approach of meta-analysis to reconcile these inconsistencies and provide a more precise understanding of the factors influencing ammonia emissions from gasoline vehicles. A large number (N = 537) of ammonia emission factors were extracted after screening >1628 publications. The combined ammonia emission factor was 23.57 ± 24.94 mg/km. Emission standards, engine type, ambient temperatures, mileage, vehicle speed, and engine displacement have a significant impact on ammonia emission factors, explaining the ammonia emission factor by up to 50.63 %, with speed being the most significant factor. All these factors are attributed to the interplay of catalyst properties, lambda, and residence time (space velocity). In the current fleet, ammonia emission control is relatively insufficient under low-speed and ultra-high speed, low temperature, and ultra-high mileage conditions. Since ammonia emission factors do not monotonically decrease with the upgrading of motor vehicle emission standards, it is called for the addition of ammonia emission factors indicators in motor vehicle emission standards, and stipulation of targeted testing procedures and testing instruments.
摘要：
氨,二次无机气溶胶的重要前兆，在新粒子的形成中起着关键作用。清单和来源分配研究已将汽车尾气确定为城市地区大气氨的主要来源。对影响汽油车氨排放的因素的现有研究在测试结果和分析中都表现出很大的不一致。不同标准车辆的氨排放缺乏统一的模式，以及不同运行条件下测试结果的显著重叠，突出了这一研究领域的复杂性。虽然个体结果可以通过机械透镜来解释，不同的研究往往缺乏一个共同的解释框架。为了解决这个差距，我们的研究利用了稳健而全面的荟萃分析方法来调和这些不一致之处,并更准确地了解了影响汽油车氨排放的因素.筛选>1628篇出版物后，提取了大量（N=537）氨排放因子。综合氨排放因子为23.57±24.94mg/km。排放标准,发动机类型,环境温度,里程,车速,和发动机排量对氨排放因素有显著影响，解释氨排放因子高达50.63%，速度是最重要的因素。所有这些因素都归因于催化剂性能的相互作用，lambda,和停留时间（空速）。在目前的舰队中,在低速和超高速下，氨排放控制相对不足，低温,和超高里程条件。由于氨排放因子不会随着机动车排放标准的提高而单调下降,呼吁在机动车排放标准中增加氨排放因子指标，并规定有针对性的测试程序和测试仪器。
