Environ Sci Technol. 2015 Apr 21;49(8):5178-88. doi: 10.1021/es505912b. Epub 2015 Mar 31.
A fuel-based approach is used to assess long-term trends (1970-2010) in mobile source emissions of black carbon (BC) and organic aerosol (OA, including both primary emissions and secondary formation). The main focus of this analysis is the Los Angeles Basin, where a long record of measurements is available to infer trends in ambient concentrations of BC and organic carbon (OC), with OC used here as a proxy for OA. Mobile source emissions and ambient concentrations have decreased similarly, reflecting the importance of on- and off-road engines as sources of BC and OA in urban areas. In 1970, the on-road sector accounted for ∼90% of total mobile source emissions of BC and OA (primary + secondary). Over time, as on-road engine emissions have been controlled, the relative importance of off-road sources has grown. By 2010, off-road engines were estimated to account for 37 ± 20% and 45 ± 16% of total mobile source contributions to BC and OA, respectively, in the Los Angeles area. This study highlights both the success of efforts to control on-road emission sources, and the importance of considering off-road engine and other VOC source contributions when assessing long-term emission and ambient air quality trends.
采用基于燃料的方法来评估移动源黑碳（BC）和有机气溶胶（OA，包括一次排放和二次形成）的长期趋势（1970-2010 年）。本分析的主要重点是洛杉矶盆地，在那里有长期的测量记录可用于推断 BC 和有机碳（OC）的环境浓度趋势，这里 OC 用作 OA 的替代物。移动源排放和环境浓度的下降趋势相似，反映了在道路上和道路外的发动机作为 BC 和 OA 在城市地区的来源的重要性。1970 年，道路上的车辆占 BC 和 OA（一次排放+二次形成）的总移动源排放的约 90%。随着时间的推移，随着对道路上的发动机排放的控制，道路外来源的相对重要性也在增加。到 2010 年，据估计，在洛杉矶地区，道路外发动机分别占 BC 和 OA 的总移动源贡献的 37±20%和 45±16%。本研究强调了控制道路上的排放源的努力的成功，以及在评估长期排放和空气质量趋势时考虑道路外发动机和其他 VOC 源贡献的重要性。
