Department of Chemistry and Molecular Biology, Atmospheric Science , University of Gothenburg , SE-412 96 Gothenburg , Sweden.
IVL Swedish Environmental Research Institute , Box 530 21, SE-400 14 Gothenburg , Sweden.
Environ Sci Technol. 2018 Jul 17;52(14):7720-7728. doi: 10.1021/acs.est.8b01394. Epub 2018 Jun 26.
The potential effect of changing to a nonfossil fuel vehicle fleet was investigated by measuring primary emissions (by extractive sampling of bus plumes) and secondary mass formation, using a Gothenburg Potential Aerosol Mass (Go:PAM) reactor, from 29 in-use transit buses. Regarding fresh emissions, diesel (DSL) buses without a diesel particulate filter (DPF) emitted the highest median mass of particles, whereas compressed natural gas (CNG) buses emitted the lowest (EF 514 and 11 mg kg, respectively). Rapeseed methyl ester (RME) buses showed smaller EF and particle sizes than DSL buses. DSL (no DPF) and hybrid-electric RME (RME) buses exhibited the highest particle numbers (EF 12 × 10 # kg). RME buses displayed a significant nucleation mode ( D< 20 nm). EF of CNG buses spanned the highest to lowest values measured. Low EF and EF were observed for a DPF-equipped DSL bus. Secondary particle formation resulting from exhaust aging was generally important for all the buses (79% showed an average EF/EF ratio >10) and fuel types tested, suggesting an important nonfuel dependent source. The results suggest that the potential for forming secondary mass should be considered in future fuel shifts, since the environmental impact is different when only considering the primary emissions.
通过从 29 辆在用车中提取公共汽车尾气进行萃取采样，使用哥德堡潜在气溶胶质量（Go:PAM）反应器，研究了转换为非化石燃料车队的潜在影响，测量了一次排放和二次质量形成。关于新鲜排放，没有柴油颗粒过滤器（DPF）的柴油（DSL）公共汽车排放的颗粒质量最高中位数，而压缩天然气（CNG）公共汽车排放的颗粒质量最低（EF 分别为 514 和 11mg kg）。菜籽油甲酯（RME）公共汽车的 EF 和颗粒尺寸小于 DSL 公共汽车。DSL（无 DPF）和混合电动 RME（RME）公共汽车显示出最高的颗粒数（EF 12×10#kg）。RME 公共汽车显示出明显的成核模式（D<20nm）。CNG 公共汽车的 EF 跨度涵盖了测量到的最高和最低值。装有 DPF 的 DSL 公共汽车的 EF 较低。排气老化导致的二次颗粒形成对于所有测试的公共汽车（79%的平均 EF/EF 比值>10）和燃料类型通常都很重要，这表明存在重要的非燃料依赖源。结果表明，在未来的燃料转换中，应考虑形成二次质量的潜力，因为仅考虑一次排放时，环境影响是不同的。
