Department of Civil and Environmental Engineering , University of California, Berkeley , Berkeley , California 94720 , United States.
Environmental Technologies Area , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
Environ Sci Technol. 2019 Dec 17;53(24):14568-14576. doi: 10.1021/acs.est.9b04763. Epub 2019 Dec 6.
Emissions from thousands of in-use heavy-duty diesel trucks were sampled at a highway and an arterial street location in the San Francisco Bay Area, spanning a time period when use of diesel particle filters (DPFs) and selective catalytic reduction (SCR) increased rapidly. At the highway site where a diverse mix of trucks is observed, SCR systems on 2010 and newer engines reduce emitted nitrogen oxides (NO) by 87 ± 5% relative to pre-2004 engines. SCR also mitigates DPF-related increases in nitrogen dioxide (NO) emissions. However, a majority of trucks had in-use NO emission rates that exceeded applicable emission standards. SCR systems increase emissions of nitrous oxide (NO) and ammonia (NH) from near-zero levels to 0.93 ± 0.13 and 0.18 ± 0.07 g kg, respectively. Emissions of all nitrogenous species and especially NH are skewed; 10% of trucks contribute 95% of the on-road fleet's total NH emissions. Similar emission changes are observed at the arterial street site where exclusively drayage trucks operate. The environmental effects of decreased black carbon, NO, and carbon dioxide (CO) emissions and increased NO and NH emissions due to the rapid adoption of DPF and SCR systems by the California truck fleet are: (1) a 65% net decrease in the social cost of statewide exposure to diesel truck emissions (-3.3 billion 2018 US dollars per year), and (2) a 3% net decrease in the global warming potential-weighted emission factor (-27 g CO-eq km).
在旧金山湾区的一条高速公路和一条主要街道上，对数千辆正在使用的重型柴油卡车的排放进行了采样，采样时间涵盖了柴油颗粒过滤器（DPF）和选择性催化还原（SCR）的使用迅速增加的时期。在高速公路现场观察到各种类型的卡车，2010 年及以后发动机上的 SCR 系统将排放的氮氧化物（NO）相对 2004 年前的发动机减少了 87±5%。SCR 还减轻了与 DPF 相关的二氧化氮（NO2）排放的增加。然而，大多数卡车的实际 NO 排放率超过了适用的排放标准。SCR 系统将一氧化二氮（N2O）和氨（NH3）的排放量从接近零水平增加到 0.93±0.13 和 0.18±0.07 g kg，分别。所有含氮物质的排放，尤其是 NH3 的排放都存在偏态分布；10%的卡车贡献了道路车队总 NH3 排放量的 95%。在专门从事拖运业务的主要街道现场也观察到类似的排放变化。由于加利福尼亚州卡车车队迅速采用 DPF 和 SCR 系统，减少了黑碳、NO 和二氧化碳（CO）的排放，增加了 NO 和 NH3 的排放，对环境的影响是：（1）全州范围内因柴油卡车排放而导致的暴露的社会成本净减少 65%（每年减少 33 亿美元），（2）加权全球变暖潜势排放因子的净减少 3%（每年减少 27 g CO-eq km）。
