Department of Chemistry and Biochemistry, University of Denver , Denver, Colorado 80208, United States.
Environ Sci Technol. 2015 Sep 15;49(18):11234-40. doi: 10.1021/acs.est.5b02392. Epub 2015 Aug 31.
Repeated, fuel-specific, emission measurements in Denver (2005/2013), Los Angeles (LA) (2008/2013), and Tulsa (2005/2013) provide long-term trends in on-road reactive nitrogen emissions from three light-/medium-duty U.S. fleets. Reductions in oxides of nitrogen (NOx) emissions ranged from 21% in Denver (from 5.6 ± 1.3 to 4.4 ± 0.2 g of NOx/kg of fuel) to 43% in Tulsa (from 4.4 ± 0.3 to 2.5 ± 0.1 g of NOx/kg of fuel) since 2005, while decreases in fleet ammonia (NH3) emissions ranged from no change in Denver (from 0.45 ± 0.09 to 0.44 ± 0.02 g of NH3/kg of fuel) since 2005 to a 28% decrease in LA (from 0.80 ± 0.02 to 0.58 ± 0.02 g of NH3/kg of fuel) since 2008. The majority of the reduction in gasoline vehicle NOx emissions occurred prior to the full implementation of the Tier II emission standards in 2009. High in-use NOx emissions from small-engine diesel passenger vehicles produced a significant contribution to the fleet means despite their small numbers. NH3 emissions decreased at a slower rate than NOx emissions as a result of modest NH3 emission reduction among the newest vehicles and increased emissions from a growing number of older vehicles with active catalytic converters. In addition, the reactive nitrogen emissions from many new model year vehicles are now dominated by NH3.
在丹佛（2005/2013 年）、洛杉矶（LA）（2008/2013 年）和塔尔萨（2005/2013 年）进行的重复、特定燃料的排放测量为来自美国三个轻型/中型车队的道路上活性氮排放提供了长期趋势。自 2005 年以来，氮氧化物（NOx）排放量的减少范围从丹佛的 21%（从 5.6±1.3 降至 4.4±0.2gNOx/kg 燃料）到塔尔萨的 43%（从 4.4±0.3 降至 2.5±0.1gNOx/kg 燃料），而车队氨（NH3）排放量的减少范围从丹佛的无变化（从 0.45±0.09 至 0.44±0.02gNH3/kg 燃料）到 LA 的 28%减少（从 0.80±0.02 至 0.58±0.02gNH3/kg 燃料）自 2008 年以来。在 2009 年全面实施 Tier II 排放标准之前，汽油车 NOx 排放量的大部分减少已经发生。尽管小排量柴油乘用车数量较少，但它们产生的高在用 NOx 排放对车队平均值的贡献仍然显著。由于最新车辆的 NH3 排放量略有减少，而装有活性催化转化器的越来越多的旧车辆的排放量增加，因此 NH3 排放量的减少速度低于 NOx 排放量。此外，许多新车型年车辆的活性氮排放量现在主要由 NH3 组成。
