Center for Atmospheric Particle Studies, Carnegie Mellon University , Pittsburgh, Pennsylvania 15289, United States.
Environ Sci Technol. 2013 Aug 6;47(15):8288-96. doi: 10.1021/es400782j. Epub 2013 Jul 10.
Experiments were performed to investigate the gas-particle partitioning of primary organic aerosol (POA) emissions from two medium-duty (MDDV) and three heavy-duty (HDDV) diesel vehicles. Each test was conducted on a chassis dynamometer with the entire exhaust sampled into a constant volume sampler (CVS). The vehicles were operated over a range of driving cycles (transient, high-speed, creep/idle) on different ultralow sulfur diesel fuels with varying aromatic content. Four independent yet complementary approaches were used to investigate POA gas-particle partitioning: artifact correction of quartz filter samples, dilution from the CVS into a portable environmental chamber, heating in a thermodenuder, and thermal desorption/gas chromatography/mass spectrometry (TD-GC-MS) analysis of quartz filter samples. During tests of vehicles not equipped with diesel particulate filters (DPF), POA concentrations inside the CVS were a factor of 10 greater than ambient levels, which created large and systematic partitioning biases in the emissions data. For low-emitting DPF-equipped vehicles, as much as 90% of the POA collected on a quartz filter from the CVS were adsorbed vapors. Although the POA emission factors varied by more than an order of magnitude across the set of test vehicles, the measured gas-particle partitioning of all emissions can be predicted using a single volatility distribution derived from TD-GC-MS analysis of quartz filters. This distribution is designed to be applied directly to quartz filter data that are the basis for existing emissions inventories and chemical transport models that have implemented the volatility basis set approach.
进行了实验来研究两种中型（MDDV）和三种重型（HDDV）柴油车的一次有机气溶胶（POA）排放的气粒分配。每个测试都是在底盘测功机上进行的，整个排气都被采样到一个恒容采样器（CVS）中。这些车辆在不同超低硫柴油燃料上进行了一系列驾驶循环（瞬态、高速、爬行/怠速），这些燃料具有不同的芳烃含量。采用了四种独立但互补的方法来研究 POA 气粒分配：对石英滤膜样品进行人工制品校正、从 CVS 稀释到便携式环境室、在热沉降器中加热，以及对石英滤膜样品进行热解吸/气相色谱/质谱（TD-GC-MS）分析。在未配备柴油颗粒过滤器（DPF）的车辆测试中，CVS 内的 POA 浓度比环境水平高 10 倍，这在排放数据中造成了大而系统的分配偏差。对于低排放的配备 DPF 的车辆，从 CVS 上的石英滤膜上收集的 POA 中多达 90%是吸附的蒸气。尽管 POA 排放因子在一组测试车辆中变化超过一个数量级，但使用从石英滤膜的 TD-GC-MS 分析得出的单一挥发性分布可以预测所有排放的测量气粒分配。该分布旨在直接应用于石英滤膜数据，这些数据是现有排放清单和已实施挥发性基础集方法的化学传输模型的基础。
