Mechanical and Aerospace Department, West Virginia University , Morgantown, 395 Evansdale Drive, P.O. Box 6106, West Virginia 26505, United States.
Environ Sci Technol. 2014 Jul 15;48(14):8235-42. doi: 10.1021/es5005973. Epub 2014 Jul 3.
Experiments were conducted to characterize the particulate matter (PM)-size distribution, number concentration, and chemical composition emitted from transit buses powered by a USEPA 2010 compliant, stoichiometric heavy-duty natural gas engine equipped with a three-way catalyst (TWC). Results of the particle-size distribution showed a predominant nucleation mode centered close to 10 nm. PM mass in the size range of 6.04 to 25.5 nm correlated strongly with mass of lubrication-oil-derived elemental species detected in the gravimetric PM sample. Results from oil analysis indicated an elemental composition that was similar to that detected in the PM samples. The source of elemental species in the oil sample can be attributed to additives and engine wear. Chemical speciation of particulate matter (PM) showed that lubrication-oil-based additives and wear metals were a major fraction of the PM mass emitted from the buses. The results of the study indicate the possible existence of nanoparticles below 25 nm formed as a result of lubrication oil passage through the combustion chamber. Furthermore, the results of oxidative stress (OS) analysis on the PM samples indicated strong correlations with both the PM mass calculated in the nanoparticle-size bin and the mass of elemental species that can be linked to lubrication oil as the source.
进行了实验以描述颗粒物（PM）大小分布、数量浓度和化学成分，这些颗粒物是由符合美国环保署 2010 年标准的、化学计量的重型天然气发动机排放的，该发动机配备了三效催化剂（TWC）。颗粒物大小分布的结果显示，主要的成核模态集中在接近 10nm 的位置。6.04 至 25.5nm 范围内的 PM 质量与在重量 PM 样品中检测到的润滑衍生元素物种的质量密切相关。油分析的结果表明，元素组成与 PM 样品中检测到的相似。油样中元素物种的来源可归因于添加剂和发动机磨损。颗粒物的化学形态表明，基于润滑油的添加剂和磨损金属是从公共汽车排放的 PM 质量的主要部分。研究结果表明，由于润滑油通过燃烧室，可能存在 25nm 以下的纳米颗粒。此外，对 PM 样品进行的氧化应激（OS）分析的结果表明，与在纳米颗粒大小箱中计算的 PM 质量以及与润滑油来源相关的元素物种的质量之间存在很强的相关性。
