Department of Civil and Environmental Engineering, University of California - Davis, Davis, CA, USA.
Department of Civil and Environmental Engineering, University of Southern California, Los Angeles, CA, USA.
Sci Total Environ. 2020 May 1;715:136902. doi: 10.1016/j.scitotenv.2020.136902. Epub 2020 Jan 23.
Ultrafine particles (UFPs) are an emerging air quality concern because of their enhanced toxicity compared to larger airborne particles. This study aims to better understand source contributions to UFP mass (PM) at multiples sites across California. Three-day average samples of PM collected over a full year at San Pablo, East Oakland, and Los Angeles were analyzed using Positive Matrix Factorization (PMF). Seven PM source-factors were identified at all locations: Factor1- Gasoline+Motor Oil+Meat Cooking+Natural Gas+SOA (31-53% PM mass), Factor 2- Diesel+Motor Oil (25-45% PM mass), Factor 3-Wood Burning (6-12% PM mass), Factor 4-Shipping and other heavy fuel oil combustion (2-3% PM mass), Factor 5-Sea Spray (4-8% PM mass), Factor 6-Sb Brake Wear (1-3% PM mass) and Factor 7-Sn - Unknown (1-7% PM mass). PM wood burning contributions were highest in the winter season when residential wood combustion was active. The monthly-averaged PM source apportionment results calculated by PMF are consistent with the PM source apportionment results calculated using Chemical Mass Balance (CMB) from the same sampling campaign. PMF distinguished Diesel+Motor Oil from Gasoline+Motor Oil+Meat Cooking+Natural Gas+SOA based on the species EC3 (a sub-fraction of elemental carbon that is volatilized and oxidized at temperatures between 700 and 775 °C), but PMF failed to further resolve the major sources of PM OC because unique tracers were not measured. PMF resolved "Shipping and other heavy fuel oil combustion" and Sea Spray sources based on inorganic tracers V and Br. The PMF factor rich in Sb very likely comes from brake wear associated with on-road vehicles and railway operations. The undefined Sn factor may be indicative of local industrial sources and traffic emission, but further research will be required to confirm this hypothesis. The PM source apportionment results contained in the current study further characterize the seasonal and spatial patterns of UFP concentrations in California.
超细颗粒（UFPs）是一种新兴的空气质量关注点，因为它们比空气中较大的颗粒具有更高的毒性。本研究旨在更好地了解加利福尼亚州多个地点 UFP 质量（PM）的来源贡献。在圣巴勃罗、东奥克兰和洛杉矶进行了为期一年的 PM 三小时平均样本收集，并使用正矩阵因子分析（PMF）进行了分析。在所有地点都确定了七个 PM 源因子：因子 1-汽油+发动机油+肉类烹饪+天然气+SOA（31-53%PM 质量），因子 2-柴油+发动机油（25-45%PM 质量），因子 3-木材燃烧（6-12%PM 质量），因子 4-航运和其他重油燃烧（2-3%PM 质量），因子 5-海水喷雾（4-8%PM 质量），因子 6-Sb 刹车片磨损（1-3%PM 质量）和因子 7-Sn-未知（1-7%PM 质量）。在冬季，当居民燃烧木材时，PM 木材燃烧的贡献最高。PMF 计算的每月平均 PM 源分配结果与同一采样活动中使用化学质量平衡（CMB）计算的 PM 源分配结果一致。PMF 根据 EC3 物种（元素碳的一个亚部分，在 700-775°C 之间挥发和氧化）区分柴油+发动机油和汽油+发动机油+肉类烹饪+天然气+SOA，但 PMF 未能进一步解析 PM OC 的主要来源，因为没有测量独特的示踪剂。PMF 根据无机示踪剂 V 和 Br 解析了“航运和其他重油燃烧”和海水喷雾源。富含 Sb 的 PMF 因子很可能来自与道路车辆和铁路运营相关的刹车片磨损。未定义的 Sn 因子可能表明当地工业源和交通排放，但需要进一步研究来证实这一假设。本研究中的 PM 源分配结果进一步描述了加利福尼亚州 UFP 浓度的季节性和空间模式。
