Department of Civil and Environmental Engineering, University of California-Davis, Davis, CA, USA.
Department of Civil and Environmental Engineering, University of California-Davis, Davis, CA, USA.
Sci Total Environ. 2022 Sep 10;838(Pt 4):156523. doi: 10.1016/j.scitotenv.2022.156523. Epub 2022 Jun 6.
Measurement networks for ultrafine particulate matter (PM) have been limited by the high costs for equipment, supplies, and labor associated with the need to collect PM samples on multiple substrates for full chemical analysis. Here we explore whether a single cascade impactor loaded with aluminum foil substrates is sufficient for PM source apportionment calculations in order to reduce those costs. An extraction method previously designed to measure elements on Teflon substrates was modified to accommodate features of aluminum foil substrates. Regression analysis between co-located aluminum foil and Teflon substrates in the particle diameter range 0.1-1.8 μm showed good agreement (R > 0.7) for 18 elements. Regression in the diameter range 0.1-0.18 μm (quasi-ultrafine particulate matter) was used to characterize the uncertainty introduced by the aluminum foil extraction method for the elements Li, K, V, Br, Rb, Mo, Cd, Sn, Sb, and Ba. This uncertainty was used to generate 30 simulated aluminum foil PM datasets at each of three sites, followed by source apportionment analysis using Positive Matrix Factorization (PMF). At two of the three sites, the PM source contributions calculated using aluminum foil substrates alone were almost identical to the PMF results from combined aluminum foil and Teflon substrates. The PM source contributions calculated using aluminum foil substrates at the third site were closer to the results from a previous Chemical Mass Balance (CMB) study than to the PMF results from the combined aluminum foil and Teflon substrates, possibly because the CMB study also relied exclusively on samples collected using aluminum foil substrates. The success of the PM source apportionment approach using aluminum foil substrates in a single cascade impactor provides a viable method for reducing costs in PM sampling networks by 40-47%. Similar results may be achievable at locations outside of California.
用于超细颗粒物 (PM) 的测量网络受到限制，原因是设备、耗材和劳动力成本很高，需要在多个基底上收集 PM 样本以进行全面的化学分析。在这里，我们探讨了在单个级联冲击器上加载铝箔基底是否足以进行 PM 源分配计算，以降低这些成本。先前设计用于测量特氟隆基底上元素的提取方法进行了修改，以适应铝箔基底的特点。在 0.1-1.8μm 的粒径范围内，对共定位的铝箔和特氟隆基底进行回归分析，结果表明 18 种元素的相关性很好（R>0.7）。在 0.1-0.18μm 的直径范围内（准超细颗粒物）的回归用于表征铝箔提取方法对 Li、K、V、Br、Rb、Mo、Cd、Sn、Sb 和 Ba 等元素的不确定性。在每个地点进行了 30 次模拟的铝箔 PM 数据集的生成，然后使用正矩阵因子化 (PMF) 进行源分配分析。在三个地点中的两个地点，使用铝箔基底单独计算的 PM 源贡献与使用铝箔和特氟隆基底组合计算的 PMF 结果几乎相同。在第三个地点使用铝箔基底计算的 PM 源贡献更接近之前的化学质量平衡 (CMB) 研究结果，而不是使用铝箔和特氟隆基底组合的 PMF 结果，这可能是因为 CMB 研究也仅依赖于使用铝箔基底收集的样本。在单个级联冲击器中使用铝箔基底进行 PM 源分配的方法的成功提供了一种可行的方法，可以将 PM 采样网络的成本降低 40-47%。在加利福尼亚州以外的地点，可能会取得类似的结果。
