Center for Environmental Metrology, National Institute of Metrology China, Beijing 100029, China.
Center for Environmental Metrology, National Institute of Metrology China, Beijing 100029, China.
J Environ Sci (China). 2025 Mar;149:524-534. doi: 10.1016/j.jes.2023.10.031. Epub 2023 Oct 31.
Carbonaceous aerosol, including organic carbon (OC) and elemental carbon (EC), has significant influence on human health, air quality and climate change. Accurate measurement of carbonaceous aerosol is essential to reduce the uncertainty of radiative forcing estimation and source apportionment. The accurate separation of OC and EC is controversial due to the charring of OC. Therefore, the development of reference materials (RM) for the validation of OC/EC separation is an important basis for further study. Previous RMs were mainly based on ambient air sampling, which could not provide traceability of OC and EC concentration. To develop traceable RMs with known OC/EC contents, our study applied an improved aerosol generation and mixing technique, providing uniform deposition of particles on quartz filters. To generate OC aerosol with similar pyrolytic property of ambient aerosol, both water soluble organic carbon (WSOC) and water insoluble organic carbon (WIOC) were used, and amorphous carbon was selected for EC surrogate. The RMs were analyzed using different protocols. The homogeneity within the filter was validated, reaching below 2%. The long-term stability of RMs has been validated with RSD ranged from 1.7%-3.2%. Good correlation was observed between nominal concentration of RMs with measured concentration by two protocols, while the difference of EC concentration was within 20%. The results indicated that the newly developed RMs were acceptable for the calibration of OC and EC, which could improve the accuracy of carbonaceous aerosol measurement. Moreover, the laboratory-generated EC-RMs could be suitable for the calibration of equivalent BC concentration by Aethalometers.
含碳气溶胶，包括有机碳（OC）和元素碳（EC），对人类健康、空气质量和气候变化有重大影响。准确测量含碳气溶胶对于降低辐射强迫估算和源分配的不确定性至关重要。由于 OC 的碳化，准确分离 OC 和 EC 存在争议。因此，开发用于验证 OC/EC 分离的参考物质（RM）是进一步研究的重要基础。以前的 RM 主要基于环境空气采样，无法提供 OC 和 EC 浓度的可追溯性。为了开发具有已知 OC/EC 含量的可追溯 RM，我们的研究应用了改进的气溶胶生成和混合技术，提供了颗粒在石英滤纸上均匀沉积。为了生成具有类似环境气溶胶热解特性的 OC 气溶胶，同时使用了水溶性有机碳（WSOC）和水不溶性有机碳（WIOC），并选择无定形碳作为 EC 替代物。使用不同的方案对 RM 进行了分析。验证了滤膜内的均匀性，达到 2%以下。通过 RSD 为 1.7%-3.2%验证了 RM 的长期稳定性。两种方案测量的 RM 名义浓度与实测浓度之间存在良好的相关性，而 EC 浓度的差异在 20%以内。结果表明，新开发的 RM 可用于 OC 和 EC 的校准，可提高含碳气溶胶测量的准确性。此外，实验室生成的 EC-RM 可用于 Aethalometers 校准等效 BC 浓度。
