State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
Sci Total Environ. 2022 Feb 1;806(Pt 4):150950. doi: 10.1016/j.scitotenv.2021.150950. Epub 2021 Oct 14.
The vertical distribution of carbonaceous aerosol impacts climate change, air quality and human health, but there is a lack of in-situ vertical observations of black (BC) and brown carbon (BrC). Thus, the characteristic of vertical profiles of BC concentration, particle number concentration (PNC), O concentration and optical absorption of BC and BrC were observed in a suburban site over North China Plain, where heavy pollution of PM and O always occurred in winter and summer, respectively. In winter, during a heavy pollution episode, the BC and PNC was near uniformly distributed within mixing layer (ML) (15.2 ± 6.7 μg m and 678 ± 227 p cm, respectively) and decreased with altitude above the ML. The BC heating rate reached about 0.13 K h during the heaviest pollution day. In summer, the BC concentration (2.9 ± 1.3 μg m) in ML during the middle O pollution events was higher than that (1.7 ± 0.6 μg m) during the light O pollution. The light absorption coefficients of BC at 880 nm and BrC at 375 nm measured in the early morning were lower than that in the daytime, and the contribution of BrC to total light absorption of carbonaceous aerosols was in the range of 27-47%. In addition, BC was effectively transported to high altitude than BrC in the daytime. The light absorption of secondary BrC in the daytime was higher 10-20% than that in the early morning. Simultaneously, the contribution of secondary BrC to the total BrC light absorption at 375 nm was range from 32% to 68% within 1000 m.
黑碳（BC）和棕色碳（BrC）的原位垂直观测较为缺乏，而其垂直分布会影响气候变化、空气质量和人类健康。因此，本研究在中国华北平原的一个郊区站点观测了冬季（PM 和 O 污染严重）和夏季（PM 和 O 污染较轻）BC 浓度、粒子数浓度（PNC）、O 浓度和 BC 及 BrC 的光吸收垂直廓线特征。在冬季重度污染期间，BC 和 PNC 在混合层（ML）内近均匀分布（分别为 15.2±6.7μg/m 和 678±227 p cm），并随 ML 以上高度的增加而降低。重度污染日，BC 的加热率约为 0.13 K/h。在夏季，中度 O 污染期间 ML 中的 BC 浓度（2.9±1.3μg/m）高于轻度 O 污染期间（1.7±0.6μg/m）。在清晨测量的 880nm 处 BC 和 375nm 处 BrC 的光吸收系数低于白天的值，BrC 对碳质气溶胶总光吸收的贡献在 27%-47%之间。此外，在白天，BC 比 BrC更有效地被输送到高空。白天生成的 BrC 的光吸收比清晨高 10%-20%。同时，在 1000m 范围内，二次 BrC 对 375nm 处总 BrC 光吸收的贡献在 32%-68%之间。
