September: New paper from our group member

Congrats Dr. Lin Li for a new paper published on Frontiers of Environmental Science & Engineering.

恭喜李琳博士新文章发表！文章主要介绍了和2015年相比，2020年长江三角洲出现的高臭氧浓度值，来自于人为污染和气象变化的相对贡献。其中来自于人为排放源变化贡献了56%的臭氧浓度下降，气象变化贡献了44%。

Li, L., Li, J., Qin, M., Xie, X., Hu, J., and Zhang, Y.: Variations in summertime ozone in Nanjing between 2015 and 2020: roles of meteorology, radical chain length and ozone production efficiency, Front. Environ. Sci. Eng., 18, https://doi.org/10.1007/s11783-024-1897-z, 2024.

Abstract:

Changes in ozone (O₃) can be evaluated to inform policy effectiveness and develop reasonable emissions reduction measures. This study investigated the causes of summertime maximum daily 8-h average (MDA8) O₃ variation between 2015 and 2020 in Nanjing, China, a megacity in the Yangtze  River Delta (YRD) region, from the perspective of meteorological conditions and anthropogenic emissions of O₃ precursors (VOCs and NOx). Compared with 2015, the observed MDA8 O₃ decreased by 19.1 μg/m³ in August 2020. The indirect and indirect impacts of meteorological conditions contributed 44% of the decline, with temperature, relative humidity, and wind playing important roles in the O₃ variation. The O₃ drop by 10.7 μg/m³ (56% of the total decrease) may have been due to the decreases in anthropogenic emissions of VOCs and NOx by 7.8% and 11.7%, respectively. The longer hydroxyl (OH) radical chain length and higher ozone production efficiency (OPE) indicated that the reduction of anthropogenic emissions accelerated the ROx (ROx = OH + HO2 + RO2) and NOx cycles in O₃ production, making O₃ more sensitive to NOx. This corresponded to the O₃ formation shifting from a VOC-limited regime in 2015 to a transition regime in 2020 and O₃ decrease with anthropogenic emission reduction. Hence, the joint control of O₃ precursor emissions can effectively mitigate O3 pollution in Nanjing.