Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science & Technology, Nanjing 210044, China.
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
Chemosphere. 2019 Apr;221:452-463. doi: 10.1016/j.chemosphere.2018.12.200. Epub 2019 Jan 4.
The North China Plain and the Yangtze River Delta are the two of the most heavily polluted regions in China. Observational studies revealed that 'explosive' PM mass concentration growths frequently occurred in the two regions. This study analyzed all the PM mass concentration growth processes from clean condition (i.e., <35 μg m) to heavy pollution condition (i.e., >150 μg m) in Beijing (BJ) and Shanghai (SH), two representative cities of the two regions, using hourly monitored PM concentrations during 2013-2016. 173 and 76 growth processes were identified in BJ and SH, respectively. PM rising rates (PMRR) and dynamic growth durations were calculated to illustrate the characteristics of the growth processes. Hourly particulate chemical composition data and meteorological data in BJ and SH were further analyzed. The 4-year averaged PMRR of PM total mass were similarly of 7.11 ± 9.82 μg m h in BJ and 6.71 ± 6.89 μg m h in SH. A decreasing trend was found for the PM growth processes in two cities from 2013 to 2016, reflecting the effectiveness of emission controls implemented in the past years. The contributions of particulate components to the PM total mass growth were different in BJ and SH. Average PMRR value of PM organic aerosols (OA), SO, NO, and NH in BJ was 1.90, 0.95, 0.82, and 0.53 μg m h, respectively. Average PMRR of PM OA, SO, NO, and NH in SH was 1.70, 1.18, 1.99 and 1.14 μg m h, respectively. Based on the contributions of different components, the PM mass concentration growth processes in BJ and SH were proposed to be classified into 'other components-dominant growth processes', 'all components-contributing growth processes', 'one or more explosive secondary components-dominant growth processes', and 'mixed-factor growth processes'. Potential source contribution function analysis and the meteorological condition analysis showed that source origins and prevailing wind for the two cities during different categories of growth processes had substantial difference. The important source areas included Hebei and Shandong for BJ, and Jiangsu and Anhui for SH. The dominant wind directions during growth processes were northeast, south and southwest in BJ, and were west to north in SH. The results suggested the contributing components, the prevailing wind conditions, and the formation processes were substantially different in the two cities, despite the similar PMRR of PM total mass during the growth processes between BJ and SH. Future research is needed to study the detailed formation mechanisms of the different PM mass concentration growth processes in the two cities.
华北平原和长江三角洲是中国污染最严重的两个地区。观测研究表明，这两个地区经常发生“爆炸式”PM 质量浓度增长。本研究利用 2013-2016 年期间在北京（BJ）和上海（SH）两个代表性城市每小时监测的 PM 浓度，分析了从清洁条件（即<35μg/m）到重度污染条件（即>150μg/m）的所有 PM 质量浓度增长过程。BJ 和 SH 分别识别出 173 和 76 个增长过程。计算 PM 上升率（PMRR）和动态增长持续时间以说明增长过程的特征。进一步分析了 BJ 和 SH 的逐时颗粒物化学成分数据和气象数据。BJ 和 SH 的 PM 总质量 4 年平均 PMRR 分别为 7.11±9.82μg/m h 和 6.71±6.89μg/m h。从 2013 年到 2016 年，两个城市的 PM 增长过程呈下降趋势，反映了过去几年实施的排放控制措施的有效性。BJ 和 SH 两个城市颗粒物成分对 PM 总质量增长的贡献不同。BJ 中 PM 有机气溶胶（OA）、SO、NO 和 NH 的平均 PMRR 值分别为 1.90、0.95、0.82 和 0.53μg/m h，SH 中 PM OA、SO、NO 和 NH 的平均 PMRR 值分别为 1.70、1.18、1.99 和 1.14μg/m h。基于不同成分的贡献，BJ 和 SH 的 PM 质量浓度增长过程被提议分为“其他成分主导增长过程”、“所有成分贡献增长过程”、“一个或多个爆炸式二次成分主导增长过程”和“混合因素增长过程”。潜在源贡献函数分析和气象条件分析表明，不同增长过程类别中，两个城市的源区和主导风向有很大差异。重要的源区包括河北和山东的 BJ，以及江苏和安徽的 SH。BJ 增长过程中主导风向为东北、南和西南，SH 为西至北。结果表明，尽管 BJ 和 SH 增长过程中 PM 总质量的 PMRR 相似，但两个城市的贡献成分、主导风向条件和形成过程存在很大差异。未来需要进一步研究两个城市不同 PM 质量浓度增长过程的详细形成机制。
