EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2026-6485 Chemical and dynamical controls on rapid secondary organic aerosol accumulation over a large lake in eastern China Tian Zeyuan 1 2 3 Wang Jiaping 1 2 3 Ding Dian 2 3 Ding Ke https://orcid.org/0000-0002-6436-6226 1 2 Wang Jiandong https://orcid.org/0000-0003-3000-622X 4 5 Yao Lei https://orcid.org/0000-0002-2680-1629 6 7 Li Chuang https://orcid.org/0000-0003-3448-9548 8 Yang Gan 8 Zhou Jiayi 8 Wang Ning 8 Liu Yuliang https://orcid.org/0000-0002-0028-9102 2 3 Liu Tengyu https://orcid.org/0000-0002-3137-5898 2 3 Nie Wei https://orcid.org/0000-0002-6048-0515 2 3 Yan Chao https://orcid.org/0000-0002-5735-9597 3 9 Wang Jinbo 2 3 12 Lin Qihao 1 2 Zhang Zhouyang 4 5 Wang Bin 4 5 Zhou Chang https://orcid.org/0009-0001-6930-2993 2 3 Zhu Caijun 2 3 Wang Zhenning 2 3 Wang Jianxun 3 9 Wang Lin https://orcid.org/0000-0002-4905-3432 7 8 10 11 Huang Xin https://orcid.org/0000-0003-0922-5014 1 2 State Key Laboratory of Severe Weather Meteorological Science and Technology, Nanjing University, Nanjing 210023, China Joint International Research Laboratory of Atmospheric and Earth System Sciences, School of Atmospheric Sciences, Nanjing University, Nanjing 210023, China National Observation and Research Station for Atmospheric Processes and Environmental Change in Yangtze River Delta, Nanjing 210023, China State Key Laboratory of Climate System Prediction and Risk Management, Nanjing University of Information Science and Technology, Nanjing 210044, China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China Shanghai Key Laboratory of Air Quality and Environmental Health, Department of Environmental Science and Engineering, Jiangwan Campus, Fudan University, Shanghai 200438, China Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China Nanjing-Helsinki Institute in Atmospheric and Earth System Sciences, Nanjing University, Nanjing 210023, China National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Shanghai 200438, China IRDR International Center of Excellence on Risk Interconnectivity and Governance on Weather/Climate Extremes Impact and Public Health, Fudan University, Shanghai 200438, China now at: National Satellite Meteorological Center (National Center for Space Weather), China Meteorological Administration, Beijing 100081, China 09 11 2026 2026 1 18 Copyright: © 2026 Zeyuan Tian et al. 2026 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6485/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-6485/egusphere-2026-6485.pdf

Lake-induced meteorological conditions can influence the formation and spatial distribution of secondary organic aerosol (SOA) by modulating precursor mixing, chemical processing, and aerosol transport. Yet how these processes act together to drive rapid SOA accumulation remains insufficiently understood. Here we conducted comprehensive measurements of aerosol composition at Taihu Lake in the Yangtze River Delta during the summer of 2023. Throughout the campaign, organic aerosol (OA) dominated submicron particulate matter (PM<sub>1</sub>) mass, accounting for 56 % of the total PM<sub>1</sub> (compared to 41 % at a nearby suburban station), with secondary components comprising 84 % of the total OA at Taihu Lake. During a prominent pollution episode (August 10&ndash;12), OA reached 73.7 &mu;g m<sup>-3</sup> (78 % of PM<sub>1</sub>), and the SOA fraction rose to 90 %. This rapid SOA accumulation was driven by a unique physicochemical synergy at the lake-land interface. The convergence of anthropogenic and biogenic emissions supplied a highly reactive precursor pool, while enhanced atmospheric oxidation capacity promoted rapid oxidation and aerosol aging, leading to efficient SOA formation. As revealed by modeling analyses, the lake&ndash;land thermal contrast further drove a pronounced lake&ndash;land breeze circulation, inducing localized subsidence over the lake that efficiently transported SOA formed aloft down to the surface, thereby favoring its rapid accumulation. These findings suggest that lake environments can provide favorable chemical and meteorological conditions for efficient SOA production, highlighting the need to consider large inland lakes in assessments of regional aerosol chemistry and air quality.

 National Natural Science Foundation of China 42475116 42422505