10th International Aerosol Conference
September 2 - September 7, 2018
America's Center Convention Complex
St. Louis, Missouri, USA

Abstract View


Atmospheric New Particle Formation from Sulfuric Acid and Amines in a Chinese Megacity

Lei Yao, Olga Garmash, Federico Bianchi, Jun Zheng, Chao Yan, Jenni Kontkanen, Heikki Junninen, Stephany Mazon, Mikael Ehn, Pauli Paasonen, Mikko Sipilä, Mingyi Wang, Xinke Wang, Shan Xiao, Hangfei Chen, Yiqun Lu, Bowen Zhang, Dongfang Wang, QingYan Fu, Fuhai Geng, Li Li, Hongli Wang, Liping Qiao, LIN WANG, et al., Fudan University

     Abstract Number: 318
     Working Group: Air Quality in Megacities: from Sources to Control

Abstract
Atmospheric new particle formation (NPF) is a global and important phenomenon that is yet extremely sensitive to ambient conditions. According to both observation and theoretical arguments, NPF usually requires a relatively high H2SO4 concentration to promote the formation of new particles and a low pre-existing aerosol loading to minimize the sink of new particles. However, recent observations of NPF in heavily-polluted megacities, despite enormous aerosol loadings that correspond to a large condensation sink, contradict previous knowledge that newly-formed molecular clusters should be efficiently scavenged before they reach sizes of a few nanometers, making it one of the least understood topics in atmospheric chemistry. Here, we investigated NPF in Shanghai and were able to observe both precursor vapors (H2SO4) and initial clusters at a molecular level in a megacity. High new particle formation rates were observed to coincide with several familiar markers suggestive of H2SO4-dimethylamine (DMA)-H2O nucleation, including sulfuric acid dimers and H2SO4-DMA clusters. The initial growth up to around 3 nm could be explained qualitatively by H2SO4 and neutralizing bases under the very high urban condensation sink, whereas the subsequent faster growth rate above this size is believed to result from the added contribution of condensing organic species. These findings will help to understand urban NPF and its air quality and climate impact as well as to formulate policies to mitigate secondary particle formation in China.