Differences in aerosol hygroscopicity and influencing factors in various polluted environments in eastern China
Aerosol hygroscopicity is intricately linked to optical properties,activation potential,and lifespan.This study utilizes H-TDMA observational data from six sites across North China(Beijing,Xingtai,and Xinzhou)and the Yangtze River Delta(Baoshan,Dongtan in Shanghai,and Pukou in Nanjing)to investigate aerosol hygro-scopicity characteristics and influencing factors in diverse environments.Urban sites include Beijing and Baoshan(Shanghai),while Xingtai and Pukou(Nanjing)represent suburban areas heavily impacted by human pollution.In contrast,Xinzhou and Dongtan(Shanghai)are less-affected suburban locales.The findings reveal that particle hygroscopicity at North China sites generally exceeds that at Yangtze River Delta sites.Specifically,the average hygroscopicity parameter of 40 nm nucleation mode particles at North China sites is approxiamtely 0.1 higher,and 200 nm accumulation mode particles are about 0.06 higher,representing a 5.6％and 0.1％increase,repec-tively,compared to the same particle sizes at Yangtze River Delta sites.This disparity is attributed to the dense presence of heavy industries in North China,limited atmospheric dispersion,and significant emissions and accu-mulation of gaseous precursors,which foster the formation of highly hygroscopic secondary aerosols,such as sul-fates,under humid conditions.Overall,a significant divergence in aerosol hygroscopicity is observed across differ-ent emission backgrounds,with noticeable differences in hygroscopicity parameters between nucleation mode and accumulation mode particles across various North China sites.Urban site aerosols are heavily influenced by prima-ry emissions and predominantly comprise hydrophobic substances,resulting in weak hygroscopicity and pro-nounced external mixing characteristics.Suburban sites heavily impacted by human pollution exhibit stronger hy-groscopicity due to increased secondary aerosol formation.Conversely,less polluted suburban sites display inter-mediate hygroscopicity with a relatively higher internal mixing of particles.The marked variance in accumulation mode hygroscopicity at Yangtze River Delta sites is primarily attributed to the influence of marine aerosols,dis-tinct from those at North China sites.Excluding Xingtai,particle hygroscopicity generally increases with particle size across other sites,indicating that larger particles typically contain more hygroscopic substances.Frequent new particle formation events at the Xingtai site result in stronger hygroscopicity of nucleation mode particles,with 40 nm particle hygroscopicity values around 0.38,significantly higher than at the other two sites in the same region.Substantial emissions of primary aerosols during morning and evening peak hours generally diminish aerosol hy-groscopicity.Conversely,secondary aerosols generated by daytime photochemical reactions substantially enhance aerosol hygroscopicity,particularly evident at the three North China sites.These findings underscore the distinct differences in aerosol hygroscopicity across varying pollution environments,emphasizing the necessity for differ-entiation in simulations and studies addressing their impact on haze formation.The insights gleaned are of signifi-cant relevance for elucidating the mechanisms of air pollution formation and the radiative effects of aerosols.
aerosolhygroscopicityH-TDMAfield observationeastern China
国家科技期刊平台
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