In situ chemical measurement of individual cloud residue particles at a mountain site, South China
Qinhao Lin1,2, Guohua Zhang1, Long Peng1,2, Xinhui Bi1, Xinming Wang1, Fred J. Brechtel3, Mei Li4, Duohong Chen5, Ping'an Peng1, Guoying Sheng1, and Zhen Zhou41State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China 2University of Chinese Academy of Sciences, Beijing, 100049, PR China 3Brechtel Manufacturing Inc., Hayward, 94544, California, USA 4Atmospheric Environment Institute of Safety and Pollution Control, Jinan University, Guangzhou 510632, PR China 5State Environmental Protection Key Laboratory of Regional Air Quality Monitoring, Guangdong Environmental Monitoring Center, Guangzhou 510308, PR China
Received: 10 Jan 2017 – Accepted for review: 06 Feb 2017 – Discussion started: 14 Feb 2017
Abstract. To estimate how atmospheric aerosol particles respond to chemical properties of cloud droplets, a ground-based counterflow virtual impactor (GCVI) coupled with a real-time single-particle aerosol mass spectrometer (SPAMS) was used to assess the chemical composition and mixing state of individual cloud residue particles in the Nanling Mountain Range (1,690 m a.s.l.), South China, in January 2016. The cloud residues were classified into nine particle types: Aged elemental carbon (EC), Potassium-rich (K-rich), Amine, Dust, Pb, Fe, Organic carbon (OC), Sodium-rich (Na-rich) and Other. The largest fraction of the cloud residues was the aged EC type (49.3 % by number), followed by the K-rich type (33.9 % by number). Abundant aged EC cloud residues that internally mixed with inorganic salts were found in air masses from northerly polluted areas. The number fraction (Nf) of the K-rich cloud residues significantly increased within southwesterly air masses from fire activities in Southeast Asia. In addition, the Amine particles represented 0.2 % to 15.1 % by number to the cloud residues when air masses changed from northerly to southwesterly sources. The Dust, Fe, Pb, Na-rich and OC particles had a low contribution (0.5–4.1 % by number) to the cloud residues. An analysis of the mixing state of cloud residues showed that the Dust and Na-rich cloud residues were highly associated with nitrate. Sulfate intensity increased in the aged EC and OC cloud residues and decreased in the Dust and Na-rich cloud residues relative to both ambient and interstitial particles. A comparison of cloud residues with interstitial particles indicated that a higher Nf for K-rich particles and a lower Nf for the aged EC particles were found in the cloud residues. Relative to the ambient and interstitial particles, the cloud residues exhibited larger size distributions. To our knowledge, this study is the first report on in situ observation of the chemical composition and mixing state of individual cloud residue particles in China. This study increases our understanding of the impacts of aerosols on cloud droplets in a remote area of China.
Lin, Q., Zhang, G., Peng, L., Bi, X., Wang, X., Brechtel, F. J., Li, M., Chen, D., Peng, P., Sheng, G., and Zhou, Z.: In situ chemical measurement of individual cloud residue particles at a mountain site, South China, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-23, in review, 2017.