Volume 16, No. 7, July 2016, Pages 1579-1590 PDF(3.01 MB)
Seasonal Variation, Sources and Transport of Aerosols at Lijiang, Southeast Tibetan Plateau
Ningning Zhang1,2, Junji Cao1,3, Rujin Huang1,4,5, Yuanqing He2, Qiyuan Wang1, Chongshu Zhu1
1 Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
2 State key Laboratory of Cryspheric science, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China
3 Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an, China
4 Laboratory of Atmospheric Chemistry, Paul Scherrer Institute (PSI), 5232 Villigen, Switzerland
5 Centre for Atmospheric and Environmental Studies, Xiamen Huaxia University, Xiamen 361024, China
- Crustal elements and anthropogenic source express difference seasonal variation.
- Sources of detected species were analyzed by PMF model, and 5 factor was found.
- Pre-monsoon is labeled by mixture pollutants transported from south Asia.
- Monsoon period is labeled by high loading of SO42– , NH4+ and heavy metal elements.
Aerosol samples were collected during pre-monsoon, monsoon and post-monsoon periods in 2009 in Lijiang, a tourism city located on the southeast Tibetan Plateau, southwest China. To determine the seasonal variation and sources of aerosol species, main elements and water soluble ions were analyzed. The results showed that crustal elements (Si, K, Ca, Ti and Fe) were the main elements with an enrichment whose enrichment factor (EF) value were lower than 10, with the large value (except Ca) occurring during the pre-monsoon period. The EF values of S, Cl, Zn, As, Br, Sb, Pb, and Cu were higher than those of the crustal elements and the large concentration appeared during the monsoon period. Ca2+ and SO42– were the dominant cation and anion, respectively. The greatest value of total ionic concentration was found during the monsoon period, mainly because of the high concentration of SO42– and NH4+. Using the positive matrix factorization model, it was found that the main sources of species were from crustal source, transport from south Asia and eastern China, local vehicle emissions and sea salt. Further results indicated that the pollutants mixed with dust, anthropogenic pollutants and biomass burning emissions can be transported to Lijiang from south Asia and Southeast Asia during the pre-monsoon period. In addition, pollutants rich in SO42– and heavy metal from the Sichuan Basin and eastern Yunnan Province can also be occasionally transported to Lijiang during the monsoon period. The seasonal differences in chemical composition and transportation pathway may have important implications for regional climate change.
Aerosol; Chemical composition; Sources identification; Transport pathway; Lijiang.