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Seasonal variations of transport pathways and potential sources of PM2.5 in Chengdu, China (2012–2013)
- Chen, Yuan, Xie, Shaodong, Luo, Bin
- Frontiers of environmental science & engineering 2018 v.12 no.1 pp. 12
- air, autumn, basins, cities, cluster analysis, dust, emissions, particulates, pollution, seasonal variation, spring, summer, winter, China
- Seasonal pattern of transport pathways and potential sources of PM₂.₅ in Chengdu during 2012–2013 were investigated based on hourly PM₂.₅ data, backward trajectories, clustering analysis, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) method. The annual hourly mean PM₂.₅ concentration in Chengdu was 97.4 mg·m–³. 5, 5, 5 and 3 mean clusters were generated in four seasons, respectively. Short-distance air masses, which travelled within the Sichuan Basin with no specific source direction and relatively high PM₂.₅ loadings (>80 mg·m–³) appeared as important pathways in all seasons. These short pathways indicated that emissions from both local and surrounding regions of Chengdu contributed significantly to PM₂.₅ pollution. The cities in southern Chengdu were major potential sources with PSCF>0.6 and CWT>90 mg·m–³. The northeastern pathway prevailed throughout the year with higher frequency in autumn and winter and lower frequency in spring and summer. In spring, long-range transport from southern Xinjiang was a representative dust invasion path to Chengdu, and the CWT values along the path were 30-60 mg·m–³. Long-range transport was also observed in autumn from southeastern Xinjiang along a northwesterly pathway, and in winter from the Tibetan Plateau along a westerly pathway. In summer, the potential source regions of Chengdu were smaller than those in other seasons, and no long-range transport pathway was observed. Results of PSCF and CWT indicated that regions in Qinghai and Tibet contributed to PM₂.₅ pollution in Chengdu as well, and their CWT values increased to above 30 mg·m–³ in winter.