Polycyclic aromatic hydrocarbons (PAHs) associated with PM 2.5 within boundary layer: Cloud/fog and regional transport Minmin Yang a , Yan Wang a, ⁎, Hongli Li b, ⁎, Tao Li a , Xiaoling Nie a , Fangfang Cao b , Fengchun Yang a , Zhe Wang c , Tao Wang c , Guanghao Qie a , Tong Jin a , Lili Du a , Wenxing Wang d a School of Environment Science and Engineering, Shandong University, Jinan 250100, China b Environmental Monitoring Central Station of Shandong Province, Jinan 250101, China c Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China d Environment Research Institute, Shandong University, Jinan 250100, China HIGHLIGHTS • Cloud/fog effects on PAHs distribution within boundary layer. • Regional transport of PAHs in PM 2.5 and contributions of each direction. • Specific emission sources and quantita- tive analysis of their contribution. GRAPHICAL ABSTRACT abstract article info Article history: Received 21 August 2017 Received in revised form 2 January 2018 Accepted 3 January 2018 Available online Editor: Jianmin Chen A study of PM 2.5 -associated PAHs analysis at Mount Lushan (1165 m) was conducted to investigate the distribu- tions of PAHs in PM 2.5 and influences of cloud/fog. The main purpose was to quantify the main emission sources of PAHs and estimate regional transport effects within the boundary layer. Mount Lushan is located between the boundary layer and troposphere, which is an ideal site for atmosphere transport investigation. The concentra- tions of PAHs in PM 2.5 were analyzed with GC–MS. The results showed that the volume concentration was 6.98 ng/m 3 with a range from 1.47 to 25.17 ng/m 3 and PAHs mass were 160.24 μg/g (from 63.86 to 427.97 μg/ g) during the sampling time at Mount Lushan. The dominant compounds are BbF, Pyr and BP. In terms of aromatic-ring PAHs distributions, 4–6-ring PAHs are predominant, indicating that the high-ring PAHs tend to contribute more than low-ring PAHs in particulates. Due to frequent cloud/fog days at Mount Lushan, PAHs con- centrations in the PM 2.5 were determined before and after cloud/fog weather. The results demonstrated that the cloud/fog and rain conditions cause lower PAHs levels. Regression analysis was used for studying the relationship of PAHs distributions with meteorological conditions like temperature, humidity and wind. The results showed that the temperature and wind speed were inversely related with PAHs concentration but humidity had no sig- nificant relationship. Furthermore, backward trajectories and PCA combined with DR (diagnostic ratio analysis) were employed to identify the influences of regional transport and main emission sources. The results revealed that PAHs in PM 2.5 were mainly affected by regional transport with the main emissions by mobile vehicle and steel industry, which contributed about 56.0% to the total PAHs in the area of Mount Lushan. In addition, Keywords: PAHs PM 2.5 Cloud/fog Emissions Regional transport Mount Lushan Science of the Total Environment 627 (2018) 613–621 ⁎ Corresponding authors. E-mail addresses: wy@sdu.edu.cn (Y. Wang), lihongli1225@163.com (H. Li). https://doi.org/10.1016/j.scitotenv.2018.01.014 0048-9697/© 2018 Published by Elsevier B.V. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv February 2018 3