title: Chemical characteristics of PM1/PM2.5and influence on visual range at the summit of Mount Tai, North China.
abstract: Daytime and night-time PM1and PM2.5samples were simultaneously collected at the summit of Mount Tai during summer and autumn 2014. The mass concentrations and chemical compositions were analysed to determine the temporal variations of PM1and PM2.5and their contributions to visibility impairment. In summer, the average mass concentrations of PM1and PM2.5were 38.16μg/m3and 53.33μg/m3, respectively. In autumn, the values were 42.75μg/m3and 59.16μg/m3. Water-soluble inorganic ions were the most abundant species in both PM1and PM2.5, followed by organic mass (OM). Among the major water-soluble ions, SO42-and NH4+had higher concentrations in summer than in autumn, whereas the concentration of NO3-showed the opposite seasonal trend. Lower concentrations of organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) were obtained in summer than in autumn. The water-soluble components (SO42-, NO3-, NH4+and WSOC) showed a clear diurnal variation due to the specific meteorological conditions of Mount Tai. The water content in PM1and PM2.5was enhanced by the water-soluble components, especially NH4NO3. The decreased visibility resulted from the combined influence of particulate matter and relative humidity (RH). The threshold PM2.5concentration corresponding to a visibility of <10km was 56.60μg/m3, which decreased with an increase in RH. A revised IMPROVE equation was applied to estimate the light-extinction coefficient bext, which was found to be lower for these chemicals in autumn (364Mm-1) than in summer (482Mm-1). (NH4)2SO4made the largest contribution to bextin both summer and autumn, with an average rate of 56.97%. OM (17.32%) and NH4NO3(15.13%) were also important contributors, with similar contribution rates. The contribution of NH4NO3to bextwas higher during summer, and OM contributions were higher during autumn.
authors: Environment Research Institute, Shandong University, Jinan 250100, China.
authors: Tong
authors: T
authors: Zhao
authors: Environment Research Institute, Shandong University, Jinan 250100, China; School of Environmental Science and Engineering, Shandong University, Jinan 250100, China; Jiangsu Collaborative Innovation Center for Climate Change, China. Electronic address: yanglingxiao@sdu.edu.cn.
authors: Lingxiao
authors: L
authors: Yang
authors: School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
authors: Weida
authors: W
authors: Yan
authors: Environment Research Institute, Shandong University, Jinan 250100, China.
authors: Junmei
authors: J
authors: Zhang
authors: School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
authors: Wei
authors: W
authors: Lu
authors: School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
authors: Yumeng
authors: Y
authors: Yang
authors: Environment Research Institute, Shandong University, Jinan 250100, China; School of Environmental Science and Engineering, Shandong University, Jinan 250100, China; Jiangsu Collaborative Innovation Center for Climate Change, China; Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Fudan Tyndall Centre, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
authors: Jianmin
authors: J
authors: Chen
authors: Environment Research Institute, Shandong University, Jinan 250100, China.
authors: Wenxing
authors: W
authors: Wang
keywords: Chemical characteristics; PM(1)/PM(2.5); Relative humidity; Visibility