Exceedingly high levels of PM2.5 with complex chemical composition occur frequently in China. It has been speculated whether anthropogenic PM2.5 may significantly contribute to ice-nucleating particles (INP). However, few studies have focused on the ice-nucleating properties of urban particles. In this work, two ice-nucleating droplet arrays have been used to determine the atmospheric number concentration of INP (N-INP) in the range from 6 to 25 degrees C in Beijing. No correlations between N-INP and either PM2.5 or black carbon mass concentrations were found, although both varied by more than a factor of 30 during the sampling period. Similarly, there were no correlations between N-INP and either total particle number concentration or number concentrations for particles with diameters > 500 nm. Furthermore, there was no clear difference between day and night samples. All these results indicate that Beijing air pollution did not increase or decrease INP concentrations in the examined temperature range above values observed in nonurban areas; hence, the background INP concentrations might not be anthropogenically influenced as far as urban air pollution is concerned, at least in the examined temperature range.
ISI Document Delivery No.: FZ0MRTimes Cited: 6Cited Reference Count: 73Chen, Jie Wu, Zhijun Augustin-Bauditz, Stefanie Grawe, Sarah Hartmann, Markus Pei, Xiangyu Liu, Zirui Ji, Dongsheng Wex, HeikeWex, Heike/X-5882-2018Wex, Heike/0000-0003-2129-9323; Pei, Xiangyu/0000-0003-1150-3001National Natural Science Foundation of China [41475127, 41571130021]; Ministry of Science and Technology of the People's Republic of China [2016YFC0202801]; DFG [FOR 1525, WE 4722/1-2]; Swedish Research Council [639-2013-6917]This work is supported by the following projects: the National Natural Science Foundation of China (41475127, 41571130021) and the Ministry of Science and Technology of the People's Republic of China (2016YFC0202801) and by the DFG-funded Ice Nuclei Research Unit (INUIT, FOR 1525) (WE 4722/1-2) and the Swedish Research Council (639-2013-6917).610Copernicus gesellschaft mbhGottingen1680-7324