Hourly BC concentrations ranged from 77.61 ng m−3 to
59.55 mg m−3 with an average of 2.52 mg m−3
, showing a clear seasonal pattern with high
values in spring, fall, and winter and low values in summer. Events of high BC
concentrations occurred frequently in spring as a result of long‐range transport of polluted
air masses from the north, northwest, and south in the atmosphere over the Asian
continent. The Yangtse River Delta (YRD) and China Anhui Province, the North China
Plain (NCP), Northeast China, the Mongolian boundary near China and Russia, Middle
Asia, and some areas of Russian Far East were major potential contribution sources for the
observed pollutants.