The Potential source contribution function (PSCF) values were calculated to evaluate the potential source contribution to Black Carbon in the atmosphere of Tongyu (Figure 5), based on a total of 274 five‐day back trajectories arriving at the sampling site at 1200 (local time) of each day during the campaign. According to the results of the Potential source contribution function (PSCF) analysis, six potential source areas were identified as having important contributions to BC at the Tongyu. Source area I was the Yangtse River Delta (YRD) region and China Anhui Province, the North China Plain (NCP) region, and the Northeast China.