The Source Apportionment of PM_2.5 Based on PCA-MLR Model in Lanzhou City

Objective To understand the pollution sources and source contribution rates of atmospheric PM_2.5 in different functional areas of Lanzhou City.

Methods Detecting the concentrations of metal elements, water-soluble ions and PAHs in PM_2.5 samples collected in Chengguan and Xigu district by inductively coupled plasma mass spectrometry, ion chromatography and high performance liquid chromatography respectively.The PCA-MLR model was used to investigate the pollution source and it's contribution.

Results The largest contribution to PM_2.5 was mixed pollution source of coal combustion and traffic emission in both districts.In Chengguan district, the major pollution sources were coal combustion and traffic emission, soil dusts, and biomass burning, with average contributions of 52%, 35% and 13% respectively.While in Xigu district, except the large parts of coal combustion/traffic emission (38%) and soil dusts (24%), the pollution from industrial production, coal combustion and secondary reaction also accounted for a certain proportion (38%) in total pollution sources.

Conclusion The largest contribution to PM_2.5 was mixed pollution source of coal combustion and traffic emission in Chengguan and Xigu districts of Lanzhou city.