[Concentration Characteristics and Source Analysis of PM_2.5 During Wintertime in Zhengzhou-Xinxiang]

To study the pollution characteristics, sources, and transportation process of PM_2.5 and its chemical compositions in the Zhengzhou-Xinxiang region, PM_2.5 samples were collected using a middle volume sampler, in Zhengzhou and Xinxiang urban areas for 30 consecutive days during the winter of 2016. The mass concentration of PM_2.5 was measured gravimetrically. 17 trace metals were determined by inductively coupled plasma-mass spectrometry (ICP-MS), and 7 water-soluble ions were determined by ion chromatography. The enrichment factor (EF) method and principal component analysis were employed to determine the source apportionment. The results showed that the daily mean PM_2.5 mass concentration during the winter sampling period of 2016 in Xinxiang and Zhengzhou was 223.87 μg·m^-3 and 226.67 μg·m^-3, respectively, which indicated that pollution levels were relatively high in both cities. The concentration of three macro elements (Al, Ca, and Fe) accounted for 50% of the total metal elements in both cities, while the heavy metals concentration was higher in Xinxiang than in Zhengzhou. The EFs of Cd, Ag, and Pb in Xinxiang were far higher than 1000, while only Cd was higher than 1000 in Zhengzhou. NO₃^-, SO₄^2-, and NH₄⁺ were the main ions in the two cities. They exceeded 94% of total water-soluble ions and existed in the forms of (NH₄)₂SO₄ and NH₄NO₃. The principle component analysis showed that the main contributors to PM_2.5 were a mixture of biomass combustion and secondary aerosol in Xinxiang, and a mixture of coal combustion and traffic emissions in Zhengzhou, accounting for 34.94% and 33.99% of total PM_2.5 emissions, respectively.