RESUMO
In order to explore the characteristics of PM2.5 concentration and water-soluble inorganic ions in Zhengzhou City, a total of 170 PM2.5 samples were collected in the spring, summer, autumn, and winter seasons of 2016, with 30 days continuous sampling during each season. The mass concentration of PM2.5 was analyzed gravimetrically, water-soluble inorganic ions were determined by ion chromatography, and principle component analysis was employed for source apportionment. The results showed that the mass concentration of PM2.5 was 150.72µg·m-3 during the sampling period. The mass concentration was highest in winter and lowest in summer, and that of autumn is higher was higher than that of spring. The ions SO42-, NO3-, and NH4+ were the major WSIs found in PM2.5, accounting for 92.55%, 92.94%, 93.06%, and 93.15% of the total amount of the seven ions found in spring, summer, autumn, and winter, respectively. The anion-to-cation ratio was 0.886, which indicated that PM2.5 was slightly alkaline in Zhengzhou. Secondary inorganic species, including NH4+, NO3-, and SO42- were the major components of the water-soluble ions. These ions most likely existed in the form of NH4NO3 and (NH4)2SO4 during spring and summer, while they were present as NH4NO3, (NH4)2SO4 and NH4HSO4 in autumn. In addition to these three forms, NH4Cl or other forms may exist in winter. Industrial emissions, combustion, secondary transformation, soil, and construction dust were the major sources of the water-soluble ions in PM2.5.
RESUMO
To study the pollution characteristics, sources, and transportation process of PM2.5 and its chemical compositions in the Zhengzhou-Xinxiang region, PM2.5 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 PM2.5 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 PM2.5 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-, SO42-, 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 PM2.5 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 PM2.5 emissions, respectively.