Hong Xiuping, Yang Kang, Liang Handong, Shi Yunyun
Huaibei Normal University, Huaibei 235000, China.
School of Chemical & Environmental Engineering, CUMTB, Beijing 100083, China.
ACS Omega. 2022 Sep 26;7(40):35575-35585. doi: 10.1021/acsomega.2c02919. eCollection 2022 Oct 11.
Following the implementation of "coal-to-gas conversion" policy in the Haidian District of Beijing during summer, the present comparative study was performed employing 41 PM samples as precursors to analyze the characteristics of water-soluble inorganic ions. The concentrations of water-soluble inorganic ions in PM were analyzed by ion chromatography, and the occurrence form of ions was characterized via time-of-flight secondary ion mass spectrometry (TOF-SIMS). Results revealed that the daily average mass concentration of PM in Beijing during the sampling period was 94.28 ± 52.49 μg/m. As compared to the winter of 2016, the average daily PM concentration in Beijing decreased by 29 μg/m in 2017 (28.2% decrease), with a remarkable decline in the number of days with pollution. During the pollution period, the concentrations of NO , SO , and NH were significantly higher in PM as compared to the cleaning period. The ratio of the concentrations of [NO ]/[SO ] was greater than 1, and the contribution from mobile sources was relatively large, indicating that the implementation of the "coal-to-gas conversion" policy in Beijing has led to the reduction of SO emissions from fixed sources, such as coal. Furthermore, TOF-SIMS analysis results showed that NH tended to exist in the form of molecular ammonium sulfate or ammonium hydrogen sulfate during the period of pollution.
在北京海淀区夏季实施“煤改气”政策之后，本对比研究采用41个可吸入颗粒物（PM）样本作为前驱体来分析水溶性无机离子的特征。通过离子色谱法分析了可吸入颗粒物中水溶性无机离子的浓度，并通过飞行时间二次离子质谱（TOF-SIMS）对离子的存在形式进行了表征。结果显示，采样期间北京可吸入颗粒物的日均质量浓度为94.28±52.49μg/m³。与2016年冬季相比，2017年北京可吸入颗粒物日均浓度下降了29μg/m³（降幅为28.2%），污染天数显著减少。在污染期间，与清洁期间相比，可吸入颗粒物中NOₓ、SO₂和NH₃的浓度显著更高。[NOₓ]/[SO₂]的浓度比大于1，移动源的贡献相对较大，这表明北京实施的“煤改气”政策已使煤炭等固定源的SO₂排放量减少。此外，飞行时间二次离子质谱分析结果表明，在污染期间NH₃倾向于以硫酸氢铵或硫酸铵分子的形式存在。
