COVID-19管控期间苏州市PM2.5中金属元素浓度变化及来源解析

为了解COVID-19管控期间苏州市PM_2.5中金属元素浓度变化和来源，利用多金属在线监测仪于2019年12月1日～2020年3月31日测定了14种金属元素小时浓度，分析停产前、停产期和复工期金属元素浓度变化，并采用PMF模型分析其污染来源.结果表明，停产期Cr、 Mn、 Zn和Fe浓度降幅最大，较停产前分别降低了87.6%、 85.6%、 78.3%和72.2%;复工期Mn、 Cr、 Zn和Fe浓度升幅最大，较停产期分别增加了227.0%、 215.4%、 147.4%和113.4%.K在3个阶段日变化均不相同；Zn在3个阶段日变化均呈单峰形，但峰宽和峰值出现时间有所不同；Fe、 Mn、 Pb、 Se和Hg日变化无明显变化，仅仅是浓度发生了变化；Ca、 Ba、 Cu、 As、 Cr和Ni停产期和复工期日变化较停产前变化较大. PMF模型来源解析结果表明，金属元素主要来源于扬尘、机动车、燃煤、工业冶炼和混合燃烧源，其中工业冶炼源浓度变化最大，停产期浓度下降了89.0%,复工期浓度较停产期上升了358.0%.

Concentration Variation and Source Analysis of Metal Elements in PM2.5 During COVID-19 Control in Suzhou

To study the variation in concentration and source analysis of metal elements during COVID-19 control in Suzhou, a multi-metal online monitor was used to determine hourly online data of 14 metal elements from December 1, 2019 to March 31, 2020. This study analyzed variation in concentration and source analysis of metal elements using a PMF model before, during, and after shutdown during COVID-19 control. The results showed that the concentrations of Cr, Mn, Zn, and Fe during shutdown decreased the most, by 87.6%, 85.6%, 78.3%, and 72.2%, respectively, compared with those before shutdown. The concentrations of Mn, Cr, Zn, and Fe after shutdown increased the most, by 227.0%, 215.4%, 147.4%, and 113.4%, respectively, compared with those of the previous stage. The diurnal variation in K differed at three stages. Zn showed a single peak shape at three stages, but the peak width and peak time were different. Unlike the concentrations, the diurnal variations in Fe, Mn, Pb, Se, and Hg were not significantly changed. The daily variation characteristics of Ca, Ba, Cu, As, Cr, and Ni during and after shutdown were significantly different from those before shutdown. The results of source analysis by the PMF model showed that metal elements mainly came from dust, motor vehicle, coal burning, industrial smelting, and mixed-combustion sources. Among them, the concentration of industrial smelting sources changed greatly, with the concentration decreasing by 89.0% during shutdown and increasing by 358.0% after shutdown.