Abstract：Karl Fischer method can directly determine the water content of PM2.5 with good precision and accuracy. The method was applied to PM2.5 analysis of urban stations in Beijing in 2020, and the results showed that the annual average water concentration was (5.0±4.1) µg/m3, and the proportion of PM2.5was (12.5±4.8) %, which was significantly correlated with PM2.5 mass concentration. The monthly and seasonal variation trended of water concentration and PM2.5 mass concentration were basically consistent. The study found that with the increase of air pollution, the water concentration and its proportion in PM2.5 both showed an increasing trend, and the correlation between them was significantly enhanced. It can be seen that when pollution occurred, the increase of water concentration was conducive to the increase of moisture absorption of particles, thus pushing up the pollution level and enhancing the contribution to PM2.5 simultaneously. When dust pollution occurred, the humidity was at a low level in the same period, which was not conducive to the growth of moisture absorption of fine particles, the water concentration and its proportion were at a low level. There was a good correlation between water, secondary ions and organic matter, indicating that water provided heterogeneous transformation carrier for gaseous pollutants and promotes the further generation of fine particles such as nitrate, sulfate and organic matter. There was no correlation between water and crustal material, which proved that crustal elements were primary sources and were not affected by water.
陈圆圆, 李珺琪, 常淼, 沈秀娥, 刘保献. 北京市PM2.5水分含量及其变化特征[J]. 中国环境科学, 2023, 43(1): 70-76.
CHEN Yuan-yuan, LI Jun-qi, CHANG Miao, SHEN Xiu-e, LIU Bao-xian. Study on water content of PM2.5 and its variation in Beijing. CHINA ENVIRONMENTAL SCIENCECE, 2023, 43(1): 70-76.
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