Study On Pollution Characteristics Of Water-soluble Ions In PM₁₀ And PM_2.5 In Lanzhou City

Air pollution, especially particulate pollution, has been a serious threat to human health for a long time. With the rapid urbanization and economic growth, air pollution is especially a serious problem in China. PM10 is the primary pollutant of atmospheric environment in our country now, and fine particle PM2.5 pollution is also growing in many cities. Analysis on water-soluble ions, which are the important composition of atmospheric particulates, can not only reflect the quality of the atmospheric environment to a certain extent and polluting characteristic of certain region, but also provide scientific basis to determine the sources and property of aerosol.This thesis is aim at the study on characteristic of water-soluble ions in PM10 and PM2.5 in Lanzhou city.The anions and cations of collected PM10 samples in Lanzhou was analyzed by the traditional filter method, in order to discuss the variation characteristics; Ambient Ion Monitor (URG-9000D) was used for the real-time monitoring of water-soluble ions in PM2.5, in order to probe the relationships between water-soluble ions and meteorological factors. The main conclusions are as follows:particulate pollution is serious during sampling period. PM10 mean mass concentration is the highest in March, and the lowest appears in May and June. Heating period activities and dust storm result in high concentration of PM10. NO3-, SO42-, NH4+ and Ca2+ are the major contributors to the PM10 water-soluble ions. The relationships between water-soluble ions and meteorological factors are as follows:during the dust storm, NO3- is positively correlated with temperature, but negatively correlated with relative humidity. SO42- is positively correlated with temperature, but negatively correlated with relative humidity. NH4+ is positively correlated with relative humidity, but negatively correlated with wind speed and temperature. During non-dust period, there is negative correlation between NO3-,SO42-, NH4+ and wind speed. The correlation between SO42-, NH4+ and relative humidity is positive during daytime, whereas NO3- is negatively correlated with relative humidity during nighttime.