Subjects: Geosciences >> Geography submitted time 2024-04-29 Cooperative journals: 《干旱区研究》
Abstract： Persistent cold air pools (PCAPs) in valley cities lead to the prolonged accumulation of air pollutants,thereby affecting the lives and health of residents. In this study, sounding data and daily air quality data from January 2013 to November 2023 were used to calculate and statistically analyze the characteristics of PCAPs occurrences in the Lanzhou Valley. In addition, the impact of PCAPs intensity on changes in pollutant concentrations was explored, and variations in pollutant concentrations during PCAPs were analyzed and compared with concurrent dust aerosol pollution. Results indicate that from 2013 to 2023, 59 PCAPs occurred, lasting cumulative 197days. During PCAPs, valley heat deficit and PM2.5 concentrations were 4.43 J·m−2 and 52.14 μg·m−3 higher, respectively, compared with non-PCAPs. The air quality index (AQI), SO2 concentration, NO2 concentration, CO concentration, and PM10 concentration increased by 70.37%, 144.3%, 84.3%, 156%, and 73.15%, respectively, whereas O3 concentration decreased by 60.89% during PCAPs. In PCAPs without dust aerosols, the average PM2.5:PM10 ratiowas 0.58, whereas in PCAPs with dust aerosols, the average ratio was 0.31. During PCAPs with concurrent dustaerosols, PM2.5 concentration, PM10 concentration, AQI, and O3 concentration increased by 18.33% , 133.03% ,84.44%, and 8.5%, respectively. However, SO2 and CO concentrations decreased by 17.54% and 17.88%, respectively. These findings can serve as a reference for atmospheric pollution prevention and management strategies in the Lanzhou region.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： This study was initiated to explore the pollution status of Lanzhou City in recent years and provide a reference for its prevention and management. The daily air quality index and mass concentrations of PM2.5, PM10, SO2, NO2, O3 (8 h, the 8 h moving average of ozone), and CO from 2014 to 2021 were used to analyze the monthly, seasonal, and interannual variation characteristics of air pollution in the valley city of Lanzhou. The changes in air pollutants and the continuous characteristics of air pollution in Lanzhou were also analyzed. The results show that the number of short- term mild continuous and long- term moderate and severe continuous pollution processes peaked in winter, the number of short- term moderate and severe continuous pollution processes peaked in spring, no moderate and severe continuous pollution processes occurred in summer, and longterm mild continuous pollution processes occurred more often in fall and winter. Pollutants that play a major role in the process of continuous pollution differ because of different seasons, durations, and grades of continuous pollution. The main pollutant in the mild, moderate, and short- term severe continuous pollution processes in winter is PM2.5, and the main pollutants in the long-term severe continuous pollution process are PM2.5 and PM10. The main pollutant in the continuous pollution process in spring is PM10, the main pollutant in the mild continuous pollution process in summer is O3 (8 h), the main pollutant in the short-term mild continuous pollution process in fall is PM10, whereas the main pollutants in the long-term mild continuous pollution process are PM10, PM2.5, and NO2.
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