Abstract:Using the monitoring data of atmospheric pollution (PM2.5, SO2, NO2, CO, O3 and PM10) and meteorological data from 2015-2017 in Hefei, the characteristics of concentration changes of atmospheric pollutants in Hefei in summer and the influence of precipitation on atmospheric pollutants were analyzed. The results showed that: (1) The concentration of PM2.5 and PM10 declined from 2015 to 2017, and only NO2 in the gaseous pollutants showed an upward trend. (2) Diurnal variations of PM2.5 and PM10 displayed a bimodal pattern the peak values were (51.01±2.72) μg·m-3 at 8:00-9:00 and 21:00-22:00, and the lowest values were (30.64±1.86) μg·m-3 at 15:00-16:00. (3) Diurnal variation of O3 and SO2 displayed unimodal, the peak values were (129.35±12.52) μg·m-3 and (11.80±0.77) μg·m-3, respectively. (4) Summer precipitation can obviously affect air pollutants: O3 concentration fluctuation range reduced and the period of peak value shortened significantly; the concentrations of NO2 and CO declined obviously, NO2 night-value was about 55%-60% of non-precipitation conditions, and CO declined by 20%; the unimodal variation of SO2 disappeared, and hourly concentration maintained at 9.66 μg·m-3; both PM2.5 and PM10 concentration reduced, and the mass percentage of different size particles changed in precipitation, the radio of PM2.5/PM10 increased obviously during precipitation, and declined rapidly after precipitation.
