Study On The Background Characteristics Of Three Gaseous Substances And Its Relationship With Weather Conditions In Summer And Winter At Linan

Yangtze River Delta is one of the most developed regions in China. The development of the industrialization and urbanization has impacted on the air quality seriously. Thus to analyze the changes of the surface pollutants of Yangtze River Delta has the most important signification. This paper based on the data of NO2, SO2and O3in Lin’an Atmospheric Background Monitoring Station in winter and summer from2003to2004, and analyzed the concentration of the three pollutants, the weekend effect, and the relation between them and meteorology conditions. The key findings in this study were summarized as follows:1. The day-to-day changes of NO2and SO2in winter had more fluctuations than them in summer; the interdiurnal variation of O3was contrary and the concentration of O3in winter was almost the same of in summer. The diurnal mean and hourly mean of NO2were hardly overstepped the air quality standard, but the rate of SO2to overstep the standard was very high,21.8%. It was high that the frequency of low NO2and SO2in summer, and low O3in winter. The diurnal variations of NO2showed a single valley and single peak distribution, the valley appeared during the day and the peak appeared during the night; the concentration of SO2was high during night and low during day without obvious peak and valley; diurnal variations of O3showed a single peak distribution and the peak appeared in the day.2. The concentrations of NO2and SO2in weekend were lower than weekday, and both of them were lower than Friday, and their lowest concentrations in winter were the days during the Spring Festival. O3did not have obvious "Weekend Effect". The highest concentration of NO2and SO2appeared in Friday, and the weekend always has the lowest appearance; the highest concentration of O3appeared in Wednesday. The concentrations of the pollutants began to reduce three days before the Spring Festival; and the concentration kept a low level during the Spring Festival Golden Week, but there was a peak appeared in the fifth day of Spring Festival holidays; after the Spring Festival, the concentration had increased rapidly.3. The diurnal variation of the concentration of O3is similar to that of temperature, the concentrations’diurnal variation of NO2and SO2are similar to that of RH. The concentration of NO2in rainy days is lower than the days without rains, the concentration is also higher in the noon; Precipitation clearance to SO2is high; the concentration of O3in rainy days is also much lower than the days without rains, this may be related to precipitation’s scavenging process to the Precursor things of O3. The high concentration of NO2in winter is relevant to the NE wind, while in the summer the direction of the wind is focus on NW and WNW; The relationship of SO2’s concentration and wind direction is similar to the relationship of NO2and wind direction, but the high concentration of SO2is relevant to SSW and WNW; The relationship of O3and wind direction is more complex, it is relevant to local O3. The concentrations of NO2and SO2in cloudy days are lower than in the sunny days, while03’s concentration only in the noon is slightly lower than in the sunny days.