| The dissertation investigates the temporal and spatial distribution of air pollutants and the air quality and its changing trend of Liaocheng, an undeveloped city located in alluvial plain of the yellow river, by means of the investigating method, mathematical statistics method, Damel trending detecting method, single factor index method and the calculating formula of pollution index and pollution share rate. The research results are as following:（1） The characteristics of temporal and spatial distribution. The temporal distribution results are as follows. In diurnal variation aspect, the concentration of O3 increased significantly at 10:20 and reached the maximum level at about 14:20 to 15:20, and then decreased. The concentration of O3 keeps at analogous level at the other time of a day. The concentration of other air pollutants tended to rise at 7:20 and reached the maximum level at 11:20, followed by slight decline. At about 17:20, the concentration started to rise, however the value at night was usually less than the one at daytime. In seasonal variation aspect, the concentration of O3 was at the highest level in summer and at the lowest level in winter, while the other pollutants was in opposite. The inter-annual variation of NO2 in the same seasons was slight. The overproof times and rate of PM2.5 and PM10 were significantly higher than other pollutants. The sequence of various kinds of pollutants concentration during heating period and non-heating period are as follows: CO>PM10>PM2.5>SO2>NO2. The distinction of SO2 concentration between heating and non-heating period was the largest, as 53.5%. In inter annual variation aspect. The changing of PM10 was unstable, while the other pollutants are more stable. The concentrations of PM10 and PM2.5 in different yeas were all above the national secondary standard, while the CO and O3 never exceeded the standard.The spatial distribution results are as follows. The sequence of various pollutants concentration in Erqingji is as follows: CO>PM10>PM2.5>NO2>SO2>O3, while the sequences in district government and municipal party committee party school were both CO>PM10>PM2.5>SO2> NO2>O3. The distinction between concentration values of a same pollutant at different testing points was quite slight and the variation trend was similar. The concentration of CO was significant higher than other pollutants at different monitoring points. Besides, the concentrations of CO, PM10 and PM2.5 were obviously higher than NO2, SO2 and O3. Except for O3, the concentrations of other 5 pollutants decreased during January and February. Among them, CO, PM10 and PM2.5 decreased a lot, while NO2 and SO2 changed a little. At all monitoring points, the concentration of O3 keeps stable at maximum level from May to August, and the others keep at low level.The monthly averaged concentrations of CO and O3 at different monitoring points were all under standard and the situation optimistic. However, the concentration of PM10 and PM2.5 significantly exceeded the national standard every month and the situation was terrible. Besides, the overproof of NO2 and SO2 usually occurred during the periods from January to March and from September and December with small overproof times. The overproof of particulate matter in Erqingji was significant, compared with other two monitoring points. The overproof times of CO, SO2 and O3 in district government were higher than the other two monitoring points. And the overproof of NO2 in municipal party committee party school was more severe than the other two places.（2） Air quality condition and tendency. On the dynamic of air pollutants, PM10 in liaocheng city in the period of 2005-2014 was significantly on the rise, the NO2 increases significantly, while SO2 is on the decline, without significant change. Pollution of PM10 and automobile exhaust had a tendency to increase in the recent decade in Liaocheng city. From the condition of primary pollutant, we can see that PM2.5 and PM10 are respectively accounted for 63.4% and 23.3% of the total frequency, which indicates PM pollution holds the pivotal status in the air quality in Liaocheng city; Frequency of PM2.5 is much higher than other contaminants in each season including the heating duration and non-heating duration; 76.1 percent of 8hours of ozone occurrence frequency is concentrated in summer, which has a strong seasonality. While the occurrence frequency of NO2, SO2 and CO is quite low. The order of pollutant contribution is: PM2.5>PM10>NO2>SO2>CO. At each time level PM2.5 contribution rate is the highest, PM10 takes the second place, and both are much higher than other contaminants. It illustrates that Liaocheng city has a PM leading air pollution type. On the variation tendency of air quality, the days above Level 2 “good” accounts for 67.9 percent with a high rate, which is not optimistic. The quality grade in summer is the best while in winter the worst, and that in heating duration is good while in non-heating duration quite poor.（3） Air quality impact factor. Natural factors: Liaocheng city is located in the "bell" shape of the pollution belt, which is not conducive to the diffusion of pollutants. Rainfall is an important factor affecting the air pollution, the time of pollutants in low value stages matches to the period of precipitation concentration. Precipitation caused by the movement of air masses mainly concentrated in late spring and early autumn, and in summer the proportion is highest with the significantly impact to air quality. The dominant wind direction in Liaocheng is southerly, polluting enterprises mainly concentrated in the downwind area that is favorable for the prevention and control of pollution in urban areas. AQI is positively related with pressure, but negatively correlated with air temperature and wind speeds, both of them have reached a significant level（P < 0.05）, so these can explained that these three factors are the important factors affecting the air quality. Human impact factors: Heavy industry plays an important role in the industrial structures of Liaocheng, which determines the mean energy supply is coal, and as a result, coal demand is huge and it also resulte in coal-burning pollution. Catering and bath industry scattered small boilers heating and other domestic pollution sources, which are high energy consumption but low thermal efficiency, have an important influence on air quality. Large engineering constructions of the city will increase dust; raising green coverage rate plays an important role in the suppression of atmospheric particulates. The motor vehicle ownership in Liaocheng growths fast, emissions accounts for about 10% of the air pollutions, the main road with large traffic flow is an important source of pollutions. |
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