| Our society has developed rapidly and has made great achievements especially in economic development since the industrial revolution.However, while we were creating the glorious material wealth, we consumed a lot of energy, produced a large number of air pollutants which are affecting the earth’s ecological balance and the climate change. It is a great threat to the survival and development for human society. Such issues as photochemical smog and acid rain have become frontier problems in global atmospheric science research. Among which the surface layer of ozone, nitric oxides, sulfur dioxide, inhalable particle, carbon monoxide and lead are called the six main atmospheric pollutants by the US EPA. Therefore, long-term effective observation to the regional atmospheric pollutions such as SO2, NOx, O3, PM2.5 and VOCs will help us a lot to understand the causes of regional compound pollution. It provided scientific guarantee and made effective policies for the sustainable development of human. As one of the China’s four municipalities directly under the central government, Chongqing is the largest city and also one of the most important old industrial bases in Southwest China. So the air pollution is very serious and Chongqing is known as "foggy city". However, the observation and research in atmospheric pollutions of Chongqing is relatively weak. The observation time was from March 2012 to February 2014 in this study. The author collected atmospheric samples regularly in Beibei urban area in Chongqing with special sampling steel cylinders, analyzed the composition of VOCs. At the same time, the author obtain high quality data of SO2, NOX, O3, PM2.5 using the on-line continuous monitoring equipment to research the features of atmospheric pollution from Beibei of Chongqing and revealed the composition features and its origin, seasonal variation and photochemical characteristics. It will provide scientific basis and data support for Beibei district of Chongqing’s air quality control and management. This study obtained the conclusions as follows:(1) The annual volume fraction of TVOCs between 2013-2014 in Beibei urban area of Chongqing is 41.73×10-9.It appears no clearly different from 2012-2013 (33.89×10-9). Among which the alkanes accounted for the highest proportion with 41.36%, hydrocarbon accounted for the lowest proportion with 14.35%; the annual variation rule is in order of spring (43.25×10-9)> summer (43.08×10-9)> autumn (41.18×10-9)> winter (37.41×10-9).Olefin contributed the most proportion to ozone generation in Beibei area’s atmosphere VOCs.Its volume fraction was only 14.35%, but the contribution rate reached up to 48.19%. The VOCs components which have higher contribution to ozone generation are isoprene (11.15%), propylene (10.39%), 1,3-butadiene (7.08%), so controling the olefin in atmosphere is of great significance to reduce the concentration of O3. Motor vehicle exhaust emission, chemical source and leakage of oil and gas are the primary pollution sources of Beibei atmosphere VOCs. Among which the motor vehicle exhaust emission is the biggest pollution source, contributed 50.56%.(2) During 2012 and 2013, PM2.5 is the most serious pollutant in Chongqing Beibei’s atmosphere, hazy weather emerged frequently in winter and the days exceed standard are in majority, it is influenced by the local emission source and the regional air transportation;O3 is generated by the photochemical process of accumulation and pneumatic conveyor, compared with 2012, O3 pollution in 2013 is aggravating, annual average concentration increased 17.4 μg·m-3. NOx exceeding days are doubling, annual average concentration has no apparent change; SO2 pollution is the lightest, in addition to once beyond index in hourly average in 2013, all the rest are below the national secondary standard; the daily change rules of atmospheric pollutants changed various, but the daily change rules were almost the same in spring, summer, autumn and winter, O3 and Ox showed evident unimodal type change, the peak appeared in 4:00 PM; NO and NOx’s changing had the feature of "peak in the morning and valley in the noon", and the NO2 and PM2.s’s changing had a trend of bimodal type, the peak appeared in the morning and evening; the distribution of SO2 changed unimodally, the peak appeared in the morning, and in the evening it reached the minimum.(3)The distribution characteristics of each pollutants concentration were different under different weather condition, the overall characterics was that the concentration was low on rainy days, and high on cloudy days and sunny day. Rainfall had obvious influence on the pollution concentrations, but temperature, relative humidity and wind speed had different degrees of influence on pollutant. It had significant change to O3 and NOx concentration, the O3 would be high with the high temperature, small wind and low humidity, and it was opposite to the NOx. PM2.5 performed differently under different weather conditions, but its correlations with meteorological factors overall performed are as sunny> cloudy> overcast. SO2 and meteorological elements are negatively correlated, mainly affected by temperature. |
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