Measurement And Study On BTEX In Atmospheric Environment In Nanjing

The thesis had described the research progress of volatile organic compounds (VOCs) in the air. The general situation of VOCs' survey in the ambient air and the origins of VOCs in the pollution of outdoor air were discussed emphatically. The sampling, clean-up and analytical methods of VOCs were described in brief. The indicators of personal exposures to VOCs and risk assessment of VOCs in the ambient air were particularly evaluated.In order to study the seasonal variation of BTEX in the urban air of Nanjing, the samples were collected in five sites from February 2005 to November 2005.The main results shows: the pollution of BTEX in the air of Nanjing is very serious and the total amount of BTEX, on the average, are 34.06 —92.49μg/m3.The discharge of tail gas vehicles is the main source of BTEX in the air of Nanjing.The diurnal variation of BTEX is: the concentrations of BTEX are highest at morning and lowest at noon, but upswing at evening. The lunar variation of BTEX is: autumn>summer>spring and winter. The concentrations of BTEX decrease with the descending of temperature. The horizontal distribution of the concentrations of BTEX is: traffic area>commercial and traveling area>living area> cultural and educational area>scenic spot.The concentrations of Toluene are higher than the concentrations of Benzen in all sampling sites and these are the highest of all BTEX. It demonstrates that the discharge of tail gas of vehicles is the main source of BTEX in the air of Nanjing. Benzene series are inspected in every sampling site and the inspection rates are very high. This indicates benzene series exist in outdoor air steadily and are able to reflect the pollution of VOCs. So we advise benzene series are inspected index in air quality.The result of concentrations of BTEX in atmosphere by the truck road is: the concentrations of BTEX at morning are highest because of the adverse temperature layer; the concentrations of BTEX at noon are lowest in atmosphere because that the adverse temperature layer is destroyed and it is better for diffusion; The concentrations of BTEX at afternoon upswing because of the quantity of cars are increasing.The precipitation can purge the atmosphere. It can be concluded that the pollution of BTEX in the atmosphere by truck road in Nanjing is very serious comparing with the cities around the world. It is required to fortify the regulation of vehicular tail gas and to exploit new gasoline.