Characteristics Of VOCs And Their Photochemical Reactivity In Nanjing Northern Suburb

Currently, the pollution of urban photochemical has become the main atmospheric environmental problems which faced at home and abroad, this is not only harmful to people’s health, but also a threat to the natural environment for human survival. During March2011to February2012, a continuous observation campaign for one year period was carried out with the GC5000volatile organics online monitoring system and the EMS system in the northern suburb of Nanjing, and56VOC components and reactive gases (NOx, CO and O3) were measured. The results show that:The VOC hourly annual averaged volume concentration is about (43.52±22.38)×10-9, four seasons is not exactly the same as the composition ratio of VOCs and it has not obvious seasonal variation; the daily variation trend is consistent in four seasons, and the diurnal variation shows a bimodal characteristic, indicating the significant impact of motor vehicle emission, the minimum value of VOCs occurres at16:00.VOCs volume concentration of pollution Sources in the region is from the east. The speed of easterly and westerly wind on the transport and diffusion of VOCs are significantly different. UV radiation is an important influence factor of VOCs whose concentration changes during the day, and a correlation coefficient of0.91, and a negative correlation.Propylene-equivalent concentration method indicates that alkenes compound provides strong atmospheric chemical activity throughout the year; the next is aromatic; alkane is the most abundant substance of atmospheric VOCs in the Nanjing northern suburb, but do not contribute most to the production of O3.During the joint observation, the average OH consumption rate of VOCs in autumn in Nanjing northern suburb is approximately3.26×10-12cm3·molecule-1·s-1, and the largest incremental reactivity is about3.26mol·mol-1; Alkenes contribute the largest parts of OH consumption rate (LOH) and ozone formation potential (OFP), followed by aromatics. Although alkanes are the most abundant components of VOCs in the atmosphere, the key active components in VOCs are ethylene, propylene,1-butene, m,p-xylene, isoprene etc. The dominant factor of ozone formation is VOCs in this observation.