Pollution Status and Trend Analysis of Volatile Organic Compounds in the Ambient Air of Ningbo City

Based on the recent continuous monitoring data of 7 years,the pollution status and trend of volatile organic compounds(VOCs) in the ambient air of Ningbo city were analyzed.The results indicated that: a total of 94 species of VOCs were detected,and the major components were alkanes,aromatics,alkenes,halogen alkanes,halogen aromatics and oxygenated organic compounds,among which 37 species were toxic/hazardous with benzene,toluene,ethyl-benzene,and xylene(BTEX) exhibiting the highest concentration;the pollution status of BTEX in the ambient air of Ningbo City was at the same level with cities of domestic and abroad,and had not been deteriorated significantly in the recent years;distinct spatial patterns of VOC sources were identified,i.e.,natural source for functional zone I,combination of natural and anthropogenic source for functional zone II and industrial source for functional zone III;temporal trend of VOCs revealed that the average concentrations of VOCs in winter and spring were higher than other seasons and the diurnal variations of VOCs exhibited two peaks pattern,which correlated well with the variations of the traffic density.