临安秋季近地层臭氧的形成及其前体物特征

Photochemical Ozone and Characteristics of Its Precursors in the Boundary Layer of Lin′an,a Rural/Agricultural Site of Eastern China during 1999 Autumn

应用浙江临安1999年秋季观测数据,分析了臭氧及其前体物特征与气象条件的关系。结果表明,该地区臭氧前体物丰富,在合适的天气条件、充足的日照下可以生成高浓度的臭氧;CO、NOx*等一次污染物浓度与大尺度大气扩散稀释能力有关;观测期间临安CO浓度很高;NMHCs以芳香烃含量最高,烷烃、烯烃、炔烃次之,生物排放的烃最少。以观测为基础的光化学模式计算表明,临安光化学臭氧生成率比损失率大一个数量级,中午净臭氧生成率最大可达14.8×10-9h-1。

On the basis of data collected at Lin′an station during October/early November,we analyze the ozone and its precursor′s ((NOx)~*,CO,NMHC) characteristics and their relations to meteorological parameters.CO and (NOx)~* levels are related closely to macroscale synoptic system.On account of abundant ozone precursors at Lin′an station, the high O_3 will occur on a sunshine day.The aromatic is the largest part of NMHCs by carbon atom concentration,followed by alkane,alkene,alkyne and biogenic hydrocarbons.As a case study,we simulate photochemical ozone production rate P(O_3),depletion rate L(O_3) and the relative contributions of chemical reactions to ozone genesis/lysis by an observation-based photochemical box model.The results show that P(O_3) is one order of magnitude larger than L(O_3) in a clear autumn day of Lin′an.The net ozone production rate can reach up to 14.8×10^(-9)h^(-1) in the noontime.The sensitive experiments reveal that Lin′an net photochemical ozone production rate is highly sensitive to NMHCs.