南京冬季辐射雾和平流辐射雾的化学特征差异

Differences in Ion Compositions of Winter Fogwater between Radiation and Advection-Radiation Fog Episodes in Nanjing

利用2006和2007年冬季南京雾外场试验中取得的雾水离子成分资料,分析了雾水化学组分特征,探讨了雾水酸度来源及辐射雾和平流辐射雾的化学特征差异。结果表明,南京冬季雾水中总离子浓度偏高,浓度最高的3种离子成份是SO42-、NH4+和Ca2+,但雾水酸性不强,碱性离子成分的中和作用是pH值较高的原因。平流辐射雾中雾水离子总浓度约为辐射雾的2.2倍,平流辐射雾中浓度最高的阳离子为NH4+,辐射雾中为Ca2+。

Intensive field observations were conducted in the northern suburb of Nanjing during the win- ters of 2006 and 2007;and thirty-seven fogwater samples were collected in nine fog events. Based on the chemical analyses of the fogwater samples, the chemical characteristics and differences in the ion composition of fogwater between radiation and advection-radiation fog episodes are studied. The results show that the average TIC （Total Inorganic Ionic Concentration） value in fogwater was quite high, and the top three ion concentrations were those of SO^2-4, NH^＋4 and Ca^2＋;however,the average fogwater pH value was 5.85, which was attributable to the neutralization by basic ions. The average TIC value meas-ured in advection-radiation fogwater was around 2.2 times of that in radiation fogwater. The most abundant cation was NH^＋4 in the advection-radiation fog and Ca^2＋ in the radiation fog.