雾环境汞在气溶胶内部化学转化动力学分析

Dynamics Analysis on Chemical Conversion of Mercury inside Aerosol in Fog

雾天气下气态总汞的浓度较高.基于大气汞的化学反应,建立汞的迁移转化动力学方程,采用吉尔方法开展雾环境气溶胶内部化学组分演化过程的研究,并定量分析气溶胶粒径、环境气态汞浓度对气溶胶化学组分浓度的影响.研究结果表明:在近一天的时间演化中,气态和液态臭氧浓度整体上呈现降低的趋势.对于粒径为1um、0.01um的气溶胶,演化初期气态臭氧的浓度分别降低0.703%和0.237%;而气溶胶内部二价汞的浓度相差不大;对于100um与1um的气溶胶,其粒径相差100倍,但气溶胶内部二价汞的浓度相差不足2倍,说明粒径小的气溶胶更容易富集汞.此外,环境气态汞Hg0的浓度较大时,气溶胶内部所吸收的液态Hg0浓度也随之增大;液态汞浓度达到最大值的时间约为演化12小时后,即一天中12点至16点期间气溶胶内部液态汞的浓度最高.

Concentration of total gaseous mercury in the fog is higher. Based on the chemical reactions of mercury, dynamical equations of mercury transformation were established, and the study of chemical composition evolution was carried out inside the aerosol by Gear method. Effects of aerosol size, initial concentration of gaseous mercury on aerosol chemical component concentration were analyzed qualitatively. The computed results show that gaseous and liquid ozone concentrations tend to be decreased during one day. For the aerosol sizes of lum and 0.01um, gaseous ozone concentrations were decreased by 0.703% and 0.237% during the initial stage of evolution process while there is little difference for two bivalent mercury concentrations inside the aerosols. For 100urn and lum of aerosol sizes, there is difference for I00 times between aerosol sizes, but there is approximately 2 times difference for the concentration of mercury inside aerosols, which suggests that it is easier to accumulate mercury inside fine aerosols. Moreover, when gaseous mercury Hg0 is at high concentration, the absorbed liquid concentration of Hg0 inside aerosols is increased. After 12 hours of evolution, liquid mercury concentration reaches its maximum. That is to say, high concentration is reached during a time period of 12 to 16 in one day.