降水中汞的赋存形态

在北京市不同地点和不同时期采集降水样品 36个 .分析结果表明 ,汞易形成相对稳定的络合态汞 ,除 Hg⁰_(w) 外各形态汞含量均表现为采暖期大于非采暖期 .降水中各形态汞的含量和百分比按大小排序 ,经统计检验 ,在非采暖期水相中为 Hg^re_(w)>Hg⁰_(w),Hg²⁺_(w)],颗粒态汞为 Hg^re_(p)>Hg²⁺_(p)>Hg⁰_(p);在采暖期水相中均为 Hg^re_(w)>Hg²⁺_(w)>Hg⁰_(w),颗粒态汞为 Hg^re_(p)>Hg²⁺_(p),Hg⁰_(p)].在非采暖期颗粒态汞含量及百分比 Hg^T_(p)>溶解态汞 Hg^T_(w),在采暖期颗粒态汞和溶解态汞没有明显差异 .小于 0.45μm颗粒吸附的汞 Hg⁰相对较多 ,Hg²⁺形态汞较少 ,水溶液中 Hg⁰ 形态汞少 ,Hg²⁺形态汞多 ,表明 Hg⁰ 形态汞更易在微小颗粒物上吸附 ,而 Hg²⁺形态汞相当部分可以保留在水溶液中 .

Mercury Species in Precipitation

rainfall samples were collected in Beijing.Determination of volatile(Hg⁰),active(Hg²⁺)and inactive mercury(Hg^re)in water phase and particle of rainfall shown that except for Hg⁰_(w),the amount of rest mercury species during heating periods are higher than that during non heating periods.According to the contents and percentage of all mercury species in rainfall,which were checked by statistical test,the order was Hg^re_(w)>Hg⁰_(w),Hg²⁺_(w)] in water phase and Hg^re_(p)>Hg²⁺_(p)>Hg⁰_(p) in particle during non heating period;Hg^re_(w)>Hg²⁺_(w)>Hg⁰_(w) in water phase and Hg^re_(p)>Hg²⁺_(p),Hg⁰_(p)] in particle during heating period.In precipitation water,inactive mercury content is highest in both of water phase and particle.During non heating period the content and percentage of particle mercury Hg^T_(p) is higher than soluble mercury Hg^T_(p),but there is not obvious difference between particle and soluble mercury during heating period.The particle mercury Hg⁰_(p) in rainfall plays leading role in migration and transformation of mercury.Heterogeneity phase oxidation of mercury particle may be an dominant process for species transformation of atmospheric mercury.Although there is small part of micro particle in rainfall,it adsorbs more than half of mercury in water phase.The total particle mercury is about more than 75% of total mercury in rainfall.