封闭垃圾填埋场通过地表向大气释放汞的测定

利用动力学通量箱及自动测汞仪联用技术,于2004年3月中旬对贵阳市的一座封闭生活垃圾填埋场汞通过地表向大气释放的过程进行了研究。3个采样点的汞释放通量日均值分别为559.1、88.2、53.6ng·m-2·h-1,汞释放通量强度与表层基质中的汞含量密切相关,该测定值高于世界背景地区通量的1~2个数量级,说明封闭垃圾填埋场也是大气汞的潜在来源。汞释放通量呈现明显的昼夜变化规律,白天较高并在午间前后达到最大,而夜间降至最低。气相因子中光照强度与汞的释放过程相关性最高,其次分别是气温、相对湿度、地温和风速。氧化态汞的光致还原作用是可能垃圾填埋场Hg0生成的主要途径,降雨初期能促进地表汞的释放。

Mercury emissions to atmosphere from the surface cover at a closed municipal solid waste landfill

Using the dynamic flux chamber (DFC) method coupled with automated mercury vapor analyzer technique, the mercury emissions from the surface cover of a closed municipal solid waste (MSW) landfill at the suburb of Guiyang, China, has been meas-ured from March 16 to March 20 in 2004. Daily average Hg fluxes from three sites were 559.1, 88.2, 53.6 ng m-2 h-1, respectively. The magnitude of Hg flux was highly correlated with the mercury content in the upper substrate, and mercury emission levels from the landfill were 1 to 2 orders of magnitude greater than that from background zone, indicating the closed landfills also being a po-tential airborne Hg source. Hg flux exhibited a clearly diurnal pattern, reaching the maximum near midday and the lowest during night. Solar radiation has highest relationship with Hg flux, followed by relative humidity, air temperature, soil temperature and wind speed. Photo-reduction of oxidized mercury (Hg2+) was been assumed to the prominent process in the production of volatile elemen-tal mercury (Hg0). The initial precipitation has stimulated the mercury emissions from the landfill to atmosphere.