土壤中Hg离子地球化学行为模拟实验--以山西的典型土壤为例

Simulation experiment of the geochemical behavior of Hg in soils—A case study of typical soils in Shanxi,China

土壤样品分别采于山西省大同、太原和临汾3个地区。实验分成吸附解吸实验和运移实验2个部分。其中吸附实验分成砂粒土壤和粘粒土壤2个粒级分别进行。结果表明:3种土壤对Hg的吸附量随着加入Hg离子溶液浓度的增加而增加。用4种吸附模式来拟合3种土样对Hg的吸附可以得出,Freundlich模式和Langmuir模式能较好地拟合3种土壤对Hg吸附的实验数据。3种土壤对Hg都有一定的吸持固定作用。解吸率由大到小依次为大同土壤>临汾土壤>太原土壤。当Hg2+的浓度为300mg/L时,Hg在大同土壤中的穿透速率最快,在太原土壤中穿透速率最慢。从而得出Hg2+在壤质砂土中运移速度最快、在粉壤土中运移速度最慢的结论。

Soil samples were taken from Datong, Taiyuan and Linfen. The experiment comprised two parts： adsorption-desorption and transport experiment. Soils for the adsorption experiment were sieved into the sand-sized fraction and clay-sized fraction. The main results indicate that the amount of Hg absorbed by the three kinds of soil increased with increasing equilibrium concentration of Hg ion solution. The adsorption of Hg by the three types of soil was fitted by four adsorption models at normal temperature and pressure, of which the Freundlich mode and Langmuir model can better fit the experimental data of Hg adsorption by the three kinds of soil, all of which have a certain retaining and fixation effect on Hg. The soils in order of decreasing desorption rates are the Datong soil, Linfen soil and Taiyuan soil. When the concentration of Hg^2＋ is 300 mg/L, the rate of Hg penetration through the Datong soil is highest and that through the Taiyuan soil is lowest. Consequently the authors conclude that Hg^2＋ is transported most rapidly in loamy sand and most slowly in silty loam.