土壤中Cd、Pb、Hg离子的地球化学行为模拟实验

    Simulation experiment on the geochemical behavior of cadmium, lead and mercury ions in the soil. Geological Bulletin of China

    • 摘要: 研究了山西省3种不同质地的土壤对Cd2+、Pb2+、Hg2+的吸附、解吸和3种离子在土壤中的运移特性。结果表明,Cd2+、Pb2+和Hg2+在粘粒土壤中的吸附能力大于在砂粒土壤中的吸附能力,且3种土壤对Pb2+都有很强的吸附能力,吸附的Pb2+很难在土壤中解吸下来。3种土壤对3种金属离子的吸附能力为Pb2+>Cd2+>Hg2+,解吸能力正好相反,这主要与土壤的不同性质和3种重金属离子的水合离子半径、离子的水合能密切相关。Cd2+在3种土壤中的等温吸附符合Freundlich和Langmuir方程,Pb2+在3种土壤中的吸附特征符合Henry方程,而Hg2+在3种土壤中的吸附符合Langmuir方程。土柱淋滤实验表明,Hg2+在土壤中的穿透性很强,Cd2+次之,Pb2+在土壤中的穿透性最慢,其在长达20天的淋滤过程中仍然没有穿透土柱。3种不同质地的土壤对Cd2+、Pb2+和Hg2+的迁移能力都表现为:大同土壤>临汾土壤>太原土壤。

       

      Abstract: Adsorption, desorption and transportation experiments of Cd2+, Pb2+ and Hg2+ in three different kinds of soil in Shanxi Province were studied in this paper respectively. Results show that the adsorption capacity of Cd2+, Pb2+ and Hg2+ were all higher in clay-sized soil than that of sand-sized soil. Meanwhile, all these soils have strong adsorption capacity for Pb2+, which was very difficult to desorb. The adsorption capacity of the three heavy metal ions in all three kinds of soil decreased in an order of Pb2+>Cd2+>Hg2+, whereas the desorption capacity is just opposite. This was mainly due to the close correlation of sorption capacity with different soil properties, hydration energy and hydration iron radius of metal ions. The isothernal adsorption of Cd2+ conformed to the Freundlich and Langmuir equation in different soils, the Henry equation was suitable for the Pb2+ adsorption, and the Langmuir equation for Hg2+. According to the soil column leaching test, penetration ratio of Hg2+ through soils is highest, secondly Cd2+and Pb2+ is lowest which doesn′t pass the column after 20 days leaching. The transport capacity of three different kinds of soil texture for Cd2+, Pb2+and Hg2+decreased in the order of Datong soil, Linfen soil and Taiyuan soil.

       

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