A Study on the Retention and Transport Mechanism of Heavy Metals in Volcanic Clayey Soils.

在室内试验的基础上，研究了重金属在火山粘性土中的滞留和迁移机制。日本火山粘土堆积面积大，重金属是工业废物处理渗滤液中通常含有的有害物质。用浓度为1 mg/L~20 mg/L的铜离子(Cu2+&lt；2+)和铅离子(Pb2+&gt；)研究了它们在土壤孔隙中的滞留特性和迁移机制。两种离子的保留特性均表现为非线性吸附，吸附速率随溶质浓度的增加而减小，可用Freundlich或Langmuir型吸附函数表示。随后，通过柱试验进行流动分析，研究了饱和土壤中重金属离子溶液的对流-弥散特性，通过将考虑离子在土壤中的保留特性的迁移方程与实验获得的穿透曲线进行比较，评估了弥散系数和衰减系数等性质。结果表明，火山粘性土中重金属离子的分散度为2~4 cm，衰减系数为3.5~13.0。最后，对重金属渗漏对地面环境造成的污染进行了计算机模拟。

Laboratory experiments based on the column tests were carried out to investigate the retention and transport mechanism of heavy metals in volcanic clayey soils. The volcanic clayey soils are accumulated over a wide area in Japan, and the heavy metals are the hurtful substances which normally contained in the percolated solutions from the industrial waste disposals. The copper ion (Cu^<2+>) and the lead ion (Pb^<2+>) of the concentration of 1mg/L〜20mg/L were used to examine their retention characteristics and the transport mechanism in soil pores. The retention characteristic of both ions showed nonlinear adsorption in which the rate of adsorption decreases as the solute concentration increases, and the characteristics can be expressed by the Freundlich-type or Langmuir-type adsorption functions. Subsequently, the flow analysis by column tests was made to investigate the advection-dispersion characteristics of heavy metal ion solutions in saturated soils.The properties such as dispersion coefficients and decay coefficients were evaluated by comparing the transport equation incorporating the retention characteristics of the ions in soil to the experimentally obtained breakthrough curves. It was shown that the dispersivities of heavy metal ions in the volcanic clayey soils ranged from 2〜4 cm, and the decay coefficients were 3.5〜13.0. Finally, the computer simulation was performed to demonstrate the aspect of ground environmental contamination cased by the leakage of heavy metals.