Evaluation and Technical Control of Soil Contamination by Heavy Metals

城市土壤中有毒重金属的分布和迁移对人类健康、农业和生态系统的影响具有重要意义。本研究的目的由四个部分组成。首先是通过调查城市固体垃圾焚烧厂和神户市周围表层土壤中元素的浓度来确定值得注意的化学沉降物元素。二是提出了非饱和土壤中重金属动态特性的评价方法。三是提出了控制土壤水分和污染物在土壤中运动的方法——斜坡粗土屏障。第四，提出了选择合适的土壤污染技术控制方法的指导原则。得到了以下一些有价值的结果。(1)测定了大地震破坏的城市生活垃圾焚烧厂附近和神户市周边土壤中元素的垂直分布。原子吸收光谱（INAA）、电感耦合等离子体原子发射光谱（ICP-AES）测定元素浓度。结果表明，Zn、Sb、Br是城市生活垃圾焚烧厂产生的化学沉降物中的重要元素，而Cr、Co、Ni、Cu、Zn、as、Cd、Sb、Pb可能是阪神-浅路大地震后大火产生的地表土壤中添加的元素。(2)采用非饱和土柱试验，评价含水量对土壤对钴吸附-解吸反应的影响。砂和粉土中钴的分布系数在一定含水量下均有最小值。(3) 60cm ~ 480cm（宽度）尺度的模型和数值试验表明，坡面粗土屏障有效地控制了土壤水分的向下运动。60cm-480cm（宽度）尺度的模型和数值实验。这种屏障的有效性主要取决于规模、降雨强度和持续时间。

Distribution and migration of toxic heavy metals, which have been added into urban soil, are of great interest to assess its effect on the human health, agriculture, and ecosystems. The purposes of this study are consist of four parts. The first is to identify notable elements as chemical fallout by surveying concentrations of elements in surface soil around municipal solid waste incineration plant and Kobe City. The second is to propose the method to evaluate dynamic behavior of heavy metal in unsaturated soil. The third is to propose the method for control the soil water and contaminant movement in soil, named sloped coarse-soil barrier. The fourth is to propose a guideline for selecting an appropriate technical control method of soil contamination. Some valuable results were obtained as follows.(1) The vertical distribution of elements were measured in the soils sampled in the vicinity of municipal solid waste incinerators plant and around Kobe City damaged by great earthquake. elements concentrations were determined by INAA,ICP-AES.From these measurement, it was suggested that Zn, Sb, and Br were notable elements as chemical fallout derived from the municipal solid waste incinerators plant, and Cr, Co, Ni, Cu, Zn, As, Cd, Sb, Pb were possibly added to surface soil derived from big fires after Hanshin-Awaji Great Earthquake.(2) Unsaturated soil column experiments were carried out to evaluate the effects of water content on the sorption-desorption reaction of cobalt by soil. The estimated distribution coefficients of cobalt have minimum value at a certain water content for both sand and silt.(3) From model and numerical experiments of 60cm-480cm (width) scale, it was indicated that downward soil water movement was effectively controlled by sloped coarse-soil barrier. at model and numerical experiments of 60cm-480cm (width) scale. The availability of this barrier mainly depends on the scale, rainfall intensity, and its duration.