Contamination by toxic substance of soil and groundwater originating ina great earthquake disaster

研究了阪神旭日大地震引发的大火对城市公园土壤造成重金属污染的可能性。采用不同的提取方法，研究了灾区公园土壤中重金属的行为和重金属吸附形态的时间变化。得出以下结论：1.部分重金属在时间上从交换态转变为盐酸萃取态，最后转变为硝酸不可萃取态。锌和锑被提名为地震灾害期间传播的元素，因为它们在受大火影响显著的永田区土壤中含量较高。锌和锑的最高浓度分别比京都和横滨高出几倍。其他一些重金属显示出另一种可能性，即正常的城市活动对它们的污染。铬-铜、铬-铅、锰-钴、钴-铜、钴-锌、钴-铅、铜-镉、铜-铅等元素对的相关系数呈时间递减趋势，而锰-铜、锰-锌、锰-镉、锰-铅元素对的相关系数呈时间递增趋势。这意味着土壤中这些金属的缓慢再分配导致了它们之间相关系数的变化。聚类分析也清楚地表明了这种可能性。这项研究的结果可以与已报道的关于空气和降雨的调查结果进行比较。

The possibility of heavy metal contamination of urban park soils caused by a big fire originating in the Great Hanshin Awaji Earthquake was examined. The behavior of heavy metals in park soil of the stricken area and the change in time of sorption forms of heavy metals were studied with various extraction methods. The following conclusions were obtained :1. Some heavy metals temporally changed their sorption forms from exchangeable forms to hydrochloric acid extraction forms, and finally to the forms unextractable even by nitric acid.2. Zn and Sb were nominated for the element spread during the earthquake disaster, because they showed high concentration in soil in the Nagata district where the influence of the big fire was significant. The highest concentrations of Zn and Sb were some times larger than those in Kyoto or Yokohama respectively. Some of the other heavy metals showed another possibility of their contamination by the normal urban activities.3. The correlation coefficients of the couples of elements, I.e. Cr-Cu, Cr-Pb, Mn-Co, Co-Cu, Co-Zn, Co-Pb Cu-Cd, and Cu-Pb, showed temporally decreasing trends, however, those of the couples of Mn-Cu, Mn-Zn, Mn-Cd, and Mn-Pb showed temporally increasing trends. This meant that the slow repartitioning of those metals in soil caused the changes of correlation coefficients of them. The cluster analyses also showed this possibility clearly.4. The results of this study could be compared to the reported investigation results about air and rain.