Heavy metal concentrations, leachabilities and lead isotope ratios of Japanese soils

摘要

Soil Contamination Countermeasures Law (referred to hereafter as the Law) was made on 29 May 2002, for preventing health damage which toxic substances as Pb, As, Cr(VI) and Cd in soils could cause by oral ingestion. In order to carry out the Law, we must judge whether soils have high toxic metal concentrations or high leachabilities caused by anthropogenic or natural processes. If high toxic metal concentrations or high leachabilities are caused by natural processes, the administration of the Law should not oblige landowners, managers and occupiers of contaminated sites to remedy them. Therefore, it is essential to determine natural levels of Pb, As, Cr(VI) and Cd concentrations and their leachabilities of Japanese soils which have a wide range of chemical and mineralogical composiotion. It is also very important to develop chemical and mineralogical analytical methods to judge whether soils have high toxic metal concentrations or high leachabilities caused by anthropogenic or natural processes. We obtained Pb, As, Cr(VI) and Cd concentrations and leachabilities of stream and marine sediments, as well as soils formed by weathering of volcanic ashes and granite and granitoid, using XRF and conventional wet chemical analytical methods. We also obtained mineralogical data of these sediments and soils, using XRD, TG-DTA and analytical TEM. Furthermore, we obtained lead isotope ratios of these sediments and soils, using ICP-Mass.