Heavy Metal Pollution of Soil and Risk Alleviation Methods Based on Soil Chemistry

摘要

In Japan, rapid industrialization during the 1960s brought about dangerous pollution of soil by heavy metals such as cadmium (Cd). Similar heavy metal pollution may occur in other Asian countries that are undergoing rapid development and economic growth, which suggests that these countries will need to regulate heavy metals and institute countermeasures against heavy metal pollution. In this paper we present an overview of soil contamination by heavy metals across Asia, including Japan, paying particular attention to Cd contamination. We present standard values for heavy metal pollution set by various Asian countries. We also describe sources of heavy metal pollution in agricultural soils and summarize the chemical forms of heavy metals in soils. Inaddition, we discuss two promising soil chemistry-based remediation methods for minimizing the risk of Cd contamination: (1) water management practices to reduce the bioavailability of soil Cd to rice plants and (2) remediation of Cd-contaminated soil by soil washing with solutions of chemicals such as iron salts.