砒素の汚染土壌の由来に関する実験的検討―土壌鉱物のＥＰＭＡマッピング分析―

Abstract

Electron Probe Micro Analysis (EPMA) was applied to soil samples which contained high arsenic concentration over soil standard level to identify chemical state and origin of arsenic in the soil. Two dimensional mapping of selected elements including arsenic, iron, sulfur and silicon identified the two types of local distribution of arsenic at high concentration. One type is to contain a high concentration of arsenic, iron and sulfur, indicating the presence of arsenopyrite (FeAsS) in the sample. The other type contained high concentration of iron and arsenic but not with sulfur. The latter seemed to contain iron (III) arsenate which may be secondarily produced through precipitation in the environment after arsenic and iron were dissolved from arsenopyrite by weathering.