2012 Volume 50 Issue 3 Pages 144-153
Soil, mineral and clay become recognized as the source of pollution on groundwater and soil contamination at one time or another. Admittedly, groundwater contamination shall be deemed an event related closely to soil contamination, leaching hazardous substances to groundwater. And, the soil containing minerals with naturally-occurring heavy metals often contaminates soil and groundwater with artificial construction such as tunnel excavation. Sulfide minerals such as pyrite and arsenopyrite are thought to be the most likely causative substances of naturally-occurring soil contamination with heavy metals, occasionally leach heavy metals and make soil acidification after oxidizing by air and microbial activity. And then, contaminated soils with naturally-occurring heavy metals are identified into 3 classes and 2 leaching types with disposition about leaching of heavy metals and pH change. On the one hand minerals and soils are cause of contamination, but on the other hand minerals kindred class of clay are environmental-friendly materials to countermeasure of groundwater and soil contamination. There are mainly classed 8 types, clay minerals like smectite, allophane, zeolite, aluminum minerals, iron minerals, minerals containing calcium or magnesium, cement minerals and layered double hydroxide. The countermeasure technique such as immobilization and permeable adsorption layer using their minerals comes into wide use with acceptance. However, the countermeasure material was occasionally seen as ineffective against the contaminated substance from a lack of the comprehension about interaction mechanism between heavy metals and minerals, even if it is not used in effectual condition on the soil contamination site at that time. Therefore the activity for understanding to mineral interaction becomes recently promoted to get rid of such a blundering trouble.
