Abstract
Contamination of water and soils is one of grave problems at mining area. Kamioka Mine, one of the largest Zn-Pb mine in Gifu prefecture in Japan, has been the source of heavy metal pollution in Jinzu River. Cd, Pb, Zn, and Fe have been released from an abandoned dump into the Takahara-Jinzu River system, and serious health problem occurred in the down stream areas. Heavy metals, Cd, in particular, is regarded to be the pathogenic substance causing Itai-Itai Disease. The Cd pollution problems have not yet been solved. Some tailing ponds with neutralizing coagulation treatment (slaked lime) are present in the Kamioka Mine. Heavy metal-contaminated wasted water from tailing and dumping areas were discharged into the Takahara River (the upper stream of the Jinzu River). In this study, five dam sediments along the Takahara-Jinzu River were collected, in order to clarify characteristics of sediments with heavy metals. Each sample was analyzed by using an X-ray powder diffractometer (XRD) and an energy dispersive X-ray fluorescence analyzer (ED-XRF) in order to clarify the mineralogical and chemical compositions of the dam sediments. As a result, the sediment from Asaida dam on the upper course of the Kamioka Mine has little Cd, clay minerals and organic matter, whereas Shininotani dam, Jinzu 1st dam, Jinzu 2nd dam, Jinzu 3rd dam in the down stream of the Kamioka Mine have much sludge, smectite and heavy metals, such as Zn and Cd. Smectite and organic matter have been concentrated with heavy metals in the down stream dam sediments of Jinzu River. In this study, arrange of experimental observation has carried out in order to estimate the ability of heavy metals for the purification of water. The results suggest that bioremediation methods using bacteria is effective as a fixing heavy metals. Filamentous bacteria in biofloc selectively accumulated Pb, Zn, and Cd on the surface of cell wall in laboratory experimental system after one week aging. The bacteria have an ability as a bioremediation, play a key role in the fixation of heavy metals in the down stream dam sediments at mining area.
