Transmission electron microscopic observation of mercury-bearing bacterial clay minerals in a small-scale gold mine in Tanzania

フォーマット:

論文

責任表示:

Tazaki, Kazue ; Asada, Ryuji

言語:

英語

出版情報:

Taylor & Francis, 2007-09-01

著者名:

• Tazaki, Kazue
• Asada, Ryuji

掲載情報:

Geomicrobiology Journal

ISSN:

0149-0451      

巻:

24

通号:

6

開始ページ:

477

終了ページ:

489

バージョン:

author

概要:

金沢大学大学院自然科学研究科環境動態<br />Mercury is a toxic substance that is widely distributed throughout the hydrosphere, biosphere, and lithosphere. Mine waste environments and mine waters support a wide diversity of microbial life. The microbial … ecology of environments where mine waters are polluted with heavy metals is poorly understood. Here, we describe the features of bacteria in mercury-contaminated gold panning ponds in a small-scale gold mine (Geita) near Lake Victoria, Tanzania using energy filtering transmission electron microscopy (EF-TEM) and scanning transmission electron microscopy equipped with energy dispersive X-ray spectroscopy (STEM-EDX). Most bacteria in the panning pond showed thick exopolysaccharides (EPSs), and many clay minerals attached onto the surface of EPSs. The clay minerals and EPSs might act as protective layers for the bacteria against toxic materials. The clay minerals were composed of smectite, halloysite, and kaolinite associated with calcite and goethite. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy indicated that the bulk soil samples contained abundant Si, Al, K, Ca, and Fe with heavy metals such as Au, Ti, and Ag. The results indicate that Hg pollution from panning ponds is caused by not only volatilization of Hg from Au-Hg amalgams, but Hg is also released into the air as dust mixed with dry fine clays, suggesting high long-term environmental risks. Mercury-resistant bacteria associated with clay minerals may have a significant effect on the weathering processes of the ore during long-term bioremediation. The clay mineral complexes on the surface of bacterial cell walls are a stimulator for Hg-resistant bacterial growth in mud ponds contaminated with the Au-Hg materials.　全文公開200809 続きを見る

URL:

http://hdl.handle.net/2297/7369