地球環境中のイオウと微生物: 人間活動と環境地質学の接点(<特集>環境地質学)

フォーマット:

論文

責任表示:

Tazaki, Kazue ; 田崎, 和江

言語:

英語

出版情報:

地学団体研究会 The Association for the Geological Collaboration in Japan (AGCJ), 1993-05-25

著者名:

• Tazaki, Kazue
• 田崎, 和江

掲載情報:

地球科学 = Earth Science

ISSN:

0366-6611      
2189-7212      

巻:

47

通号:

3

開始ページ:

251

終了ページ:

270

バージョン:

publisher

概要:

金沢大学理工研究域地球社会基盤学系<br />Because of increasing population, human activity has become a dominant process modifying the earth environment. Understanding the new environmental stresses includes study of interface processes on macro- and mi … cro-scales. Application of electron microscopy to the study of sulfides and sulfate complexes in atmospheric dust, in acidic river sediment, in sewage sludge and in water solution, provide unique information on the interaction between bacteria and human activities in close-to-environmental conditions. Microorganisms exhibit great powers of trace metal accumulation and immolization. They may be frequently encountered in extreme metal contaminated environment both natural and man-made. The sulfides leading to the formation of sulfide minerals were observed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy-dispersive X-ray analysis (EDX). For example: 1 Atmospheric sulfide minerals in air dust, 2 Sulfides precipitation with bacteria in polluted mining river sediment, 3 Sulfide mineralization in sludge, 4 Experimental sulfide mineralization in 9 K medium. Atmosphere oxidation rate of SO2 is largely balanced by exchange across the hydrosphere-biosphere-land surface interfaces. Fluctuating volcanic emissions or Chinese loess may have profound influence. SEM-EDX observation indicated that the air dust and acid rain-water contained gypsum, barite and sulfur films which may be due to contributions from volcanic eruption. TEM observation showed bacteria with S-rich thin films in dust of rain-water suggesting interaction between polluted S-rich precipitation and bacterial activity in atmospheric environment. The study of acidic river sediment indicates the enormous influence of the biosphere in maintaining river chemistry of sulfate complexes and sulfides. The electron microscopic techniques enable us to examine the reactive surface at the micron scale, the surface where reaction occurs, that control so many of the basic biogeochemical processes. Micro-scopic study showed that all biomass contains a significant quantity of metallic constituents, and mineralization in living and dead biodebris may contribute to sulfides transport from the hydrosphere into sediment. The bacterial cell walls are remarkable in their ability to fix metals and provide sites for nucleation and growth of Mn, Fe, Cu and Zn minerals. The sulfate complexes and sulfides in sludge in Lake Nakaumi were investigated, including study on the formation of minerals and uptake of metals by bacteria or plant. SEM-EDX observation showed that pyrite, pyrrhotite and gypsum were formed on the top of surface sludge. The aggregate of framboidal pyrite gradually grew in diatom shell which composed of S and Fe, suggesting the processes of sulfide mineral formations related with organisms. The sewage sludge is a valuable source of N, P, and heavy metallic elements (e. g. , Cu, Fe, Mn, Zn) and organic matter. Such metals are of environmental concern due to their potential effects on plant uptake and growth. Jarosite used in the laboratory study was produced from a mixture of 9 K medium and Thiobacillus ferroxidans for a period of several days. SEM-EDX observation with XRD showed that jarosite was formed after 3 days and ammoniojarosite was formed after 7 days from the experimental solution. If T. ferroxidans is present, jarosite can be formed at room temperature by aerating solutions of FeSO4, and K2SO4 at pH 2 within few days. Elemental sulfur interacted with the metal-loaded bacterial cells, affected both the eventual earth science and crystal habit of the metal sulfides, and formed a variety of crystalline metal sulfides. Observation of sulfate complexe changes is unique opportunity to better manage all our earth environment. 続きを見る

URL:

http://hdl.handle.net/2297/00061696