Biomineralization in Biomats at Hirayu Hot Springs
| Autor: | Ohno, Motohiro, Tazaki, Kazue |
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| Jazyk: | japonština |
| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | 地球科学 = Earth Science. 54(5):298-309 |
| ISSN: | 0366-6611 |
| Popis: | 金沢大学理工研究域地球社会基盤学系 高温環境である平湯温泉,おばこ原の湯には3種のバイオマット(白色,茶色,緑色)が存在する.これらのバイオマットは水温,pH,Eh,DO,光および温泉水の流れの変化に伴い,上流部から下流部に向かって色調が白色→茶色→緑色へと変化する.白色バイオマットは主として大鎌型細菌から構成され,硫黄を濃集するのに対し,茶色バイオマットは多量の桿菌および少量の糸状菌で構成され,水酸化鉄を濃集する.また,緑色バイオマットは糸状菌から構成され,カルシウムを濃集し,方解石を形成する.すなわち,バイオマットの色は生息する微生物種と形成された生体鉱物を反映している.その中でも高温環境下に存在する大鎌型細菌は夾膜の表面に雁行状に硫黄の結晶を成長させる特徴がある. Colorful biomats were found at Obakoharanoyu in Hirayu Hot Springs, Gifu, Japan. At the upper stream white biomats were commonly found, whereas brown and green biomats occur at the down stream, according to change of environmental conditions, such as temperature, pH, Eh, DO, S2-, photosynthesis and water flow velocities. The pH, WT, Eh, and DO diagrams of the hot spring water from upper to down stream have responded to the occurrence of biomats. White biomats occur in low pH (6.1), reducing (Eh:-270mV), micro-aerobic (DO: 0.3mg/l) and high temperature (70℃) conditions. On the other hand, brown biomats occur in wide ranges of pH (6.5-7.8), Eh (-125〜90mV), DO (2.0〜5.0mg/l) and WT (42-60℃) respectively. In contrast, the occurrence of green biomats are high pH (8.4), oxidizing (Eh: 100mV), aerobic (DO: 7.5mg/l) and middle temperature (30℃). Sulfur ions are detected in water on the white biomats (1-2ppm), while not detected from both brown and green biomats. The white biomats comprising sausage shaped bacteria contain abundant sulfur. The green biomats consist of filamentous bacteria with abundant calcite. The results have revealed that the color of biomats reflects the environmental conditions. TEM and SEM observations indicate that sulfur particles adhere to capsule on the cell wall of sausage shaped bacteria in white biomats. The sulfur particles might be grown to a-sulfur crystals of 10μm insize. The results have revealed that sulfur-biomineralization of sausage shaped bacteria in white biomats is a very important factor for sulfur removal in hot springs. |
| Databáze: | OpenAIRE |
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