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尾瀬ヶ原に現れるアカシボと鉄・マンガン酸化細菌
横山, 亜希子;滝, 玲加;大鐘, 由加子;八木, 明彦
Permalink : http://hdl.handle.net/2115/49043
KEYWORDS : アカシボ;鉄酸化細菌;低温培養;Akashibo;Iron oxdation bacteria;Low-temperature Bacterial culture
Abstract
尾瀬ヶ原にて5月の融雪時に雪の表面が赤褐色化する現象を地元の人はアカシボと呼んでいる. 尾瀬ヶ原は泥炭質で, 鉄はフミン質などと錯体を形成し, 地下水に溶存態鉄として豊富に含まれている. この溶存態鉄が酸化され懸濁態鉄になる過程がアカシボ現象に作用していると考えられる. このアカシボ現象を鉄・マンガン酸化細菌の面から解明することを目的とした. 室内実験にて, 鉄酸化細菌を20℃, 4℃, 0℃で培養し, 溶存態鉄の減少に伴い懸濁態鉄の増加, 溶存性有機物減少, 細菌数増加の経日変化がみられた. このことから雪や融雪中の低温環境においても鉄酸化細菌は強い酸化力をみせ, アカシボ現象の要因の一つであることが考えられた.
Akashibo is a name people in the area use to describe a phenomenon by which the surface of snow acquires a reddish-brown-black color in the snowmelt in May of every year. People in the area call it Akashibo. Dissolved iron is richly contained in the groundwater of Ozegahara. Our objective was to explain this Akashibo phenomenon by the contribution of the iron and manganese oxidation bacteria. From our laboratory experiments, iron oxdation bacteria were cultivated at 20 ℃, 4 ℃, and 0 ℃. As a result, the particulate iron and bacteria increased and the dissolved iron decreased with the decrease of the dissolved organic carbon. The Akashibo phenomenon is regarded as dependent on the involvement of the bacteria by which iron oxidation is actively carried out even at low temperatures.
Akashibo is a name people in the area use to describe a phenomenon by which the surface of snow acquires a reddish-brown-black color in the snowmelt in May of every year. People in the area call it Akashibo. Dissolved iron is richly contained in the groundwater of Ozegahara. Our objective was to explain this Akashibo phenomenon by the contribution of the iron and manganese oxidation bacteria. From our laboratory experiments, iron oxdation bacteria were cultivated at 20 ℃, 4 ℃, and 0 ℃. As a result, the particulate iron and bacteria increased and the dissolved iron decreased with the decrease of the dissolved organic carbon. The Akashibo phenomenon is regarded as dependent on the involvement of the bacteria by which iron oxidation is actively carried out even at low temperatures.
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