Ability of anaerobic microorganisms to associate with iodine: 125I tracer experiments using laboratory strains and enriched microbial communities from subsurface formation water
Ability of anaerobic microorganisms to associate with iodine: 125I tracer experiments using laboratory strains and enriched microbial communities from subsurface formation water
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DOI：
10.1016/j.chemosphere.2010.02.028
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发表时间：
2010-04-01
期刊：
影响因子：
8.8
通讯作者：
Fukunaga, Sakae
中科院分区：
文献类型：
--
作者：
Amachi, Seigo;Minami, Keiichiro;Fukunaga, Sakae
碘-129（I-129）是一种裂变产物，半衰期为1570万年。由于I-129具有半衰期长、迁移率高、对人体亲和力强等特点，被认为是核废物深部地质处置中最具争议的放射性核素之一。在这项研究中，16株厌氧微生物，包括硝酸盐还原菌，铁还原菌，硫酸盐还原菌，产甲烷菌，厌氧培养与放射性碘示踪剂（I-125），以确定他们是否具有与碘的能力。我们通过测定培养物上清液中I-125活性的降低来确定结合效率，从而对其进行评价。结果发现，约一半的菌株的效率低于检测限（1.0%），其余菌株的效率在1.0%至6.3%之间变化，但没有统计学意义。利用从日本Minami-kanto气田收集的富碘地下地层水中的厌氧微生物群落进行了类似的实验。微生物群落对碘的特定吸收估计为0.71-2.0 μ g g（-1）生物量干重，表明缔合能力（如果存在）非常有限。这些结果表明，厌氧微生物，与好氧微生物相比，既不提高也不抑制的流动性的I-129，在这种放射性核素从处置设施排放到周围环境的情况下。(C)2010爱思唯尔有限公司保留所有权利。
Iodine-129 (I-129) is a fission product with a half-life of 15.7 million years. Because of its long half-life, high mobility, and high affinity to the human body, I-129 is considered as one of the most problematic radionuclides in nuclear waste disposals in deep geological formation. In this study, 16 strains of anaerobic microorganisms, including nitrate-reducing bacteria, iron-reducing bacteria, sulfate-reducing bacteria, and methanogens, were cultured anaerobically with a radioiodine tracer (I-125) to determine whether they possess the ability to associate with iodine. We evaluated it by association efficiency, that was determined by measuring the decrease in I-125 activity in the culture supernatant. It was found that the efficiency of about half of the strains was below detection limit (1.0%), and that of the remaining strains varied from 1.0% to 6.3%, although it was not statistically significant. Similar experiments were conducted by using anaerobic microbial communities inhabiting the iodine-rich subsurface formation water collected from the Minami-kanto gas field in Japan. The specific uptake of iodine by the microbial communities was estimated to be 0.71-2.0 mu g g(-1) dry weight of biomass, indicating that the association ability was, if present, very limited. These results suggest that anaerobic microorganisms, in contrast with aerobic microorganisms, neither enhance nor repress the mobility of I-129, in the case of discharge of this radionuclide from disposal facilities into the surrounding environment. (C) 2010 Elsevier Ltd. All rights reserved.