Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, United States.
Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, United States.
J Hazard Mater. 2018 May 15;350:19-26. doi: 10.1016/j.jhazmat.2018.02.006. Epub 2018 Feb 6.
Nitrate and radioiodine (I) contamination is widespread in groundwater underneath the Central Plateau of the Hanford Site. I, a byproduct of nuclear fission, is of concern due to a 15.7 million year half-life, and toxicity. The Hanford 200 West Area contains plumes covering 4.3 km with average I concentrations of 3.5 pCi/L. Iodate accounts for 70.6% of the iodine present and organo-iodine and iodide make up 25.8% and 3.6%, respectively. Nitrate plumes encompassing the I plumes have a surface area of 16 km averaging 130 mg/L. A nitrate and iodate reducing bacterium closely related to Agrobacterium, strain DVZ35, was isolated from sediment incubated in a I plume. Iodate removal efficiency was 36.3% in transition cultures, and 47.8% in anaerobic cultures. Nitrate (10 mM) was also reduced in the microcosm. When nitrate was spiked into the microcosms, iodate removal efficiency was 84.0% and 69.2% in transition and anaerobic cultures, respectively. Iodate reduction was lacking when nitrate was absent from the growth medium. These data indicate there is simultaneous reduction of nitrate and iodate by DVZ35, and iodate is reduced to iodide. Results provide the scientific basis for combined nitrogen and iodine cycling throughout the Hanford Site.
硝酸盐和放射性碘（I）污染广泛存在于汉福德场地中央高原的地下水之下。I 是核裂变的副产品，由于半衰期为 1570 万年，且具有毒性，因此备受关注。汉福德 200 西区域的污染羽覆盖了 4.3 公里，平均 I 浓度为 3.5 皮居里/升。碘酸盐占存在碘的 70.6%，有机碘和碘化物分别占 25.8%和 3.6%。包含 I 羽流的硝酸盐羽流的表面积为 16 公里，平均硝酸盐浓度为 130 毫克/升。从碘羽流沉积物中分离出一种与根瘤农杆菌密切相关的硝酸盐和碘酸盐还原菌，菌株 DVZ35。在过渡培养物中，碘酸盐的去除效率为 36.3%，在厌氧培养物中为 47.8%。微宇宙中也还原了硝酸盐。当硝酸盐被加入微宇宙时，过渡和厌氧培养物中的碘酸盐去除效率分别为 84.0%和 69.2%。当生长培养基中没有硝酸盐时，碘酸盐的还原就会缺失。这些数据表明，DVZ35 可以同时还原硝酸盐和碘酸盐，并且碘酸盐被还原为碘化物。这些结果为整个汉福德场地的氮和碘循环提供了科学依据。
