Robison William L, Hamilton Terry F
Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, 7000 East Avenue, L-453, Livermore, CA 94550-9234, USA.
Health Phys. 2010 Jan;98(1):1-11. doi: 10.1097/HP.0b013e3181b9dbd3.
Radiation doses calculated for people resettling Bikini Island at Bikini Atoll, Enjebi Island at Enewetak Atoll, Rongelap Island at Rongelap Atoll, and Utrōk Island at Utrōk Atoll are presented. Residence is assumed to begin in 2010. In previous dose assessments it was shown that (137)Cs accounts for about 98% of the total dose for returning residents. About 85 to 90% (depending on the atoll) is via consumption of locally grown foods containing (137)Cs, and about 10 to 15% is due to external exposure from (137)Cs in the soil. These assessments were made using only the radiological half-life of (137)Cs (30.1 y). We have shown since that there is an environmental loss of (137)Cs from soil to groundwater that results in a more rapid loss of (137)Cs from the atoll ecosystem. The mean effective half-life of (137)Cs at the atolls is 8.5 y. Moreover, treatment of coconut trees with potassium (K) reduces (137)Cs concentration in drinking coconut meat at Bikini Atoll to about 5% of pretreatment concentrations. The magnitude of reduction is dependent on the concentration of (137)Cs in soil, and thereby in food crops, and is less for Enjebi and Rongelap Islands than for Bikini Island. Treatment of food crops and fruit trees with K and removal of the top 15 cm of soil around houses and community buildings prior to construction to reduce external exposure where people spend most of their time has been presented to the communities as a "Combined Option" remediation strategy. Doses presented here are calculated using the Combined Option, effective half-life of (137)Cs at the atolls, and a diet of both imported and local foods. The average natural background dose in the Marshall Islands, plus the anthropogenic nuclear test-related dose at Bikini, Enjebi, and Rongelap Islands, is less for each of the islands than the average background dose in the U.S. and Europe.
本文给出了为比基尼环礁的比基尼岛、埃内韦塔克环礁的恩杰比岛、朗格拉普环礁的朗格拉普岛以及乌特罗克环礁的乌特罗克岛重新定居的人们计算的辐射剂量。假定居住从2010年开始。在之前的剂量评估中表明，（137）铯占返回居民总剂量的约98%。约85%至90%（取决于环礁）是通过食用当地种植的含（137）铯的食物，约10%至15%是由于土壤中（137）铯的外部照射。这些评估仅使用了（137）铯的放射性半衰期（30.1年）。此后我们表明，（137）铯从土壤到地下水存在环境损失，这导致（137）铯从环礁生态系统中更快地流失。环礁处（137）铯的平均有效半衰期为8.5年。此外，用钾（K）处理椰子树可将比基尼环礁饮用椰肉中的（137）铯浓度降低至预处理浓度的约5%。降低幅度取决于土壤中（137）铯的浓度，进而取决于粮食作物中的浓度，恩杰比岛和朗格拉普岛的降低幅度小于比基尼岛。作为一种“综合方案 ”修复策略，已向社区介绍了用钾处理粮食作物和果树以及在建造房屋和社区建筑之前清除房屋周围顶部15厘米的土壤以减少人们大部分时间所在处的外部照射的方法。此处给出的剂量是使用综合方案、环礁处（137）铯的有效半衰期以及进口和当地食物的饮食计算得出的。马绍尔群岛的平均天然本底剂量，加上比基尼岛、恩杰比岛和朗格拉普岛与人为核试验相关的剂量，每个岛屿的剂量都低于美国和欧洲的平均本底剂量。
