作　　者： (陈宁）; (周卫健）; (侯小琳）; (范煜坤）; (鲜锋）; (张路远）; (刘起）; (姜旭宏）;

机构地区： 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室陕西省加速器质谱技术及应用重点实验室,西安710061 西安加速器质谱中心,西安710061 中国科学院大学,北京100049

出　　处： 《地球环境学报》 2017年第4期327-339,共13页

摘　　要： 降雨是大气中碘向陆地沉降的最主要方式。通过分析降雨中的^(129)I浓度和^(129)I/^(127)I比值,既可获得研究区域放射性碘的基础数据,也可为认识碘的来源提供基础数据。本工作分析了在西安收集的近1年(2008年4—10月)的降雨的^(129)I的浓度和水平,由于雨水样品中有机碘份额较高,采用NaOH热分解有机碘的方法对其进行了分解,萃取过程的化学回收率达63.3%—74.8%。127I浓度为0.45—14.10μg?L-1,^(129)I浓度为(1.18—48.91)×10~7 atoms?L-1,^(129)I和^(127)I浓度的变化趋势相似,具有随季节变化的特点,春季降雨^(129)I的浓度为(2.49—4.89)×10~8 atoms?L-1,^(129)I/^(127)I比值为(7.3—9.8)×10^(-9),夏、秋季降雨^(129)I的浓度为(1.18—7.32)×10~7 atoms?L^(-1),^(129)I/^(127)I比值为(1.2—12.0)×10^(-9),春季(4—5月)^(129)I、^(127)I浓度出现一个峰值,可能是由于春季降雨量少,大气中的^(127)I、^(129)I能够积累较长时间,之后通过湿沉降从大气中被去除。西安地区2008年降雨^(129)I的浓度及水平,与国际上已报道的不同地区雨水的^(129)I浓度和水平比较,处于较低水平,主要原因是我国及周边没有正在运行的大型核燃料后处理厂。西安降雨^(129)I/^(127)I比值总体上高于我国沿海海水和以海水中碘为主要来源的海藻,这一特征比值提示了西安降雨中的碘与我国沿海海水中的碘的来源存在差异。 Background, aim, and scope Precipitation is the main pathway for iodine transferring from the atmosphere to soil. Analyzing of 129I concentration and 129I/127I atomic ratio of rain samples is important for obtaining basic data of radioiodine in the study area, as well as the data which are helpful for understanding the source of iodine in precipitation. Materials and methods Rain samples collected in Xi＇an during the period of April to October, 2008 were prepared by solvent extraction method. Due to the high fraction of organic iodine in the rain samples, addition of NaOH and heating were used for converting the organic iodine to inorganic iodine, and the chemical recovery rate of the solvent extraction varied from 63.3% to 74.8%. 129I/127I atomic ratio of rain samples were measured in Xi＇ an AMS Center. Results 127I concentration of rain samples collected in Xi＇an during April to October, 2008 vary from 0.45 μg· L -1 to 14.10 μg· L-1, 129I concentration of these samples vary from 1.18 × 10^7 atoms· L- 1 to 48.91 × 10^7 atoms· L- 1. Variation trend of 129I and 127I concentration are similar. Seasonal variation of these values is observed. 129I concentration in rain samples collected in spring vary from 2.49× 10^8 atoms·L-1 to 4.89×10^8 atoms· L-1, and 129I/127I of these samples vary from 7.3×10 ^-9 to 9.8×10^-9. 129I concentration in rain samples collected in summer and autumn vary from 1.18× 10^7 atoms·L-1 to 7.32× 10^7 atoms＂ L-1, and 129I/127I of these samples vary from 1.2×10 ^-9 to 12.0×10^-9. Discussion High concentration of 129I and 127I of rain samples collected in spring （April--May） occurs, which is possibly attributed to the lower frequency of local rain events in spring, iodine isotopes could accumulate for a long period in the atmosphere, and then be removed from the atmosphere by the precipitation. 129I/1271 atomic ratio of rain samples collected in Xi＇an is higher than those in seawater samples and seaweed samples from the coastal area of China, indicating the diffe

关 键 词： 西安加速器质谱 样品制备 雨水 核环境安全