天然水体中总α和总β放射性来源分析

Analysis of the origination of grossαand grossβin natural waters

天然水放射性源自溶于水中的放射性核素。总α和总β放射性能够反映各类水体放射性总体水平,是水质辐射监测的筛选指标。原生放射性核素如铀系、钍系衰变系列核素和独立长寿命核素^(40)K等是天然水放射性的主要来源;^(238)U、^(235)U和^(232)Th三个天然衰变系以α衰变为主,β衰变只占小部分;^(40)K的β衰变过程常常是水中总β放射性的主要贡献者。20余种宇生放射性核素中除了^(3)H和^(14)C以外,其他浓度都很低,干湿沉降作用和光合作用可以使^(3)H和^(14)C迁移进入地球圈层并进入天然水中。遇酸遇热不稳定的、易挥发的、半衰期短的放射性核素不能被低本底测量方法有效测定,没有呈现在最终的表观总α和总β活度浓度结果中。单一放射性核素的测量需要采用特定的采样保存技术和分析方法。

Natural water radioactivitywas derived from radionuclides dissolved in water.Grossαand grossβradioactivity can reflect the overall radioactive level in various water bodies andwerescreening indicators for water quality radiation monitoring.Primordial radionuclides such as uranium,thorium decay series nuclides and independent long-lived nuclide^(40)K werethe major sources of natural water radioactivity.αdecay dominates in the three natural decay series of^(238)U,^(235)U and^(232)Th,andβdecay was only a small part.Theβdecay process of^(40)Kwas usually the main contributor of grossβin natural waters.Except for^(3)H and^(14)C,other 20 cosmogenic radionuclides were at low levels.^(3)H and^(14)C can enter the Earth’sphere through dry and wet deposition and photosynthesis and exist in natural waters.The radionuclides which was unstable to acid and heat,volatile and short half-life cannot be effectively determined by low-background measurement method and were not presented in the final apparent gross radioactive concentration results.The measurement of a single radionuclide requires specific sampling and preservation techniques and analytical methods.