Distribution Features of 238U, 232Th, and 226Ra in Bottom Sediments of the Shelf and Continental Slope of Svalbard

IF 0.9 Q4 CHEMISTRY, INORGANIC & NUCLEAR Radiochemistry Pub Date : 2024-04-23 DOI:10.1134/s1066362224010144

M. M. Domanov

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Abstract

The features of the concentration distribution of ²³⁸U, ²³²Th, and ²²⁶Ra in the surface layer in the bottom sediments of the shelf and continental slope of Svalbard are considered. The content of ²²⁶Ra, ²³²Th, and ²³⁸U varied in the range 22–134.3, 22.4–50.9, and 10.9–37.7 Bq/kg, respectively. The amount of ²²⁶Ra nonequilibrium with ²³⁸U (²²⁶Ra_ex) ranged from 23 to 73% of the total ²²⁶Ra content in sediments. The maximum concentrations of ²²⁶Ra, ²³⁸U, ²³²Th, and ²²⁶Ra_ex (134.3, 37.7, 50.9, and 98.2 Bq/kg, respectively) were obtained in the area of increased bioproductivity (Eagle Trough). In this zone, the relationship between the concentrations of ²²⁶Ra and ²²⁶Ra_ex with the content of organic matter in sediment is well expressed, the correlation coefficients are R = 0.94 and 0.92, respectively, which indicates a significant contribution of the biological community to the accumulation of ²²⁶Ra in bottom sediments. The ²²⁶Ra concentration and the ²²⁶Ra excess value are negatively related to the redox potential of the sediment (R = –0.88). This pattern is also true in other areas of the Svalbard waters. In general, for the entire array of observations, the concentrations of ²³⁸U and ²³²Th increase with increasing content of organic carbon in the sediment (R = 0.72 and 0.7, respectively). The concentrations of ²³⁸U and ²³²Th decrease with increasing C_carb content in the sediment (R = –0.79 and –0.81, respectively). The data obtained indicate the need to take into account the ²²⁶Ra excess when assessing the total natural radioactivity of marine sediments, the value of which may exceed the radioactivity of ²³⁸U and ²³²Th.

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斯瓦尔巴群岛大陆架和大陆坡底层沉积物中 238U、232Th 和 226Ra 的分布特征

摘要考察了斯瓦尔巴大陆架和大陆坡底层沉积物表层中 238U、232Th 和 226Ra 的浓度分布特征。226Ra、232Th 和 238U 的含量变化范围分别为 22-134.3、22.4-50.9 和 10.9-37.7Bq/kg。与 238U 非平衡的 226Ra 含量（226Raex）占沉积物中 226Ra 总含量的 23% 至 73%。226Ra 、238U、232Th 和 226Raex 的最大浓度（分别为 134.3、37.7、50.9 和 98.2 Bq/kg）出现在生物生产力增加的区域（鹰槽）。在这一区域，226Ra 和 226Raex 的浓度与沉积物中有机物含量之间的关系表现良好，相关系数分别为 R = 0.94 和 0.92，这表明生物群落对 226Ra 在底层沉积物中的积累有重要作用。226Ra 浓度和 226Ra 超标值与沉积物的氧化还原电位呈负相关（R = -0.88）。这种模式在斯瓦尔巴群岛水域的其他地区也是如此。一般来说，在整个观测阵列中，238U 和 232Th 的浓度随着沉积物中有机碳含量的增加而增加（R = 0.72 和 0.7）。238U 和 232Th 的浓度随着沉积物中碳含量的增加而降低（R = -0.79 和 -0.81）。所获得的数据表明，在评估海洋沉积物的总天然放射性时，需要考虑 226Ra 的过量，其值可能超过 238U 和 232Th 的放射性。

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来源期刊

Radiochemistry CHEMISTRY, INORGANIC & NUCLEAR-

CiteScore

1.30

自引率

33.30%

发文量

期刊介绍： Radiochemistry is a journal that covers the theoretical and applied aspects of radiochemistry, including basic nuclear physical properties of radionuclides; chemistry of radioactive elements and their compounds; the occurrence and behavior of natural and artificial radionuclides in the environment; nuclear fuel cycle; radiochemical analysis methods and devices; production and isolation of radionuclides, synthesis of labeled compounds, new applications of radioactive tracers; radiochemical aspects of nuclear medicine; radiation chemistry and after-effects of nuclear transformations.

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