Distribution of Cs-137 and Co-60 in plough layer of farmland: Evidenced from a lysimeter experiment using undisturbed soil columns

文献类型： 外文期刊

第一作者： Liu, Wenxiang

作者： Liu, Wenxiang;Li, Yong;Yu, Hanging;Gong, Daozhi;Li, Yong;Saggar, Surinder;Zhang, Qiong

作者机构：

关键词： aeolian sandy soil; brown soil; deposited radionuclide; migration depth; radionuclide; vertical migration rate

期刊名称：PEDOSPHERE （ 影响因子：3.911； 五年影响因子：4.814 ）

ISSN： 1002-0160

年卷期： 2021 年 31 卷 1 期

页码：

收录情况： SCI

摘要： Radionuclide fallout during nuclear accidents on the land may impair the atmosphere, contaminate farmland soils and crops, and can even reach the groundwater. Previous research focused on the field distribution of deposited radionuclides in farmland soils, but details of the amounts of radionuclides in the plough layer and the changes in their proportional distribution in the soil profile with time are still inadequate. In this study, a lysimeter experiment was conducted to determine the vertical migration of Cs-137 and( 60)Co in brown and aeolian sandy soils, collected from the farmlands adjoining Shidaowan Nuclear Power Plant (NPP) in eastern China, and to identify the factors influencing their migration depths in soil. At the end of the experiment (800 d), > 96% of added Cs-137 and( 60)Co were retained in the top 0-20 cm soil layer of both soils; very little Cs-137 or Co-60 initially migrated to 20-30 cm, but their amounts at this depth increased with time. The migration depth of Cs-137 was greater in the aeolian sandy soil than in the brown soil during 0-577 d, but at the end of the experiment, Cs-137 migrated to the same depth (25 cm) in both soils. Three phases on the vertical migration rate (v) of Co-60 in the aeolian sandy soil can be identified: an initial rapid movement (0-355 d, v = 219 +/- 17 mm year followed by a steady movement (355-577 d, v = 150 +/- 24 mm year(-1)) and a very slow movement (577-800 d, v = 107 +/- 7 mm year(-1)). In contrast, its migration rate in the brown soil (v = 133 +/- 17 mm year(-1)) was steady throughout the 800-d experimental period. The migration of both Cs-137 and Co-60 in the two soils appears to be regulated by soil clay and silt fractions that provide most of the soil surface area, soil organic carbon (SOC), and soil pH, which were manifested by the solid-liquid distribution coefficient of Cs-137 and Co-60. The results of this study suggest that most Cs-137 and( 60)Co remained within the top layer (0-20 cm depth) of farmland soils following a simulated NPP accident, and little reached the subsurface (20-30 cm depth). Fixation of radionuclides onto clay minerals may limit their migration in soil, but some could be laterally distributed by soil erosion and taken up by crops, and migrate into groundwater in a high water table level area after several decades. Remediation measures, therefore, should focus on reducing their impact on the farmland soils, crops, and water.

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