Vertical distribution and migration of global fallout Pu in forest soils in southwestern China
Vertical distribution and migration of global fallout Pu in forest soils in southwestern China
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DOI：
10.1016/j.jenvrad.2014.06.010
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发表时间：
2014-10-01
影响因子：
2.3
通讯作者：
Uchida, Shigeo
中科院分区：
文献类型：
--
作者：
Bu, Wenting;Zheng, Jian;Uchida, Shigeo
对中国西南地区采集的土壤样品进行了铀同位素分析。钚-240/钚-239的原子比约为0.18，这表明了全球放射性沉降的主要来源。土壤岩心中239+240PU活性达到一致的次表层最大值后呈指数下降。自沉积以来，大部分钚仍停留在0-10 cm层中。采用对流色散方程（CDE）模型估算了土壤中Pu迁移的对流速度和色散系数。有效对流速度和有效色散系数分别为0.05 ~ 0.11 cm/y和0.06 ~ 0.29 cm(2)/y。提出了除降水、土壤粒度分布和有机质外，控制土壤中磷垂直迁移的其他因素。模拟了Pu在土壤中的长期迁移行为。研究结果为今后进一步的环境监测和非全球性降尘性铀输入源识别提供了铀背景基线。(C) 2014 Elsevier Ltd.版权所有。
Soil samples collected in southwestern China were analyzed for Pu isotopes. The Pu-240/Pu-239 atom ratios were around 0.18, which indicated the dominant source of global fallout. Consistent sub-surface maximums followed by exponential decline of 239+240PU activities in the soil cores were observed. Most of the Pu has still remained in the 0-10 cm layers since its deposition. Convection velocities and dispersion coefficients for Pu migration in the soils were estimated by the convection dispersion equation (CDE) model. The effective convection velocities and effective dispersion coefficients ranged from 0.05 to 0.11 cm/y and from 0.06 to 0.29 cm(2)/y, respectively. Other factors that control the vertical migration of Pu in soil besides precipitation, soil particle size distribution and organic matter were suggested. Long-term migration behaviors of Pu in the soils were simulated. The results provide the Pu background baseline for further environmental monitoring and source identification of non-global fallout Pu inputs in the future. (C) 2014 Elsevier Ltd. All rights reserved.