Determination and Assessment of Transuranic Isotopes (Pu, Np, Am) Activities and Isotopes Ratios in Antarctic Marine Sediments
Determination and Assessment of Transuranic Isotopes (Pu, Np, Am) Activities and Isotopes Ratios in Antarctic Marine Sediments
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DOI：
10.1021/acsearthspacechem.1c00314
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发表时间：
2021-11
影响因子：
3.4
通讯作者：
Xibin Han;Xiaoxiao Han;Zhihong Li;Zhiyong Liu;Yongcong Zhang;Liangming Hu
中科院分区：
文献类型：
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作者：
Xibin Han;Xiaoxiao Han;Zhihong Li;Zhiyong Liu;Yongcong Zhang;Liangming Hu
由于20世纪的核试验，大量人为的超铀同位素（237Np、239、240Pu和241am）产生、扩散和沉积在包括南极洲在内的自然环境中。利用ICP-SF-MS测定了239+240Pu、237Np和241am在南极海洋沉积物中的活度，239+240Pu的活度范围为0.008 ~ 0.293 Bq/kg，237Np的活度范围为0.057 ~ 0.926 mBq/kg， 241am的活度范围为0.027 ~ 0.277 Bq/kg。研究区海洋沉积物中237np、239、240Pu和241am的主要来源是全球沉降。240Pu/239Pu原子比平均为0.179±0.010 (n= 17)，与核武器试验的全球沉降一致。建议全球沉降物的平均237np /239Pu原子比为0.221 (n= 58)，可作为指示某一地区当前Np源的新特征指标。由于海水对Pu和Am的不同分馏度以及海洋颗粒的富集效率，这些样品中的241Am/239+240Pu活度比（平均值2.037±0.040,n= 17）远高于全球沉降物。此外，发现237Np/239Pu原子比和241am /239+240Pu活性比与采样深度呈正相关。此外，还揭示了有机质与8种重金属与超铀活性的相关性。寒冷的气候、纬度和沉积物性质对南极海相沉积物中Np、Pu和Am的分布有重要影响。
Due to the nuclear testing in the 20th century, a considerable amount of anthropogenic transuranic isotopes (237Np,239, 240Pu, and241Am) was produced, spread, and deposited in the natural environment including Antarctica. Here, activities of239+240Pu,237Np, and241Am in Antarctic marine sediments are determined by ICP-SF-MS, ranging from 0.008 to 0.293 Bq/kg for239+240Pu, from 0.057 to 0.926 mBq/kg for237Np, and from 0.027 to 0.277 Bq/kg for241Am. The dominant source of237Np,239, 240Pu, and241Am in the study marine sediments is global fallout.240Pu/239Pu atom ratio is measured to be 0.179 ± 0.010 (n= 17) on average, which is consistent with the global fallout of the nuclear weapons tests. Average237Np/239Pu atom ratio for global fallout is suggested as 0.221 (n= 58), which may be used as a new characteristic index to indicate the current source of Np in a certain region. Due to the different fractionations of Pu and Am by seawater and the enrichment efficiency of marine particles,241Am/239+240Pu activity ratios in these samples (mean, 2.037 ± 0.040;n= 17) are much higher than global fallout. In addition,237Np/239Pu atom ratio and241Am/239+240Pu activity ratio are found to be positively correlated with the sampling depth. Furthermore, the correlation between organic matter and eight heavy metals with transuranic activities is revealed. The cold climate, latitude, and sediment properties have an important influence on the distributions of Np, Pu, and Am in these marine sediments of Antarctic.