Abstract：
Plutonium-239 + 240 and 137Cs in the environment can usually be used to track the impact of nuclear activities on the environment, and have become important tools in environmental geochemical studies. In this study, nine sediment cores (E1-E9) in Lake East Dongting were collected and measured for the activity concentration of 239+240Pu, 137Cs and the atomic ratio of 240Pu/239Pu, and then their vertical distribution characteristics were analyzed. The results show that: the activity concentrations of 137Cs and 239+240Pu in Lake East Dongting ranged from 5.26 ± 0.43 to 28.6 ± 2.23 Bq kg-1 and 0.29 ± 0.02 to 1.37 ± 0.09 Bq kg-1, with an average of 7.48 ± 0.68 Bq kg-1 and 0.39 ± 0.03 Bq kg-1, respectively. The atomic ratios of 240Pu/239Pu are 0.168 ± 0.012-0.211 ± 0.015, which are basically consistent with the global atmospheric deposition. The vertical profiles of 137Cs and 239+240Pu in sediment cores show obvious single-peak distribution in E1-E6 and bimodal distribution in E7-E9. The results of sedimentation rates calculated by 137Cs and 239+240Pu method ranged from 0.59 cm y-1 to 1.99 cm y-1 with a mean of 1.18 cm y-1 and 0.61 cm y-1 to 2.18 cm y-1 with a mean of 1.26 cm y-1. The inventories of 137Cs and 239+240Pu in nine sediment cores are 5.87-10.8 kBq m-2 and 307-545 Bq m-2, which are about 8-14 and 9-15 times the inventory in the global average atmospheric deposition at the same latitude respectively. Comparing the results of the sedimentation rates and the inventories from different sampling points indicates that extreme climatic events and human activities have a significant impact on sediment environment of Lake East Dongting.
摘要：
环境中的钚-239+240和137Cs通常可用于跟踪核活动对环境的影响，并已成为环境地球化学研究的重要工具。在这项研究中,收集并测量了东洞庭湖的9个沉积物岩心（E1-E9）的活度浓度为239240Pu，137Cs和原子比为240Pu/239Pu，然后分析了它们的垂直分布特征。结果表明:东洞庭湖137Cs和239+240Pu的活性浓度范围为5.26±0.43~28.6±2.23Bqkg-1和0.29±0.02~1.37±0.09Bqkg-1,平均浓度分别为7.48±0.68Bqkg-1和0.39±0.03Bq-1。240Pu/239Pu的原子比为0.168±0.012-0.211±0.015，与全球大气沉积基本一致。沉积物岩心中137Cs和239240Pu的垂直剖面在E1-E6中显示出明显的单峰分布，在E7-E9中显示出双峰分布。137Cs和239240Pu方法计算的沉降速率的结果范围为0.59cmy-1至1.99cmy-1，平均值为1.18cmy-1，0.61cmy-1至2.18cmy-1，平均值为1.26cmy-1。9个沉积物岩心的137Cs和239240Pu的库存为5.87-10.8kBqm-2和307-545Bqm-2，分别是全球平均大气沉积库存的8-14和9-15倍。分别在同一纬度。对不同采样点的沉积速率和清单的结果进行比较表明，极端气候事件和人类活动对东洞庭湖的沉积物环境有显著影响。
