| 渤海沉积物中放射性核素分布及其对沉积环境变化的响应 |
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| 引用本文： | 杜金秋,王震,林武辉,路波,高会,王宇宁,姚子伟,关道明.渤海沉积物中放射性核素分布及其对沉积环境变化的响应[J].地球科学,2021,46(12):4503-4516. |
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| 作者姓名： | 杜金秋 王震 林武辉 路波 高会 王宇宁 姚子伟 关道明 |
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| 作者单位： | 1.国家海洋环境监测中心, 辽宁大连 116023 |
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| 基金项目： | 国家自然科学基金41807383河口海岸学国家重点实验室开放基金SKLEC-KF201712国家海洋局海洋沉积与环境地质重点实验室开放基金MASEG201709 |
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| 摘 要： | 为了探讨近百年来，人类活动背景下近海沉积物中放射性核素的沉积记录及其对物质输入与埋藏等沉积环境变化的响应，利用γ能谱法对渤海表层和柱状沉积物中的放射性核素238U、226Ra、232Th、210Pb、40K和137Cs进行分析.结果显示，渤海沉积物中放射性核素水平和垂直分布特征明显，铀衰变系核素238U、226Ra和210Pb不平衡，232Th和210Pb受沉积物粒度和有机碳影响显著，238U与226Ra、232Th、40K存在显著相关性.226Ra/238U、232Th/238U和40K/238U比值时空差异显著，渤海沉积物陆源输入影响由西南向东北方向延伸，受河流影响，渤海北部和南部的沉积物输入不稳定，近几十年波动显著.利用210Pbex和137Cs法的测年结果计算获得的渤海近百年来沉积速率在中国近海沉积速率研究背景值范围内；空间上，渤海北部、中部和南部沉积速率处于同一水平，其中北部偏高；时间上，近百年来渤海沉积速率随时间波动，整体上呈现增加趋势，尤其是1980年之后，人类活动影响下渤海沉积速率增加幅度显著，与沉积物输入的波动变化相对应.
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| 关 键 词： | 放射性核素 沉积速率 渤海 沉积环境 演变 地球化学 |
| 收稿时间： | 2021-04-27 |
Distribution of Radionuclides in Sediments of Bohai Sea and Their Response to Changes in Sedimentary Environment |
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| Abstract: | In order to investigate the temporal and spatial changes of the offshore sedimentary processes such as terrestrial material input and sedimentation rate in the context of human activities during the past 100 years, the radionuclides 238U, 226Ra, 232Th, 210Pb, 40K and 137Cs in surface and column sediments in the Bohai Sea region were analyzed using γ energy spectrometry. The horizontal and vertical distribution characteristics of radionuclides in the sediments of the Bohai Sea were obvious, and the radionuclides 238U, 226Ra and 210Pb in the uranium decay series were unbalanced. 232Th and 210Pb were significantly affected by sediment grain size and organic carbon. The correlation between 238U and 226Ra, 232Th, 40K was obvious. There were significant temporal and spatial differences in the ratios of 226Ra/238U, 232Th/238U and 40K/238U. The influence of terrestrial input of Bohai Sea sediments extends from southwest to northeast. Affected by rivers, the sediments in the northern and southern Bohai Sea material input were unstable and fluctuated significantly in recent decades. The sedimentation rate calculated by the 210Pbex and 137Cs dating methods in the Bohai Sea in the past 100 years was within the background value of the sedimentation rate research in the offshore China. Spatially, the sedimentation rate was at the same level in the northern part, central part and southern part, among which it was relatively high in the northern part. Temporally speaking, the sedimentation rate of the Bohai Sea fluctuated with time in the past 100 years and showed an overall increasing trend, especially since 1980, under the influence of human activities, the increase was significant, corresponding to the changes in sediment input. |
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