| 210Po-210Pb活度不平衡鉴年法测定北极冰区表层冰雪年龄 |
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| 引用本文： | 钟强强,王求贵,于涛,黄德坤,王浩,陈随缘.210Po-210Pb活度不平衡鉴年法测定北极冰区表层冰雪年龄[J].海洋学报,2022,44(9):63-72. |
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| 作者姓名： | 钟强强 王求贵 于涛 黄德坤 王浩 陈随缘 |
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| 作者单位： | 1.自然资源部第三海洋研究所 海洋生态环境预警监测研究室，福建 厦门 361005 |
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| 基金项目： | 中国博士后科学基金（2021M693780）；南海海洋资源利用国家重点实验室（海南大学）开放课题(MRUKF2021015)；福建省社会发展引导性（重点）项目（2019Y0073）；自然资源部第三海洋研究所基本科研业务费专项（海三科2018029）。 |
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| 摘 要： | 远离河流和大陆的北冰洋冰区，大气沉降是210Po、210Bi、210Pb和7Be核素等最重要的来源。降雪一旦形成即被标记具有特定的210Po/210Pb活度比值，并降落到海冰表面，进入封闭状态。在封闭体系的冰雪中，随着时间推移，210Po从相对于210Pb强烈亏损的状态逐渐达到210Po-210Pb平衡状态。因此可以通过分析北冰洋表层冰雪中210Po-210Pb活度不平衡特征，量化冰区表层冰雪的表观年龄。本文搜集整理了北极地区气溶胶的210Po/210Pb活度比值，结合2018年中国第9次北极科学考察航次和2015年美国GEOTRACES 北冰洋航次中若干冰站表层冰雪的210Po/210Pb活度比特征，估算了北冰洋表层冰雪的表观年龄。结果表明，2018年中国冰站采集的表层冰雪年龄变化范围为106～272 d，远大于2015年美国冰站采集的表层冰雪的年龄；而两国冰站表层冰雪的年龄都呈现一定的纬度效应，即随着采样站位越靠近北极点，总体上表层冰雪的年龄呈现越来越大的特点，表明北极冰区表层冰雪越靠近北极点，表层冰雪被保留的时间会越长。210Po-210Pb 活度不平衡定年法可以作为一种评估北冰洋冰雪年龄的方法并与遥感技术协同使用。
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| 关 键 词： | 210Po-210Pb活度不平衡 定年 冰雪年龄 北冰洋 |
| 收稿时间： | 2021-10-13 |
Dating the age of surficial snow in the Arctic Ocean by 210Po-210Pb activity disequilibria |
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| Institution: | 1.Laboratory of Marine Ecological Environment Early Warning and Monitoring, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China2.School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China3.Key Laboratory of Global Change and Marine-Atmospheric Chemistry, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China |
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| Abstract: | Atmospheric deposition is the most important source for 210Po, 210Bi, 210Pb and 7Be radionuclides in the Arctic sea ice regions far away from the influence of rivers and continents. Once the precipitation or snow forms in the Arctic, the falling snow underneath the cloud would be tagged with the specific 210Po/210Pb activity ratio and be locked into a closed environment; as time elapses, this ratio in snow increases to equilibrium state of 210Po-210Pb due to 210Po ingrowth from the decay of 210Pb. From the measured 210Po/210Pb activity disequilibria in the surficial snow of the Arctic Ocean, its age can be constrained. Here, this research compiled the 210Po/210Pb activity ratio of aerosol in the Arctic region as the initial ratio for dating snow. The apparent ages of surficial snow in the Arctic Ocean were estimated based on the measured 210Po/210Pb activity ratio in the surficial snow from the ice stations during the Chinese Ninth Arctic cruise in 2018 and the US GEOTRACES Arctic cruise in 2015. The results showed that the age of snow collected by Chinese ice stations in 2018 ranged from 106 d to 272 d, which was much older than that of snow collected by US ice stations in 2015. The ages of surficial snow showed an obvious latitude effect for both two cruises, indicating that the closer the surficial snow in the Arctic was to the North Pole, the older the snow was. 210Po-210Pb activity disequilibrium can be used as an effective dating tool combined with passive microwave satellite remote sensing technology to constrain the age of ice/snow in the polar region. |
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