摘要
放射性核素示踪技术被广泛应用于海洋学研究。海洋沉积物是许多物质的归宿,海洋沉积过程的研究常关注3个关联问题:物质来源、沉积速率、再悬浮过程。针对这3个问题,在南海9个珊瑚礁区、北部湾涠洲岛海域、珠江口、北冰洋、南大洋等多个海区利用典型的铀系放射性核素(210Pb、226Ra、234Th、238U)示踪技术开展海洋沉积过程研究。物源识别方面,研究发现珊瑚礁区沉积物具有极低的226Ra/238U活度比值(<0.1),显著低于其他海区的226Ra/238U活度比值(0.5~1.0),该独特性质可以应用于珊瑚礁区的沉积物/悬浮物来源示踪,是其他传统元素地球化学方法(Al、Ti、稀土元素)的补充。沉积速率方面,基于210Pb的恒定通量恒定沉积速率(Constant Flux Constant Sedimentation Model,CFCS)模式,定量计算了广西涠洲岛珊瑚礁区沉积柱样的沉积速率(3.7±0.6 mm/a),该结果低于中国多个近岸海域的沉积速率(5~96 mm/a)。沉积物再悬浮方面,提出利用“残余234Th”(不同于过剩234Th)示踪海洋沉积物再悬浮过程,并成功应用于北冰洋、南海、南大洋。
Radionuclides are widely used as tracers in oceanography.As the final fate of many substances,marine sediment is mainly concerned from three perspectives:source identification,sedimentation rate,and sediment resuspension.In the present study,uranium-series radionuclides(210Pb,226Ra,234Th,and 238U)are applied in several sea regions such as the nine typical coral reefs in the South China Sea,the Weizhou Island,the Pearl River Estuary,the Arctic Ocean,and the Southern Ocean,to study the sediment source,sedimentation rate,and sediment resuspension.Firstly,activity ratio of 226Ra to 238U was found extremely low(<0.1)in the marine sediment of coral reef regions comparing to the activity ratios(0.5~1.0)in other marine sediments and therefore,it could be used as the tool to identify the sources of marine sediments from coral reef regions in addition to other geochemical tools(Al,Ti,and REE).Secondly,the sedimentation rate(3.7±0.6 mm/a)was calculated for a sediment core taking from the coral reefs near the Weizhou Island via excess 210Pb(Constant Flux Constant Sedimentation Model,CFCS model in brief)which was lower than most figures(5 mm/a^96 mm/a)in other coastal areas of China.Finally,residualβactivity of particulate 234Th(RAP234)was proposed for tracking marine sediment resuspension.The RAP234 was successfully applied in the Arctic Ocean,South China Sea,and Southern Ocean.In conclusion,the successful applications of these radioactive tracers have provided potential tools used for tracing marine sedimentary processes in addition to the ongoing toolbox.
作者
林武辉
余克服
王英辉
刘昕明
陈立奇
LIN Wuhui;YU Kefu;WANG Yinghui;LIU Xinming;CHEN Liqi(Guangxi Laboratory on the study of Coral Reefs in the South China Sea,Nanning 530004,China;School of Marine Sciences,Guangxi University,Nanning 530004,China;Guangxi Academy of Oceanography,Nanning 530022,China;Key Lab of Global Change and Marine-Atmospheric Chemistry,Ministry of Natural Resources,Xiamen 361005,China)
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2020年第1期60-70,共11页
Marine Geology & Quaternary Geology
基金
国家重大科学研究计划项目“南海珊瑚礁对多尺度热带海洋环境变化的响应、记录与适应对策研究”（2013CB956102）
国家自然科学基金“珊瑚礁千米深钻记录的西沙碳酸盐台地形成演化和环境变迁史”（91428203），“南海造礁珊瑚对海洋人工放射性核素90Sr源汇过程的指示作用研究”（41906043）
广西“珊瑚礁资源与环境”八桂学者（2014BGXZGX03）
广西自然科学基金面上项目“北部湾海洋沉积物中放射性核素的分布格局和调控机制研究”（2019GXNSFAA185006）
国家海洋局海洋-大气化学与全球变化重点实验室开放基金“造礁珊瑚对海水中人工放射性核素90Sr的指示作用研究”（GCMAC1606）
关键词
放射性核素
沉积物
示踪
珊瑚礁
残余234Th
radionuclides
sediment
tracer
coral reefs
residualβactivity of particulate 234Th
