摘要
稳定锶同位素(δ88/86Sr)是近年来新兴的一种非传统稳定同位素,应用其示踪大陆风化过程与海洋锶循环已成为学术界一个研究热点。目前稳定锶同位素质谱测试精度可优于0.03‰,自然界不同地质体δ88/86Sr的变化范围为-3.65‰~1.68‰。研究发现,流域风化过程中原生矿物的差异性溶解、次生矿物的形成与吸附作用、碳酸钙沉淀以及生物作用都会使得流体相δ88/86Sr升高,而固体相δ88/86Sr降低,从而导致稳定锶同位素在河流溶解态和颗粒态具有不同的地球化学行为。河流沉积物δ88/86Sr随着风化强度的增强而降低,具有示踪流域化学风化强度的潜力。同时,当前亟需深入研究表生风化过程中稳定锶同位素的分馏机制及制约因素,这是运用河水δ88/86Sr示踪流域化学风化的关键,也为深入理解全球海洋锶循环提供借鉴。
The new non-traditional stable strontium(Sr)isotope has aroused great attention from academic scholars in terms of the continental weathering and marine Sr cycle.The analytical precision of stable Sr isotope using mass spectrometry is better than 0.03‰.The compiledδ88/86Sr values vary from-3.65‰to 1.68‰in natural reservoirs.Recent findings indicate that multiple processes can cause stable Sr isotope fractionation in Earth surface,including the incongruent dissolution of primary minerals,the formation and adsorption of secondary minerals,the precipitation of calcium carbonate,and the biological cycling.These processes lead to higherδ88/86Sr in the liquid phase and lowerδ88/86Sr in the solid phase,and thus result in different geochemical behavior of stable Sr isotopes in water and sediment during the weathering processes.Theδ88/86Sr values of river sediment decrease with the increase of weathering intensity,which has the potential to indicate chemical weathering intensity.Meanwhile,further study on the fractionation mechanisms and constraints of stable Sr isotopes in river water plays an important role in tracing chemical weathering processes within the watershed,which will lead to a better understanding of the global ocean Sr cycle.
作者
赖正
苏妮
吴舟扬
连尔刚
杨承帆
李芳亮
杨守业
Lai Zheng;Su Ni;Wu Zhouyang;Lian Ergang;Yang Chengfan;Li Fangliang;Yang Shouye(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China)
出处
《地球科学进展》
CAS
CSCD
北大核心
2020年第7期691-703,共13页
Advances in Earth Science
基金
青岛海洋科学与技术国家实验室开放基金项目“多同位素示踪极端事件对东海沉积物源汇关键过程的影响”(编号:QNLM2016ORO0211)
国家自然科学基金项目“山溪性入海河流物源变异及对气候事件的响应”(编号:41776062)资助
关键词
稳定锶同位素
流域风化
分馏机制
地球化学示踪
δ88/86Sr
Chemical weathering
Fractionation mechanism
Geochemical tracing
