Ba/Ca of stylasterid coral skeletons records dissolved seawater barium concentrations
Ba/Ca of stylasterid coral skeletons records dissolved seawater barium concentrations
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DOI：
10.1016/j.chemgeo.2023.121355
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发表时间：
2023-02-24
期刊：
影响因子：
3.9
通讯作者：
Haussermann，Vreni
中科院分区：
文献类型：
--
作者：
Kershaw，James;Stewart，Joseph A.;Haussermann，Vreni
海水中溶解的Ba2+浓度受初级生产力和海洋环流模式的影响。因此，重建过去的地下[Ba]SWs可以提供有关调节全球气候的过程的重要信息。前人对深海珊瑚骨骼和竹子深海珊瑚骨骼的Ba/Ca测量与[Ba]Sw呈线性关系，为过去的Ba循环提供了档案。然而，海鞘藻科是一组分布广泛的固氮黄藻类水生动物珊瑚，其骨骼的BA/Ca比值以前从未被研究过。在这里，我们给出了现代螺类珊瑚(文石、钙质和混合矿物学)和固氮黄藻类硬壳珊瑚骨骼的BA/Ca比值，并结合已发表的近端水文数据。我们发现，[BA]SWs和样品矿物学是Stlasterid Ba/Ca的主控因素，而海水温度的次要控制作用较弱。[BA]SWs对固氮菌BA/Ca也有较强的抑制作用。然而，不同的地点和不同的深度梯度，板岩骨架中的Ba含量不同，我们发现板岩骨架中的Ba/Ca与[BA]SW值之间的关系比以前报道的更为敏感。我们发现，这些过程对茎类珊瑚骨骼中掺入Ba的影响较小，这一结果与其骨骼地球化学的其他方面一致。因此，Stylasterid的Ba/Ca比值是过去[Ba]Sw变化的有力、新颖的档案，特别是当与Li/Mg或Sr/Ca等温度敏感示踪剂一起测量时。事实上，随着[Ba]SWs和温度替代物的建立，类固醇类化合物有可能成为古海洋学研究的重要新档案。
The concentration of dissolved barium in seawater ([Ba]SW) is influenced by both primary productivity and ocean circulation patterns. Reconstructing past subsurface [Ba]SWcan therefore provide important information on processes which regulate global climate. Previous Ba/Ca measurements of scleractinian and bamboo deep-sea coral skeletons exhibit linear relationships with [Ba]SW, acting as archives for past Ba cycling. However, skeletal Ba/Ca ratios of the Stylasteridae – a group of widely distributed, azooxanthellate, hydrozoan coral – have not been previously studied.Here, we present Ba/Ca ratios of modern stylasterid (aragonitic, calcitic and mixed mineralogy) and azooxanthellate scleractinian skeletons, paired with published proximal hydrographic data. We find that [Ba]SWand sample mineralogy are the primary controls on stylasterid Ba/Ca, while seawater temperature exerts a weak secondary control. [Ba]SWalso exerts a strong control on azooxanthellate scleractinian Ba/Ca. However, Ba-incorporation into scleractinian skeletons varies between locations and across depth gradients, and we find a more sensitive relationship between scleractinian Ba/Ca and [Ba]SWthan previously reported.Paired Sr/Ca measurements suggest that this variability in scleractinian Ba/Ca may result from the influence of varying degrees of Rayleigh fractionation during calcification. We find that these processes exert a smaller influence on Ba-incorporation into stylasterid coral skeletons, a result consistent with other aspects of their skeletal geochemistry. Stylasterid Ba/Ca ratios are therefore a powerful, novel archive of past changes in [Ba]SW, particularly when measured in combination with temperature sensitive tracers such as Li/Mg or Sr/Ca. Indeed, with robust [Ba]SWand temperature proxies now established, stylasterids have the potential to be an important new archive for palaeoceanographic studies.