Barium isotopes in cold-water corals
Barium isotopes in cold-water corals
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DOI：
10.1016/j.epsl.2018.03.040
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发表时间：
2018-06-01
影响因子：
5.3
通讯作者：
Henderson, Gideon M.
中科院分区：
文献类型：
--
作者：
Hemsing, Freya;Hsieh, Yu-Te;Henderson, Gideon M.
最近的研究引入了稳定的Ba同位素（δ（138）/Ba-134）作为海洋过程的新示踪剂。钡同位素可能提供深入了解海洋钡循环，海洋的生物泵，在深海中的水团来源，热液喷口的活动变化，陆-海相互作用，包括跟踪河流输入。在这里，我们表明，文石骨骼的各种殖民地和孤立的冷水珊瑚（CWC）类群记录海水（SW）钡同位素组成。分析了来自三个海洋区域的8个不同分类群的36种珊瑚，并将其与对同一地点海水样本的Delta（138）/Ba-134测量值进行了比较。地点的选择，以涵盖广泛的温度，盐度，钡浓度和钡同位素组成。在三个站点的海水样品表现出良好的Ba浓度和δ（138）/Ba-134之间的反相关性。此外，我们的数据集表明，Ba/Ca值在CWC与周围海水中溶解[Ba]呈线性相关，与D-CWC/SW = 1.8 +/- 0.4（2SD）的平均分配系数。海水和CWCs Delta（138）/Ba-134（CWC-SW）之间Ba的平均同位素分馏为-0.21 +/-0.08 ‰（2SD），表明CWC文石优先结合较轻的同位素。这种分馏可能不依赖于温度或其他环境变量，这表明文石CWC可用于跟踪环境海水中的Ba同位素组成。对化石CWCs的[Ba]和Delta（138）/Ba-134的耦合分析有可能提供关于[Ba]和Delta（138）/Ba-134之间的局部和全球关系的过去变化的新信息，从而提供关于过去全球海洋Ba循环在不同气候体制中的运作的新信息。(C)2018爱思唯尔B. V.保留所有权利。
Recent studies have introduced stable Ba isotopes (delta(138)/Ba-134) as a novel tracer for ocean processes. Ba isotopes could potentially provide insight into the oceanic Ba cycle, the ocean's biological pump, water-mass provenance in the deep ocean, changes in activity of hydrothermal vents, and land-sea interactions including tracing riverine inputs. Here, we show that aragonite skeletons of various colonial and solitary cold-water coral (CWC) taxa record the seawater (SW) Ba isotope composition. Thirty-six corals of eight different taxa from three oceanic regions were analysed and compared to delta(138)/Ba-134 measurements of co-located seawater samples. Sites were chosen to cover a wide range of temperature, salinity, Ba concentrations and Ba isotope compositions. Seawater samples at the three sites exhibit the well-established anti-correlation between Ba concentration and delta(138)/Ba-134. Furthermore, our data set suggests that Ba/Ca values in CWCs are linearly correlated with dissolved [Ba] in ambient seawater, with an average partition coefficient of D-CWC/SW = 1.8 +/- 0.4 (2SD). The mean isotope fractionation of Ba between seawater and CWCs Delta(138)/Ba-134(CWC-SW) is -0.21 +/- 0.08 parts per thousand (2SD), indicating that CWC aragonite preferentially incorporates the lighter isotopes. This fractionation likely does not depend on temperature or other environmental variables, suggesting that aragonite CWCs could be used to trace the Ba isotope composition in ambient seawater. Coupled [Ba] and delta(138)/Ba-134 analysis on fossil CWCs has the potential to provide new information about past changes in the local and global relationship between [Ba] and delta(138)/Ba-134 and hence about the operation of the past global oceanic Ba cycle in different climate regimes. (C) 2018 Elsevier B.V. All rights reserved.