Controls on Lithium Incorporation and Isotopic Fractionation in Large Benthic Foraminifera
Controls on Lithium Incorporation and Isotopic Fractionation in Large Benthic Foraminifera
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DOI：
10.3390/min13010127
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发表时间：
2023-01-01
期刊：
影响因子：
2.5
通讯作者：
Bijma, Jelle
中科院分区：
文献类型：
--
作者：
Charrieau, Laurie M.;Rollion-Bard, Claire;Bijma, Jelle
碳酸盐岩的锂同位素组成被认为是过去海水锂同位素组成的可靠档案，可用作硅酸盐风化的示踪剂。然而，在两项使用Amphistegina属大型底栖有孔虫的类似物种进行的研究中，Li-7值的变化取决于pH值或DIC。为了解决这个问题，我们进行了培养实验，在解耦的pH-DIC条件下，在两种不同的光处理，并与正常或富锂的海水。用离子探针和LA-ICP-MS分析了有孔虫实验中δ Li-7值和Li/Ca比值。没有任何联系之间的pH值或DIC和Δ Li-7或Li/Ca值观察到的任何治疗，和增长率似乎也没有影响锂的掺入或同位素分馏，从无机碳酸盐沉淀实验的观察结果相反。总体而言，这些发现似乎支持使用大型底栖有孔虫中的锂同位素来重建过去的海水化学并推断碳循环扰动期间化学风化的变化。
The lithium (Li) isotopic composition of carbonates is considered to be a reliable archive of past seawater Li isotopic compositions, which are useful as a tracer of silicate weathering. However, delta Li-7 values have been shown to be dependent on either pH or DIC in two studies using similar species of large, benthic foraminifera from the genus Amphistegina. To resolve this issue, we conducted culture experiments on Amphistegina lessonii in decoupled pH-DIC conditions, under two different light treatments, and with normal or Li-enriched seawater. The delta Li-7 values and Li/Ca ratios in the foraminifera tests were analysed by ion microprobe and LA-ICP-MS, respectively. No links between either the pH or DIC and delta Li-7 or Li/Ca values were observed for any of the treatments, and growth rates also did not seem to influence the Li incorporation or isotopic fractionation, contrary to observations from inorganic carbonate-precipitation experiments. Overall, these findings appear to support the use of Li isotopes in large benthic foraminifera to reconstruct past seawater chemistry and to infer changes in chemical weathering during carbon-cycle perturbations.