What is the major control on barium isotopes within the sediment and pore-water fraction in surface sediments?

钡(巴)同位素是一种新型示踪剂，有可能提供有关过去海洋生物生产力的信息(Bridsterock等人，2018年；Bridsterock等人，2019年)。与海洋重晶石堆积相比，钡同位素的一个主要好处是它们应该对保存和稀释效应不敏感(Carter等人，2020年)。这一应用的基础是假设海洋沉积物中的BA从上层水柱继承其同位素特征(Bridsterock等人，2018年)。然而，这一假设的保真度目前缺乏约束，需要通过获得跨越生物生产力和早期成岩条件下的梯度的现代沉积物的Ba同位素数据进行验证。IODP EXP 391提供了一个收集岩心顶部沉积物和孔隙水的独特机会，非常适合于解决这一知识差距。为此，拟议的研究旨在测量IODP Exp 391巡航所有地点的海水、岩芯顶部沉积物和孔隙水中的[Ba]和Ba同位素值。这些数据将被用来测试顶层沉积物的完整性，这些沉积物从上覆水域继承了其同位素特征，跨越了一系列浅层沉积物氧化还原环境和海洋生物生产力的大梯度。这项研究将填补在现代海洋环境中沉积Ba2+积累和Ba2+同位素的关键知识空白，从而有助于提高海洋重晶石作为古生产力指标的利用。

Barium (Ba) isotopes are a novel tracer with the potential to provide information on past marine biological productivity (Bridgestock et al., 2018; Bridgestock et al., 2019). A major benefit of barium isotopes over marine barite accumulation is that they should be insensitive to preservation and dilution effects (Carter et al., 2020). The basis of this application is that Ba in marine sediment is assumed to inherit its isotopic signature from the upper water column (Bridgestock et al., 2018). However, the fidelity of this assumption is currently poorly constrained, and requires validation through obtaining Ba isotope data for modern sediments spanning gradients in biological productivity and early diagenetic conditions. IODP EXP 391 provides a unique opportunity to collect core-top sediments and pore-waters ideally suited to addressing this knowledge gap. To this end, the proposed research aims to measure [Ba] and Ba isotope values from seawater, core-top sediments and pore-waters from all sites of the IODP EXP 391 cruise. This data will be used to test the integrity of top sediments inheriting their isotopic signature from the overlying waters across a range of shallow sediment redox environments and a large gradient in marine biological productivity. This study will fill key knowledge gaps on sedimentary barium accumulation and barium isotopes in modern marine setting thus helping improve the use of marine barite as a palaeo-productivity proxy.