Sulphur isotopic investigation of dissolved and solid sulphur phases in fluids, mineral precipitates, sediments and rock samples from the Mid-Atlantic Ridge

本研究项目的最终目的是对大洋中脊的硫循环进行定性和定量的了解。迄今为止，从两个主要研究地点（即logatchev热液场和南部MAR地点）获得的液体和固体样品中不同形式硫的丰度和同位素结果为包括亚稳硫醇在内的多种硫化物混合物的无机（地幔硫的浸出和高温海水硫酸盐还原）和生物（硫酸盐和单质硫的还原）循环提供了证据。目前的估计，部分基于初步的多重硫同位素数据，指出循环海水硫酸盐对热液流体总体硫收支的贡献为30%。未来的工作将集中在两个不同的方面：(a)在不同空间分辨率下测定多种硫同位素，以便(i)量化不同的硫贡献（即循环海水硫酸盐、浸出地幔硫、生物硫循环）；（ii）确定大洋中脊-热液环境下硫同位素分馏的细节；(b)基于从研究的喷口处培养的生物进行培养实验，量化硫代谢和相关的同位素效应。

The ultimate objective of this research project is a qualitative and quantitative understandingof sulphur cycling at mid-ocean ridges. Abundance and isotope results obtained so far fordifferent sulphur forms in liquid and solid samples from the two principal study sites (i.e.Logatchev hydrothermal field and southern MAR sites) provide evidence for inorganic(leaching of mantle sulphur and high-temperature seawater sulphate reduction) andbiological (reduction of sulphate and elemental sulphur) cycling of a diverse mix of sulphurcompounds, including metastable thiols. Current estimates, in part based on preliminarymultiple sulphur isotope data, point to a 30% contribution from recycled seawater sulphate tothe overall sulphur budget of hydrothermal fluids.Future work will focus on two different aspects: (a) the determination of multiple sulphurisotopes at different spatial resolutions in order to (i) quantify the different sulphurcontributions (i.e. recycled seawater sulphate, leached mantle sulphur, biological sulphurcycling, and (ii) identify the details of sulphur isotope fractionation at mid-ocean ridgehydrothermal settings, and (b) the quantification of sulphur metabolism and associatedisotope effects based on culture experiments with organisms cultivated from the vent sitesstudied.