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

这一研究项目的最终目标是定性和定量地了解大洋中脊的硫磺循环。迄今在两个主要研究地点(即Logatchev热液田和南部MAR地点)的液体和固体样品中不同形态硫的丰度和同位素结果为包括亚稳态硫醇在内的各种硫化物混合物的无机(地幔硫的淋溶和高温海水硫酸盐还原)和生物(硫酸盐和元素硫的还原)循环提供了证据。目前的估计部分基于初步的多种硫同位素数据，表明循环海水硫酸盐对热液流体总硫收支的贡献为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、淋溶地幔硫、生物硫循环)，以及(Ii)确定大洋中脊热液环境中硫同位素分馏的细节，以及(B)基于所研究的喷口培养生物的培养实验来量化硫代谢和伴生同位素效应。

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.