The Impact of Microbes for Seafloor Massive Sulfide Formation, Transformation and Dissolution

海底块状硫化物(SMS)矿床是在现代海底活动的高温热液喷口系统中，通过富含矿物的平流热液流体与海底海水混合而形成的。它们主要由黄铁矿和黄铜矿组成，并含有铜等贵金属。当含氧海水穿透SMS时，硫化物矿物暴露在非生物氧化风化中。微生物活动通过催化硫化物矿物的沉淀、金属的迁移和矿物的溶解，大大加速了这一过程。在某些情况下，可以形成富铁硅盖层，从而导致盖层以下的低氧浓度，从而保护硫化物矿床免受直接氧化、非生物和生物风化，并延长这些矿床的寿命。在这里，我们将研究微生物活性在有氧和低氧条件下对矿物形成、转化和溶解的影响。我们将把分子生物学技术与培养实验、微生物培养工作和生理研究相结合。我们将确定哪些微生物主要负责矿物转化和金属活化，并确定周转率和矿物修饰，以预测不同氧气条件下微生物活动如何影响Sms矿床的寿命。

Seafloor massive sulfide (SMS) deposits form on the modern ocean floor at active high-temperature hydrothermal vent systems through mixing of mineral-rich, advecting hydrothermal fluids with bottom seawater. They are mainly composed of pyrite and chalcopyrite and contain valuable metals such as copper. When oxygenated seawater penetrates the SMS, the sulfide minerals are exposed to abiotic oxidative weathering. Microbial activity considerably accelerates this process by catalyzing the precipitation of sulfide minerals, metal transport and mineral dissolution. Under certain circumstances iron-rich-silica-caps can be formed, which result in low oxygen concentrations below the caprock, thus sheltering the sulfide deposits from direct oxidative abiotic and biotic weathering and prolonging the lifetime of these deposits. Here we will examine the impact of microbial activity for SMS formation, transformation and dissolution of minerals under oxic and low oxygen conditions. We will combine molecular biological techniques with incubation experiments, microbial enrichment work and physiological studies. We will determine, which microbes are primarily responsible for the mineral transformation and metal mobilization and determine turnover rates and mineral modifications to predict, using adapted geochemical models, how microbial activity affects the lifetime of SMS deposits under different oxygen conditions.