热液区鳞脚螺铁硫化物矿化元素的富集机理：元素和硫同位素证据

The ‘scaly-foot gastropod’, which carries hundreds of dermal sclerites on its foot and these scales can be covered in iron sulphide that also covers its shell, is thus well-known as an iconic species only found at deep-sea hydrothermal vent in Indian Ocean. Previous studies attributed the formation of iron sulphide in sclerites to the biological controlled biomineration. However, this mechanism is questionable with the facts that ‘scaly-foot gastropod’ have different mineralization capabilities, and there is lack of comparison between the iron sulphide in sclerites and shells. To investigate the mechanisms by which the iron sulfide minerals form in the sclerites and shells, ‘scaly-foot gastropod’ from Kairei and Longqi vent fields as well as individual from laboratory culture will be characterized. It is hoped in this study that we can (1) obtain the sclerites and shells’ mineral, elemental and sulfur isotopic compositions, (2) discuss the mineralized ion transport pathway and understand the biomineralization mechanisms of iron sulfide minerals. The results from this study are expected to provide a novel insight into the biomineralization in earth system as well as the co-evolution of life and hythothermal environment.

鳞脚螺（scaly-foot gastropod）作为印度洋热液区独有的物种，是现知唯一能利用铁硫化物组建身体结构的大生物。前人认为铁硫化物是鳞脚螺体内富集成矿元素后分泌形成的，是生物体适应热液环境的体现。然而，最新调查结果显示鳞脚螺在不同热液场具有不同的矿化表现。因此，鳞脚螺是否主动富集成矿元素存在疑问，其铁硫化物的生物矿化机理需要进一步讨论。本项目通过对印度洋Kairei、龙旂热液场获取的自然鳞脚螺样品和室内培养鳞脚螺样品，（1）运用矿物学和地球化学手段，对鳞片和外壳的铁硫化物进行系统剖析，对比鉴别鳞脚螺不同部位的生物矿化特征；（2）运用微区分析技术，获取铁硫化物的微区矿物、元素、原位硫同位素以及人工标记特征，推演关键矿化元素的迁移和富集途径，进而阐明鳞脚螺生物矿化机理。本研究的开展对于丰富地球系统典型的生物矿化理论体系，进一步理解深海热液系统生命和极端环境的协同演化有着重要意义。

印度洋热液区的鳞脚螺因其体表的铁硫化物矿物而闻名，一直以来是生物矿化作用研究的热门对象之一。在本项目的支持下，我们对西南印度洋Longqi和中印度洋Kairei不同热液区的生物样品进行了采集、培养和分样，完成了不同组织器官的元素和矿物组成特征研究、同位素组成特征研究、以及附着微生物群落组成研究。本项目发现外壳与鳞片上铁硫化物的铁元素和硫元素分布具有明显的不均一性，这说明铁硫化物成矿元素来源途径有着明显的不同；结合16天的生物培养结果，本研究发现硫氧化功能的微生物类群随着培养时间有着明显的变化，这说明生物体与硫元素代谢密切相关，部分硫元素可能通过生物体内部输运，提供了鳞片铁硫化物的矿化物质来源，这会是造成铁硫化物元素分布不均一性的潜在原因。本研究有益于我们进一步对极端环境下的生物地球化学循环的理解。