Collaborative Research: Biogeochemical Controls on Antimony and Arsenic Mobility in a Siliceous Hydrothermal Systems

电话：0545336/0544960班尼特S. ENGELEl Tatio是已知最大的间歇泉区之一，有100多个地图热液特征，是智利第二区的文化宝藏和区域旅游资源。间歇泉水支持孤立的微生物垫社区，否则贫瘠的高海拔景观和排放水形成了里奥萨拉多的源头，下游农村村庄的重要水资源。然而，El Tatio也是影响区域水质和水政策的有毒元素砷（As）和锑（Sb）的天然来源。As和Sb在该系统中的生物地球化学、微生物循环和最终移动性仍然是该生态系统和水资源的关键未知参数。 该项目将解决四个广泛的研究问题：什么是地球化学控制砷和锑的流动性？ 间歇泉流体成分的时空变化如何影响河口微生物群落？ 砷和锑是化学无机营养生物的化学能源，还是金属呼吸细菌的电子受体？ 锑、砷对硅质岩中的内石器时代生物群落有何影响？ El Tatio是一种独特的极端环境，不同于更深入研究的间歇泉区域;然而，与经典的热液系统相比，El Tatio几乎是未知的。 这个天然实验室提供了在非常高的浓度下原位研究As和Sb地球化学和直接观察基本地球化学关系的机会。 我们将使用跨学科的领域和实验室的地球化学和微生物的方法来描述间歇泉沃茨和硅灰岩（二氧化硅）中As和Sb氧化还原形态的地球化学控制。 这将包括使用分子和文化为基础的技术，栖息地水文地球化学和微生物群落组成的两个微生物群落和内石器时代的社区之间的关系的检查。 现场沉淀实验将补充实验室连续提取方法和热液二氧化硅沉淀实验，以检查As和Sb的分配行为。Sb同位素比将在水中和二氧化硅固体的特点，以测试潜在的微生物分馏。 排放量和化学成分的时间研究将用于估计有毒金属向下游社区的质量通量，El Tatio可以提供对地球地质系统中极端环境的微生物生态学的参数的深入了解。 在这个独特的硅质栖息地中，紫外线胁迫和有毒金属地球化学之间的关系也将为早期地球栖息地和生命起源提供深入了解。 此外，El Tatio对该地区村庄的影响涉及在保护不可替代的自然资源与了解有毒金属对水质的影响之间取得平衡。

EAR-0545336/EAR-0544960Philip C. BENNETT & Annette S. ENGELEl Tatio is one of the largest geyser zones known, with over 100 mapped hydrothermal features, and it is a cultural treasure and regional tourism resource for Chile Region II. Geyser water supports isolated microbial mat communities in the otherwise barren high altitude landscape and discharge water forms the headwaters of the Rio Salado, an essential water resource for downstream rural villages. El Tatio is also however a natural source of the toxic elements arsenic (As) and antimony (Sb) that impact regional water quality and water policy. The biogeochemistry, microbial cycling, and ultimate mobility of the As and Sb in this system remain as critical unknown parameters to this ecosystem and water resource. This project will address four broad research questions: What are the biogeochemical controls on As and Sb mobility? How do the spatial and temporal variations in geyser fluid composition influence lotic microbial communities? Are As and Sb used as sources of chemical energy for chemolithotrophs, or electron acceptors for metal-respiring bacteria? What are the influences of Sb and As on the endolithic communities in the geyserite? El Tatio is a uniquely extreme environment distinct from the more intensely studied geyser regions; yet, compared to the classic hydrothermal systems El Tatio is almost unknown. This natural laboratory offers the opportunity to study As and Sb biogeochemistry in situ at very high concentration and to directly observe fundamental geochemical relationships. We will characterize the biogeochemical controls on As and Sb redox speciation in the geyser waters and geyserite (silica) using interdisciplinary field and laboratory geochemical and microbiological methods. This will include an examination of the relationships between habitat hydro-geochemistry and microbial community composition of both the planktonic and endolithic communities using molecular- and culture-based techniques. Field precipitation experiments will be supplemented by laboratory sequential extraction methods and hydrothermal silica precipitation experiments to examine the partitioning behavior of As and Sb. Sb isotope ratios will be characterized in the water and silica solids to test for potential microbial fractionation. Temporal studies of discharge volume and chemical composition will be used to estimate the mass flux of toxic metals to the down stream communities.El Tatio can provide insight into the parameters that govern and define the microbial ecology of extreme environments in Earth's geologic systems. The relationship between UV stress and toxic metal biogeochemistry in this unique siliceous habitat will also provide insight into early-earth habitats and the origins of life. Further, the influence of El Tatio on the regional villages involves balancing preservation of an irreplaceable natural resource with understanding of the impacts of toxic metals on water quality.