Collaborative Research: Iron and Manganese Depositing Cold-Seeps: Mineral Formation Along A Freshwater To Marine Ecosystem

合作研究：铁和锰沉积冷泉：淡水到海洋生态系统的矿物形成

• 批准号: 1420423
• 负责人: Craig Moyer
• 金额: $ 6.51万
• 依托单位: Western Washington University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1420423&HistoricalAwards=false
• 关键词: Collaborative; Research; Iron; Manganese; Depositing

This collaborative project examines the geochemistry and geomicrobiology of low-temperature iron-(Fe) and manganese-(Mn) rich carbonate ecosystems in Soda Bay, Alaska. These sites comprise numerous cold seeps and springs with bubbling waters containing carbon dioxide (CO2) that have proven to be very unusual in that they are also actively depositing Fe and Mn minerals, which in turn are harboring extensive microbial mat communities. The springs and seeps found within this unique watershed form along a salinity gradient with upstream being more freshwater while downstream has a tidally-driven marine influence. These habitats are sites where extensive microbial-mineral mounds (i.e., tufa deposits) form. Tufas as high as three meters are located along the length of both sides of Soda Bay Creek which drains into Soda Bay Estuary. The high flow systems are predominantly iron oxide deposition environments while the systems exhibiting low flow deposit manganese oxides. This project will investigate this unique watershed in an effort to describe the biogeochemistry and geomicrobiology of Fe- and Mn-mineral formation along the physicochemical gradients from the upper creek to Soda Bay. Researchers hypothesize that the mounds are autotrophic ecosystems hosting microorganisms able to grow and fix CO2 from the energy captured from metal oxidation reactions. They propose to examine the microbial ecology of these ecosystems with two primary questions in mind. First, what are the metabolic processes these microbes use to capture energy and thereby feed themselves? Second, how might these microbial communities (fueled by mineral and CO2-rich fluids) change in response to the physicochemical gradients? Answers to these questions will allow them to address future important questions relating to whether these environments preserve traces of microbial fossils or biosignatures that can show a historical presence and thereby provide a glimpse into the past. This is a new and potentially transformative investigation as there is virtually no information regarding the impact of low-temperature Fe- and Mn-rich groundwater on freshwater or marine ecosystems, whether such systems contribute to carbon fixation and the carbon cycle, or the energetic or metabolic basis of the microbes supporting these ecosystems.This project will partner with the Hydaburg School District. One of the researchers has built a longterm geoscience education and research program with the Hydaburg School District and Hydaburg Cooperative Association (tribal government) since 2008. The program involves 5th-12th grade science classes and teacher training with an emphasis on the interdisciplinary nature of the geosciences. Interested students have the opportunity to participate in field sampling and will interact with scientists during trips to Soda Bay. This project is closely coupled with local tribal groups that have a long history with this site. Researchers will, in turn, routinely share their scientific discoveries with the tribal organization.The project is well suited for EAGER support as it is exploratory in nature and potentially high impact. It will bring together multifaceted-technologies (e.g., aerial site survey, molecular biology, microscopy and geochemistry) in an effort to achieve a multi-scale understanding of this novel ecosystem potentially driven by metals as energy sources and where unique biogeochemical signatures will be preserved. Interpretation of such signatures in the geological record may provide new insights into important geological questions such as life in the ancient past, the role of microbes in the formation of metal ore deposits and even the evolution of life on Earth as the planet evolved from an anoxic to an oxic world. Ultimately, investigators hope to better predict how life now adapts to and mineralization occurs from interactions among these types of multi-dimensional strong gradient-driven environmental forcing functions.

该协作项目研究了阿拉斯加苏打水湾的低温铁（Fe）和锰（MN）富碳酸盐生态系统的地球化学和地球生物学。这些地点包含许多冷渗水和泉水，这些水域含有含二氧化碳（CO2）的气泡，这些水被证明是非常不寻常的，因为它们也在积极地沉积Fe和Mn矿物质，而Fe和Mn矿物质又具有广泛的微生物垫群落。在这种独特的分水岭形式中发现的弹簧和渗漏沿盐度梯度，上游更淡水，而下游具有潮汐驱动的海洋影响。这些栖息地是广泛的微生物矿物丘（即TUFA沉积物）形式的地点。高达三米的TUFA位于Soda Bay Creek两侧的长度上，该小溪流入苏打湾河口。高流量系统主要是氧化铁沉积环境，而表现出低流量沉积锰氧化物的系统。该项目将研究这个独特的流域，以描述从上溪到苏打湾的物理化学梯度沿物理化学梯度的Fe-和Mn矿物质形成的生物地球化学和地球生物学。研究人员假设这些土墩是托管能够从金属氧化反应中捕获的能量生长和固定CO2的微生物的自养生态系统。他们建议在考虑两个主要问题的情况下检查这些生态系统的微生物生态学。首先，这些微生物用来捕获能量并自我养活的代谢过程是什么？其次，这些微生物群落（矿物质和富含二氧化碳的液体都会助长物理化学梯度）如何变化？这些问题的答案将使他们能够解决与这些环境是否保留可以显示历史存在的微生物化石或生物签名的痕迹，从而对过去的瞥见。这是一项新的且潜在的变革调查，因为几乎没有关于低温Fe-和Mn富含地下水对淡水或海洋生态系统的影响的信息，无论是这些系统是否有助于碳固定和碳循环，还是支持这些生态系统的微生物的能量或代谢基础，都将与这些生态系统建立支持。自2008年以来，其中一名研究人员与Hydaburg学区和Hydaburg合作协会（部落政府）建立了长期的地球科学教育和研究计划。该计划涉及5年至12年级的科学课程和教师培训，并强调了地球科学的跨学科性质。有兴趣的学生有机会参与现场抽样，并将在前往苏打湾的旅行中与科学家互动。该项目与该网站历史悠久的当地部落团体紧密相结合。反过来，研究人员将经常与部落组织分享他们的科学发现。该项目非常适合急切的支持，因为它本质上是探索性的，并且潜在的影响很高。它将汇集多方面技术（例如，空中现场调查，分子生物学，显微镜和地球化学），以实现对这一新型生态系统的多规模理解，该新生态系统可能由金属作为能源作为能源和独特的生物地球化学特征保留在哪里。地质记录中这种特征的解释可能会为重要的地质问题（例如古代生活），微生物在金属矿石沉积物形成中的作用，甚至是地球上生命的演变而产生的新见解，因为地球从无毒的世界发展为毒性世界。最终，研究人员希望更好地预测生活如何适应和矿化是由于这些类型的多维强梯度驱动的环境强迫功能之间的相互作用发生的。