Collaborative Research: Shallow-sea hydrothermal systems: Micron-scale sedimentary sulfur cycling and its impact on ocean processes

合作研究：浅海热液系统：微米级沉积硫循环及其对海洋过程的影响

• 批准号: 1261424
• 负责人: Gregory Druschel
• 金额: $ 10.17万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1261424&HistoricalAwards=false
• 关键词: Collaborative; Research; Shallow; sea; hydrothermal

The influx of reducing (i.e., anoxic) fluids through deep-sea and shallow-sea hydrothermal systems into the ocean plays a major role in determining ocean chemistry and its evolution over geologic history. The interface between hydrothermal fluids and the overlying cool and well-oxygenated seawater is characterized by intense thermodynamic disequilibrium, driving a suite of biogeochemical reactions, which in turn further shape ocean chemistry. These reactions generate strong geochemical redox gradients transitioning from the marine water column into the sediments beneath along the interface with reducing hydrothermal fluids. These gradients provide a framework where microbial communities live, evolve, shape, and are shaped by their local geochemical environment. However, the link between the metabolic activity of these micron-sized microorganisms and the resulting geochemical signatures (typically sampled at approximately cm-scale resolution) remains elusive, in large part because of the difficulty of extracting sufficient material for geochemical analyses at small scales (~1-100 microns). Yet, it is precisely this fine-scale geochemical variability that directly impacts biogeochemical activity. This research takes advantage of recent advances in analytical techniques that allow for geochemical and stable isotopic measurements at a spatial resolution as small as ~1-10 microns. Samples come from accessible shallow-sea hydrothermal systems in the Mediterranean Sea, where diverse sulfur cycling has been previously identified and steep redox gradients make it possible for micron-scale measurements to sample across a wide range of geochemical environments. In addition, a 20+-year record of observations allows the results to be put into a rich geochemical context. Goals are to generate an unparalleled high-resolution geochemical and isotopic characterization of sulfur cycling in shallow-sea hydrothermal systems and use the resulting data to calculate the thermodynamic drivers for diverse biogeochemical reactions. The data will also allow the evaluation of the role of ambient geochemistry on isotopic fractionation during sulfur biogeochemical cycling and application of results to understanding variations in the isotopic composition of sulfur species in marine sediments through time because sulfur isotopes are one of the principle means to reconstruct paleoenvironmental conditions over Earth history. Broader impacts of the work include undergraduate and graduate student training in the field and laboratory. Cross training in different laboratories will also deepen the integration of research and education. This project also involves international collaboration with Sicilian and German scientists.

通过深海和浅水热液系统减少（即缺氧）流体的涌入（即缺氧）在确定海洋化学及其在地质历史上的进化方面起着重要作用。 水热流体与上覆的凉爽和氧化的海水之间的界面的特征是强烈的热力学不平衡，驱动了一套生物地球化学反应，从而进一步塑造了海洋化学。这些反应产生了强大的地球化学氧化还原梯度，从船舶水柱转变为沿界面下方的沉积物，并减少热液流体。这些梯度提供了一个框架，其中微生物群落的生存，发展，形状并受其当地地球化学环境的影响。 然而，这些微米大小的微生物的代谢活性与所得的地球化学特征（通常以大约CM尺度分辨率采样）之间的联系仍然难以捉摸，这在很大程度上是由于难以提取足够的材料来在小尺度上提取足够的材料来进行地球化学分析（〜1-100 microns）。然而，正是这种高尺度的地球化学变异性直接影响生物地球化活性。 这项研究利用了分析技术的最新进展，这些技术允许在短达〜1-10微米的空间分辨率下进行地球化学和稳定的同位素测量。 样品来自地中海的可访问浅海水热系统，以前已经鉴定出多种硫循环，并且陡峭的氧化还原梯度使微米尺度的测量可以在各种地球化学环境中进行采样。 此外，观察结果20+年的记录可以使结果置于丰富的地球化学环境中。 目标是生成无与伦比的高分辨率地球化学和同位素表征，对浅水热液系统中的硫循环，并使用所得数据计算热力学驱动因素，以进行多种生物地球化学反应。 数据还将允许评估环境地球化学对硫生物地球化学循环过程中同位素分馏的作用，并应用结果对通过时间通过时间的硫化物质的同位素组成的变异来了解，因为硫同位素是硫同位素，因为硫同位素是重新建构古环境条件的原理之一。 这项工作的更广泛影响包括本科和实验室的本科生和研究生培训。 不同实验室的交叉培训还将加深研究和教育的整合。 该项目还涉及与西西里和德国科学家的国际合作。