CAREER: Cryptic sulfur cycling and organic matter preservation in marine oxygen deficient zones

职业：海洋缺氧区的隐硫循环和有机物保存

• 批准号: 2143817
• 负责人: Morgan Raven
• 金额: $ 95.42万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2027-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2143817&HistoricalAwards=false
• 关键词: CAREER; Cryptic; sulfur; cycling; organic

CAREER: Particle-Hosted Sulfur Cycling and Organic Matter Burial in Oxygen Deficient Zones Areas of the ocean without dissolved oxygen are called anoxic zones. These environments are increasing due to human activities and climate change. Large amounts of organic carbon are buried in sediments below anoxic zones. However, we do not fully understand why organic carbon is preserved in these zones. This project seeks to understand a newly discovered process that may contribute to carbon preservation in anoxic zones. The process is called organic matter sulfurization. Through this process, organic matter is transformed and effectively ‘pickled’ by reacting with sulfide. Rapid sulfurization reactions were identified for the first time in sinking marine particles and may have larger effect on carbon burial in sediments than previously thought. This project will be the first to provide measurements of the scale and significance of rapid organic matter sulfurization in modern anoxic zones. This project includes field and laboratory studies. The research will involve a team of students, including a graduate student and six undergraduates, who will be supported through a peer mentorship program. Undergraduate researchers will be recruited from the inaugural class of a newly developed Practical Research Skills course (Earth 101A) at the University of California Santa Barbara. This course aims to make undergraduate research opportunities in the Earth Science Department more inclusive and accessible to minoritized students. It seeks to help undergraduates develop critical thinking and observational skills that have broad applicability. This project will launch a self-sustaining and vigorous research program in marine biogeochemistry, heavily invested in undergraduate research education, with impacts that will outlast its five-year duration.The overarching research goal of this project is to assess the contribution of sulfurization reactions to organic carbon preservation in anoxic environments. After constructing and testing a set of customized particle traps, an expedition will be conducted to the marine anoxic zone off the coast of Mexico. Sinking particles, suspended materials, and surface sediments will be collected at three sites on the Mexican shelf and slope, that have generally high local productivity and gradients in bottom-water oxygen concentration. In the field, the rates and isotopic fractionation of microbial sulfate reduction and organic sulfur formation will be measured with stable and radioactive isotope tracers. Subsequently, organic sulfur sources from both natural samples and laboratory experiments will be characterized using mass spectrometry, X-ray absorption spectroscopy, and other geochemical techniques. Together, the results of this work will identify the timing and location of organic matter sulfurization in this environment, which have substantial implications for both modeling marine carbon fluxes and interpreting the geologic record. This study will provide the first quantitative estimates of the scale of organic matter sulfurization in anoxic marine zones, its contribution to sedimentary carbon burial, and its sensitivities to environmental change. Simultaneously, this project will improve the Earth Science undergraduate curriculum at the University of California Santa Barbara through the development of a clear, supportive, and accessible mechanism for including students from diverse backgrounds in research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

职业：在不溶解氧气的海洋区域中，颗粒托管的硫磺循环和有机物埋葬被称为缺氧区域。由于人类活动和气候变化，这些环境正在增加。大量有机碳在缺氧区以下的沉积物中建造。但是，我们不完全理解为什么在这些区域中保存有机碳。该项目试图了解一个新发现的过程，该过程可能有助于缺氧区域的碳制备。该过程称为有机物硫化。通过此过程，有机物通过与硫化物反应来转化并有效地“腌制”。在沉没海洋颗粒中，首次鉴定出快速的硫化反应，并且对沉积物中的碳埋葬可能比以前想象的要大。该项目将是第一个对现代缺氧区域快速有机物硫化的规模和意义进行测量的项目。该项目包括现场和实验室研究。这项研究将涉及一组学生，包括一名研究生和六名本科生，他们将通过同伴心态计划得到支持。本科研究人员将从在加利福尼亚州圣塔芭芭拉分校的新开发的实用研究技能课程（Earth 101a）的就职课程中招募。本课程旨在使地球科学系的本科研究机会更具包容性，少数学生可以访问。它试图帮助大学生发展具有广泛适用性的批判性思维和观察能力。该项目将在海洋生物地球化学上启动一项自我维持和有力的研究计划，并在本科研究教育上投入了大量投资，其影响将超过其五年的持续时间。该项目的总体研究目标是评估硫化反应对缺氧环境中有机碳保存的贡献。在构建和测试了一组定制的颗粒陷阱之后，将向墨西哥沿海的海洋缺氧区进行探险。下沉的颗粒，悬浮材料和表面沉积物将在墨西哥架子和坡度上的三个地点收集，这些地点和坡度通常具有较高的局部生产力和底部水氧浓度的梯度。在现场，将使用稳定和放射性同位素示踪剂测量微生物硫酸盐还原和有机硫形成的速率和同位素分馏。随后，使用质谱，X射线抽象光谱和其他地球化学技术来表征来自天然样品和实验室实验的有机硫源。总之，这项工作的结果将确定在这种环境中有机物硫化的时机和位置，这对建模海洋碳通量和解释地质记录具有重大影响。这项研究将对缺氧海洋区域中有机物硫化的规模进行首次定量估计，其对沉积碳埋葬的贡献以及对环境变化的敏感性。同时，该项目将通过开发清晰，支持和可访问的机制来改善加利福尼亚圣塔芭芭拉分校的地球科学本科课程，以包括研究中的潜水员背景的学生。本奖反映了NSF的法定任务，并通过使用该基金会的智力优先级和广泛的影响来评估NSF的法定任务，并被认为是珍贵的支持。