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：缺氧区中的颗粒硫循环和有机物埋藏海洋中没有溶解氧的区域称为缺氧区。由于人类活动和气候变化，这些环境正在增加。大量的有机碳埋藏在缺氧区下面的沉积物中。然而，我们并不完全理解为什么有机碳被保存在这些区域。该项目旨在了解一种新发现的可能有助于缺氧区碳保存的过程。这个过程被称为有机物硫化。通过这一过程，有机物被转化，并通过与硫化物反应而有效地“酸洗”。快速硫化反应首次被确定在下沉的海洋颗粒，并可能有更大的影响碳埋藏在沉积物中比以前认为的。该项目将首次提供现代缺氧区快速有机物硫化的规模和意义的测量。该项目包括实地和实验室研究。这项研究将涉及一个学生团队，包括一名研究生和六名本科生，他们将通过一个同伴导师计划得到支持。本科研究人员将从加州大学圣巴巴拉新开发的实用研究技能课程（地球101 A）的首届课程中招募。本课程旨在使地球科学系的本科生研究机会更具包容性，并使少数民族学生更容易获得。它旨在帮助本科生发展具有广泛适用性的批判性思维和观察技能。该项目将启动一个自我维持和充满活力的海洋生物地球化学研究计划，大量投资于本科研究教育，其影响将持续五年的时间。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。在建造和测试了一套定制的颗粒捕集器后，将对墨西哥海岸的海洋缺氧区进行考察。将在墨西哥大陆架和斜坡上的三个地点收集下沉颗粒、悬浮物和表层沉积物，这些地点一般具有较高的当地生产力和底层水氧浓度梯度。在现场，将用稳定的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，将使用质谱法、X射线吸收光谱法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间和位置，这对海洋碳通量建模和解释地质记录都有重大意义。这项研究将首次定量估计缺氧海洋区有机质硫化的规模、其对沉积碳埋藏的贡献及其对环境变化的敏感性。同时，该项目将通过发展一个明确的、支持性的和可访问的机制来改善加州圣巴巴拉大学的地球科学本科课程，该机制将来自不同背景的学生纳入研究。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。