CAREER: The Importance of Iron in the Remineralization of Organic Matter in Estuarine and Continental Shelf Sediments

沿海和海洋沉积物中有机碳的命运和转化对于理解碳循环及其对全球气候变化的影响至关重要。该项目旨在通过原位技术和数学模型研究河口和大陆架沉积物中天然有机质（NOM）转化的机制。本研究基于以下两个假设：1)微生物Fe（III）还原在靶区NOM再矿化中占很大一部分；2)通过生物扰动提供足够的氧气，使Fe(OH)3有效地循环用于NOM再矿化。该项目提出构建一个由底栖生物室、微操纵器和伏安微电极组成的着陆器系统，以获取原位底栖生物通量数据和微剖面。该原位数据结合沉积物岩心的硫酸盐还原速率、固相和孔隙水数据以及反应器实验结果将用于计算NOM再矿化速率。然后，PI提出建立一个三维成岩模型来预测大陆架和河口沉积物中的NOM再矿化。将化学家和工程师纳入化学海洋学领域是教育部分的四个目标之一。PI建议让这些领域的学生参与着陆器系统的开发和建模工作。此外，作为GIT现有项目的一部分，一名高中教师将在夏季在PI的实验室进行一项研究项目。第三个组成部分需要发展现有地球化学课程的实验室组成部分。这个实验室组成部分将包括在R/V萨凡纳上巡航，部署着陆器系统，并让学生参与拟议研究的实地和实验室工作。第四个组成部分包括一个学生交换计划，涉及GIT、Skidaway海洋学研究所和欧洲合作伙伴。

ABSTRACTOCE-0239376The fate and transformation of organic carbon in coastal and marine sediments is intrinsic to understanding the carbon cycle and its influences on global climate change. The objective of the proposed research by the PI was to examine the mechanisms of natural organic matter (NOM) transformation in estuarine and continental shelf sediments through in-situ technology and mathematical modeling. The research is based on the following two hypotheses: 1) microbial Fe(III) reduction accounts for a significant portion of NOM remineralization in the target regions, and 2) sufficient oxygen is supplied through bioturbation to recycle Fe(OH)3 efficiently for NOM remineralization. The PI proposed to construct a lander system with a benthic chamber, a micromanipulator and voltammetric microelectrodes to obtain in situ benthic flux data and microprofiles. This in situ data combined with sulfate reduction rates, solid phase and porewater data from sediment cores, and results from reactor experiments would be used to calculate NOM remineralization rates. The PI then proposed to develop a 3-D diagenetic model to predict NOM remineralization in continental shelf and estuarine sediments.Incorporating chemists and engineers into the chemical oceanography field was one of four objectives of the educational component. The PI proposed to involve students in these fields in the development of the lander system and the modeling effort. Additionally, a high school teacher would conduct a research project in the PI's laboratory during the summer as part of an existing program at GIT. The third component entailed development of a laboratory component of an existing Geochemistry course. This laboratory component would include cruises on the R/V Savannah to deploy the lander system and involve the students in the field and laboratory efforts of the proposed research. The fourth component consisted of a student exchange program involving GIT, Skidaway Institute of Oceanography, and European partners.