Collaborative Proposal: Anoxic Sediment Diagenesis at the Sulfate-Methane Interface: Does a Novel Microbial Syntrophy Result in Enhanced POC Remineralization?

大陆边缘沉积物中的有机碳分解或成岩作用是海洋沉积物中碳循环的重要组成部分，其程度控制着长期埋藏速率。来自南加州大学、加州理工学院和夏威夷大学的科学家们假设了一种新的成岩过程，当硫酸盐和甲烷同时存在时，可能会导致碳再矿化的增强。根据初步数据，这一过程似乎发生在一个局部的水平层（厘米厚），在那里古细菌和硫酸盐还原细菌对甲烷的厌氧氧化之间存在微生物共生关系。他们将使用高分辨率孔隙水测量来研究圣巴巴拉盆地的沉积物，以创建化学梯度模型并计算扩散通量值。微生物群落将使用总微生物细胞计数，古细菌和细菌16S rDNA和基于dsrabb的群落特征，以及荧光原位杂交（FISH）来描述。操纵培养实验将尝试通过添加硫酸盐和/或甲烷来诱导更高的碳再矿化率。这一独特带在缺氧海洋沉积物中的重要性，对目前碳成岩作用的建模方法、海洋沉积物古代用记录的解释以及对沉积物微生物群落生态学的一般理解具有潜在的重要意义。一名微生物学家和两名地球化学家的合作，将向广泛的学生展示跨学科研究所产生的协同效应，包括REU，初中和高中学生，以及参与这次合作的研究生和本科生，在邮轮和数据分析方面。

ABSTRACT - Berelson 0433322Organic carbon breakdown, or diagenesis, within continental margin sediments is an important component of the C cycle in marine sediments as its extent controls long-term burial rates. Scientists from University of Southern California, California Institute of Technology and University of Hawaii have hypothesized a novel diagenetic process that may result in enhanced carbon remineralization when both sulfate and methane are present. Based on preliminary data, this process appears to occur at a localized horizon (cm's thick) where there is a microbial syntrophic relationship between anaerobic oxidation of methane by archaea and sulfate reducing bacteria. They will study sediments of the Santa Barbara Basin using high-resolution pore water measurements to create models of the chemical gradients and calculate diffusive flux values. The microbial community will be described using total microbial cell counts, archaeal and bacterial 16S rDNA and dsrAB-based community characterization, and fluorescent in situ hybridization (FISH). Manipulative incubation experiments will attempt to induce higher rates of carbon remineralization by the addition of sulfate and or methane. The importance of this unique zone in anoxic marine sediments has potentially significant implications to current modeling approaches to carbon diagenesis, interpretation of paleoproxy records in marine sediments and to general understanding of sediment microbial community ecology. Collaboration between a microbiologist and two geochemists will illustrate the synergies created by interdisciplinary research to a wide range of students including REU, middle and high school students, as well as the graduate and undergraduate students participating in this collaboration on cruises and in data analysis.