Collaborative Research: Dissolved Organic Matter Degradation in Filtering Shelf Sands

离散碳池的大小和周转时间的知识对于全球海洋碳动态的准确核算和建模至关重要。海洋溶解有机碳库（DOM）是地球上最大的可交换碳库之一，其产生或汇项可以强烈影响海洋和大气CO2之间的平衡或改变海洋沉积物中的碳储量。大陆架充当了大量DOM的水槽，这些DOM通过河流和陆地径流进入海洋。虽然陆源DOM的很大一部分是难降解的，但它不会在陆架和海洋中积累，这一过程尚不清楚，但对全球碳循环至关重要。在这项研究中，来自佛罗里达州立大学和北卡罗来纳大学教堂山分校的pi假设，含有DOM的沿海水被底部水流和波浪泵送通过可渗透大陆架沉积物的表层，迫使DOM通过具有大反应表面积和不同生物地球化学反应区的生物催化转化器。他们之前由美国国家科学基金会资助的研究表明，沉积物和水柱之间的酶水解率平均增加了200倍。本研究的具体目标是：1)量化墨西哥湾砂层和上覆水体中DOM的降解情况；2)评价孔隙流速、温度、氧浓度和光照对DOM分解速率的影响；3) FT-ICR-MS表征沉积物通道引起的DOM组成变化；4)量化代谢活性原核生物的丰度，建立DOM代谢与微生物群落系统发育组成之间的直接联系；5)将结果整合到一个将DOM降解率与孔隙水速度、温度、氧气和光线定量联系起来的经验模型中。更广泛的影响包括开发项目网站、公开讲座、向公众媒体发布新闻，以及向研究地点的FSU海洋实验室的访客分发信息材料。人力资源开发将通过本科生积极参与实地和实验室研究来加强，四名研究生将根据该研究的各个方面撰写论文。该项目将通过来自德国、荷兰和巴拿马的研究人员的积极参与，提高国际知名度和合作。

Knowledge of the sizes and turnover times of discrete pools of carbon is essential for accurate accounting and modeling of global ocean carbon dynamics. Production or sink terms of the oceanic pool of dissolved organic carbon (DOM), one of the largest exchangeable carbon reservoirs on earth, can strongly impact the balance between oceanic and atmospheric CO2 or change the storage of carbon in marine deposits. The continental shelf acts as sink for large quantities of DOM that reach the sea through rivers and runoff from land. Although a large fraction of the terrigenous DOM is refractory, it does not accumulate in the shelf and oceans, a process that is not well understood but is critical for the global cycles of carbon. In this research, PIs from Florida State University and University of North Carolina at Chapel Hill hypothesize that DOM laden coastal water is pumped through the surface layers of permeable shelf sediments by bottom currents and waves, forcing DOM through a biocatalytical converter with large reactive surface area and different biogeochemical reaction zones. Their prior NSF funded investigations showed an average 200-fold increase in enzymatic hydrolysis rates between sediments and water column. The specific objectives of the proposed research are 1) quantification of DOM degradation in filtering Gulf of Mexico sands and overlying water 2) assessment of the influences of pore flow velocity, temperature, oxygen concentration and light on DOM decomposition rates, 3) FT-ICR-MS characterization of DOM compositional changes caused by sediment passage and 4) quantification of the abundance of metabolically active prokaryotes and establishment of a direct linkage between DOM metabolism and the phylogenetic composition of microbial communities, 5) integration of the results into an empirical model that quantitatively relates DOM degradation rates to pore water velocity, temperature, oxygen and light. The broader impacts include development of a project web site, public lectures, news releases to the public media and information materials distributed to visitors of the FSU marine lab located at the study site. Human resource development will be enhanced through active participation of undergraduate students in field and laboratory research, and four graduate students will develop their theses based on aspects of this research. The project will enhance international visibility and collaboration through active participation of researchers from Germany, the Netherlands, and Panama.