Methane, Ethylene, and Dissolved Organic Phosphorus Cycling in the Western North Atlantic Ocean

GSTDTAP

项目编号	1634080
	Methane, Ethylene, and Dissolved Organic Phosphorus Cycling in the Western North Atlantic Ocean
	Daniel Repeta
主持机构	Woods Hole Oceanographic Institution
项目开始年	2016
	2016-09-01
项目结束日期	2019-08-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	717000(USD)
国家	美国
语种	英语
英文摘要	The "marine methane paradox" refers to observations of high concentrations of methane in surface waters of the ocean, even though these waters are well-oxygenated and high in sulfate, both features which generally do not favor the production of methane. This project aims to elucidate on the cause of this paradox. Based on preliminary results, the investigator identified the potential for methane production stimulated by microbial cycling of dissolved organic matter. Polysaccharides (carbonates such as starch) are a major component of high molecular weight dissolved organic matter (HMWDOM) and they can incorporate esters of methylphosphonate, which may be allowing for the production of methane in surface waters. When these HMWDOM polysaccharides were introduced to seawater samples, the researchers saw production of methane with an anomalous stable carbon isotope ratio comparable to what is seen in the paradoxical surface waters enriched in methane. By making measurements of trace gases, HMWDOM phosphonate, and stable carbon isotope measurements in the western North Atlantic Ocean, the investigator and his collaborators will reassess the preliminary data and the implications of these results for the entire oceanographic cycling of methane. Both educational and outreach efforts have been included. For the educational component, a postdoc, a graduate student, and summer undergraduate students will be work on the project, whereas for the outreach activities, the proponent plans to develop curricula on basic science and oceanography for high school students, include a high school teacher in the research cruise, and integrate results into an organic geochemistry course, the lectures of which will be publically available online. This project seeks to evaluate the possibility that the "marine methane paradox", or the super-saturation of methane in high sulfate, well-oxygenated surface waters, is caused by microbial cycling of dissolved organic matter (DOM). There has been a great deal of preliminary evidence to support this theory. For example, samples from station ALOHA were amended with purified high molecular weight DOM (HMWDOM) polysaccharides, and methane, ethylene, and propylene productions were stimulated. HMWDOM polysaccharides incorporate esters of methylphosphonate (MPn), 2-hydroxyethylphosphonates (2-HEP), and other minor phosphonates, which are likely facilitating the production of methane, ethylene, and propylene. Carbon isotope data supports that this theory is the process behind the marine methane paradox; the d13C value of methane produced from HMWDOM polysaccharide enriched samples agrees well with the anomalous value associated with the super-saturated surface water. Only a small fraction of HMWDOM polysaccharides can easily explain the marine methane paradox, and this process could just as easily fully revise the current understanding of large scale methane cycling between the ocean and atmosphere. The researchers will assess the preliminary evidence and evaluate the microbial DOM cycling theory by making paired trace gas and HMWDOM phosphonate, as well as stable carbon isotope measurements in the western North Atlantic Ocean.
来源学科分类	Geosciences - Ocean Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/70333
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Daniel Repeta.Methane, Ethylene, and Dissolved Organic Phosphorus Cycling in the Western North Atlantic Ocean.2016.