The biotic and abiotic controls on the Silicon cycle in the northern Gulf of Mexico

墨西哥湾北部硅循环的生物和非生物控制

• 批准号: 1558957
• 负责人: Jeffrey Krause
• 金额: $ 47.81万
• 依托单位: Marine Environmental Sciences Consortium
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1558957&HistoricalAwards=false
• 关键词: biotic; abiotic; controls; Silicon; cycle

The Louisiana Shelf system in the northern Gulf of Mexico is fed by the Mississippi River and its many tributaries which contribute large quantities of nutrients from agricultural fertilizer to the region. Input of these nutrients, especially nitrogen, has led to eutrophication. Eutrophication is the process wherein a body of water such as the Louisiana Shelf becomes enriched in dissolved nutrients that increase phytoplankton growth which eventually leads to decreased oxygen levels in bottom waters. This has certainly been observed in this area, and diatoms, a phytoplankton which represents the base of the food chain, have shown variable silicon/nitrogen (Si/N) ratios. Because diatoms create their shells from silicon, their growth is controlled not only by nitrogen inputs but the availability of silicon. Lower Si/N ratios are showing that silicon may be playing an increasingly important role in regulating diatom production in the system. For this reason, a scientist from the University of South Alabama will determine the biogeochemical processes controlling changes in Si/N ratios in the Louisiana Shelf system. One graduate student on their way to a doctorate degree and three undergraduate students will be supported and trained as part of this project. Also, four scholarships for low-income, high school students from Title 1 schools will get to participate in a month-long summer Marine Science course at the Dauphin Island Sea Laboratory and be included in the research project. The study has significant societal benefits given this is an area where $2.4 trillion gross domestic product revenue is tied up in coastal resources. Since diatoms are at the base of the food chain that is the biotic control on said coastal resources, the growth of diatoms in response to eutrophication is important to study.Eutrophication of the Mississippi River and its tributaries has the potential to alter the biological landscape of the Louisiana Shelf system in the northern Gulf of Mexico by influencing the Si/N ratios below those that are optimal for diatom growth. A scientist from the University of South Alabama believes the observed changes in the Si/N ratio may indicate silicon now plays an important role in regulating diatom production in the system. As such, understanding the biotic and abiotic processes controlling the silicon cycle is crucial because diatoms dominate at the base of the food chain in this highly productive region. The study will focus on following issues: (1) the importance of recycled silicon sources on diatom production; (2) can heavily-silicified diatoms adapt to changing Si/N ratios more effectively than lightly-silicified diatoms; and (3) the role of reverse weathering in sequestering silicon thereby reducing diffusive pore-water transport. To attain these goals, a new analytical approach, the PDMPO method (compound 2-(4-pyridyl)-5-((4-(2-dimethylaminoethylamino-carbamoyl)methoxy)phenyl)oxazole) that quantitatively measures taxa-specific silica production would be used.

墨西哥北部海湾的路易斯安那州货架系统由密西西比河及其许多支流提供，这些支流从农业肥料到该地区贡献了大量养分。 这些营养素的输入，尤其是氮，导致了富营养化。 富营养化是一种过程，其中的水体（如路易斯安那州的架子）富含溶解的营养物质，从而增加浮游植物的生长，最终导致底部水域的氧气水平降低。 当然，在该区域已经观察到了这一点，而代表食物链基础的植物硅藻显示了可变的硅/氮（Si/N）比。 由于硅藻从硅产生壳，因此它们的生长不仅受氮输入，而且由硅的可用性控制。 较低的Si/N比率表明，硅在调节系统中的硅藻生产中可能起着越来越重要的作用。 因此，南阿拉巴马大学的科学家将确定控制路易斯安那州货架系统中SI/N比的变化的生物地球化学过程。 在该项目的一部分中，一名研究生将获得博士学位，三名本科生将得到支持和培训。 此外，来自标题1学校的低收入高中生的四项奖学金将在Dauphin Island Sea Laboratory参加为期一个月的夏季海洋科学课程，并将其包括在研究项目中。 这项研究具有重大的社会利益，鉴于这是沿海资源捆绑2.4万亿美元的国内生产总收入的领域。 由于硅藻是对所述沿海资源的生物控制的食物链的基础，因此响应富营养化的硅藻的生长对于研究很重要。密西西比河及其支流的繁殖力有可能通过在墨西哥北方北部的北方n nortiat for deiat for dy cartiiat th dy cartiios diat cartiios dy cartiios dy cartiios diat cartiios diat cartiioos dy cartiios diat cartiios。 南阿拉巴马大学的一位科学家认为，观察到的Si/N比率的变化可能表明硅现在在调节系统中的硅藻生产中起着重要作用。 因此，了解控制硅周期的生物和非生物过程至关重要，因为在这个高生产力的地区，硅藻在食物链的底部占主导地位。 该研究将重点介绍以下问题：（1）回收硅源对硅藻生产的重要性； （2）比轻硅化的硅藻更有效地适应Si/n比变化的大量硅藻； （3）反向风化在隔离硅中的作用，从而减少了扩散的孔隙水运输。 为了实现这些目标，一种新的分析方法，PDMPO方法（化合物2-（4-吡啶基）-5 - （（（4-（4-（2-二甲基氨基氨基氨基 - 核酰基））甲氧基苯基苯基苯基苯基苯基）苯基苯唑）的定量测​​量可用于使用特定于特异性的二氧化硅的生产。