Collaborative Research: Are Carbon Fluxes from Marine Sediments Enhanced by Submarine Ground Water Discharge?

合作研究：海底地下水排放是否增强了海洋沉积物中的碳通量？

• 批准号: 0403842
• 负责人: Jennifer Cherrier
• 金额: --
• 依托单位: Florida Agricultural and Mechanical University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0403842&HistoricalAwards=false
• 关键词: Collaborative; Research; Carbon; Fluxes; Marine

0403842CherrierThe flux of C from coastal marine sediments is likely to be influenced by submarine ground water discharge (SGD), which may enhance remineralization of buried C and transport it to the water column. Previous studies reveal that SGD includes both meteoric water from continental aquifers and surface water mixed into shallow sediment through processes such as wave and tidal pumping, density driven flow, and bioirrigation. Surface water is saturated with oxygen, and thus should remineralize organic carbon that otherwise would be sequestered in the sediments. The process of mixing and enhanced remineralization will be studied in the Indian River Lagoon System (eastern Florida), where changes in water column salinity and pore waters have been used previously, and will be used in this study, to trace pumping of oxygenated surface water into the sediments. The study will use time-series measurements and monitoring of conservative tracers (conductivity, Cl- concentration, 222Rn activity, and temperature) to determine the temporal and spatial scales of mixing, as well as variations through time and space of discharge from the regional aquifers. Combining Cl- and conductivity allows greater temporal and spatial resolution than either one alone. Simultaneous measurements of Cl- concentration, conductivity, and 222Rn activity provide unique information because of their distinct compositions in end-member water sources. The hydrologic studies will be coupled with studies of remineralization of C in the sediments using C concentrations and 13C and 14C as tracers of the sources of C. Carbon in the mixed zone will be depleted in 14C because detrital organic carbon will be up to several thousand years old depending on depth of burial. Carbon in the meteoric water will be even more depleted in 14C depending on the flow paths and rates. The d13C values will be controlled by the source of C from carbonate or organic matter and provides a powerful complement to the 14C measurements. Results of the study should provide information on the efficiencies of C transformation, spatial and temporal variations of hydrologic controls on those transformations and fluxes in coastal sediments, and information on C cycling in marine sediments from hydrologic processes, an important first step toward quantitative estimates of sources to the global C cycle. The study will also develop new isotopic tracing techniques to study these processes. The study has important management implications for the local study site, which is in the National Estuaries Program, is one of the most biologically diverse estuaries in the nation, and home to 21 endangered or threatened species. The project impacts the educational missions of the University of Florida (a Research I institution), Florida A&M University (a Historically Black and Minority Serving College/University), and Louisiana State University (located in an EPSCoR state) through involvement of high school to graduate students, both through course work that will be linked to the Florida Center for Ocean Science Education Excellence (FCOSEE) web portal, and directly in the project, which offers a broad range of learning opportunities (hydrology and biogeochemistry).

0403842Cherrier沿海海洋沉积物中的碳通量可能受到海底地下水排放（SGD）的影响，这可能会增强埋藏碳的再矿化并将其输送到水体中。 先前的研究表明，SGD 包括来自大陆含水层的大气水和通过波浪和潮汐抽水、密度驱动流和生物灌溉等过程混合到浅层沉积物中的地表水。 地表水的氧气饱和，因此应该使有机碳再矿化，否则这些有机碳将被隔离在沉积物中。 将在印第安河泻湖系统（佛罗里达州东部）研究混合和增强再矿化的过程，该系统之前已使用水柱盐度和孔隙水的变化，并将在本研究中使用，以跟踪含氧地表水的泵送进入沉积物。 该研究将使用时间序列测量和保守示踪剂（电导率、Cl-浓度、222Rn 活性和温度）监测来确定混合的时间和空间尺度，以及区域含水层排放随时间和空间的变化。 。 将 Cl- 和电导率结合起来比单独使用任何一种都可以获得更高的时间和空间分辨率。 同时测量 Cl- 浓度、电导率和 222Rn 活度可提供独特的信息，因为它们在端元水源中的成分不同。 水文研究将与沉积物中碳的再矿化研究相结合，使用 C 浓度以及 13C 和 14C 作为 C 来源的示踪剂。混合区的碳将在 14C 中耗尽，因为碎屑有机碳将高达数千年龄取决于埋葬深度。 根据流动路径和速率，大气中的碳在 14C 时会更加消耗。 d13C 值将由碳酸盐或有机物中的 C 来源控制，并为 14C 测量提供有力的补充。 研究结果应提供有关碳转化效率的信息、沿海沉积物中这些转化和通量的水文控制的空间和时间变化以及水文过程中海洋沉积物中碳循环的信息，这是定量估计碳的重要第一步。全球 C 循环的来源。 该研究还将开发新的同位素示踪技术来研究这些过程。 该研究对当地研究地点具有重要的管理意义，该研究地点属于国家河口计划，是全国生物多样性最丰富的河口之一，也是 21 种濒危或受威胁物种的家园。 该项目通过高中的参与，影响佛罗里达大学（一所研究机构）、佛罗里达农工大学（一所历史悠久的黑人和少数族裔服务学院/大学）和路易斯安那州立大学（位于 EPSCoR 州）的教育使命研究生，既可以通过与佛罗里达海洋科学教育卓越中心 (FCOSEE) 门户网站链接的课程作业，也可以直接参与该项目，该项目提供了广泛的学习机会（水文学和生物地球化学）。