Transient Diagenesis in Organic Poor Sediments: Lake Superior

有机质贫乏沉积物中的瞬时成岩作用：苏必利尔湖

• 批准号: 0961720
• 负责人: Sergei Katsev
• 金额: $ 41.7万
• 依托单位: University of Minnesota Duluth
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0961720&HistoricalAwards=false
• 关键词: Transient; Diagenesis; Organic; Poor; Sediments

In this project, researchers at the University of Minnesota at Duluth will investigate the geochemistry of organic carbon, nitrogen, phosphorous, and iron in the sediments of Lake Superior and quantify their temporal and spatial variability. The geochemical budgets of nitrogen and phosphorus in Lake Superior are presently unbalanced, and major trends in nutrient concentrations and primary productivity remain unexplained. The researchers' preliminary data suggest that the sediments of Lake Superior have experienced large vertical migrations in the depth of oxygen penetration, analogous to those implicated in organic-poor sediments in the deep ocean. Given the importance of redox conditions for the sediment nutrient recycling, they hope to elucidate the seasonal and multi-decadal responses of these sediments to the temporal changes in water column chemistry and biological productivity. The specific objectives are: (1) to characterize the geochemistry of organic carbon, nitrogen, phosphorus, and iron in Lake Superior sediments and quantify their temporal and spatial variability; (2) to simulate the diagenetic biogeochemical cycling in the lake and calculate the in situ rates of the organic carbon mineralization pathways and sediment-water nutrient fluxes at sites with different oxygen penetrations; (3) to elucidate seasonal and multi-decadal sediment responses to variations in the organic carbon sedimentation and bottom water concentrations of oxygen and nitrate, and quantify sediment contributions to the water column N and P budgets; and (4) to gain insights into the causes, consequences, and the dynamics of the increasing N:P imbalance in Lake Superior. These objectives will be accomplished using direct measurements of geochemical parameters in the lake and sediment incubations. Results will be integrated into sediment reactive-transport models and mass-balance water column models for examination of in situ process rates, reconstructions of past dynamics, and future projections. Broader Impacts: Arguably, study of these phenomena in Lake Superior will advance understanding of geochemical dynamics in other carbon-limited sediments. The sediment chemistry models developed will contribute to the ongoing system-wide modeling efforts in Lake Superior, will serve the large community of Lake Superior researchers, and will be transferable to other environments. Graduate and undergraduate students will be included on the research team.

在这个项目中，明尼苏达大学杜卢斯分校的研究人员将调查上级湖沉积物中有机碳、氮、磷和铁的地球化学，并量化其时空变异性。 苏必利尔湖上级的氮和磷的地球化学收支目前是不平衡的，营养物浓度和初级生产力的主要趋势仍然无法解释。 研究人员的初步数据表明，上级湖的沉积物在氧气渗透深度经历了大规模的垂直迁移，类似于深海中有机物贫乏的沉积物。考虑到氧化还原条件对沉积物养分循环的重要性，他们希望阐明这些沉积物对水柱化学和生物生产力随时间变化的季节性和数十年的响应。具体目标是：（1）研究苏必利尔湖上级沉积物中有机碳、氮、磷和铁的地球化学特征及其时空变异性，（2）模拟苏必利尔湖成岩地球化学循环，计算不同氧渗透率下的有机碳矿化途径速率和沉积物-水营养盐通量;（3）阐明沉积物对有机碳沉积和底层水中氧和硝酸盐浓度变化的季节性和数十年的响应，并量化沉积物对水柱N和P收支的贡献;（4）深入了解N增加的原因、后果和动态：苏必利尔湖上级磷失衡。这些目标将通过直接测量湖泊和沉积物孵化中的地球化学参数来实现。研究结果将被整合到沉积物反应传输模型和质量平衡水柱模型中，以研究原位过程速率、重建过去的动态和未来的预测。更广泛的影响：可以说，对苏必利尔湖上级这些现象的研究将促进对其他碳有限沉积物中地球化学动力学的理解。 沉积物化学模型的开发将有助于正在进行的系统范围内的建模工作在苏必利尔湖上级，将服务于大型社区的苏必利尔湖上级的研究人员，并将转移到其他环境。 研究生和本科生将包括在研究团队。