Collaborative Research (USC/Caltech): Evaluation of Opal Dissolution Kinetics and Factors That May Regulate Opal Accumulation in Margin Sediments

碳和硅的海洋生物地球化学循环通过硅藻的活动直接联系在一起，因此，如果不确切了解是什么因素调节海洋硅的收支，就无法预测碳循环的行为。很明显，从海洋中去除硅主要是通过蛋白石（bSi =生物硅）埋葬，并已提出了几种算法，涉及bSi埋葬bSi雨率，在深海环境中的观测的基础上。不幸的是，这些算法具有有限的效用，因为我们没有一个机械的理解的因素联系到bSi溶解的bSi雨到达海底，因为他们不能在边缘环境中工作。边缘环境最近被认为是整个海洋中埋藏的30-45%的bSi的汇。沉积物积累的相对速率和bSi与铝硅酸盐相互作用的动力学似乎是调节bSi溶解的关键因素，尽管其他因素也可能发挥作用。在这项研究中，南加州大学和加州理工学院的研究人员将使用一种相对较新的技术，搅拌流反应器，来测量bSi溶解和边缘沉积物中Al释放的动力学，以评估这些因素如何影响硅化铋的埋藏。将对代表两个加州边界盆地整个颗粒输出路径的新收集样本（沉积物、落入陷阱的颗粒和沉积物）进行测量。结果将进行比较与动力学推导出从建模孔隙水剖面的酸和溶解铝。目标是开发一种算法的基础上容易测量的沉积物的特性，这将提供一个可靠的措施bSi埋藏的敏感性。这些信息将是有价值的解释的意义的bSi沉积记录和开发地球化学模型，将硅循环对碳动力学的影响。 该项目还将为研究生和本科生提供支助和培训。

ABSTRACTOCE - 0351169 / OCE - 0351498The marine biogeochemical cycles of carbon and silicon are directly linked through the activities of diatoms, so the behavior of the carbon cycle cannot be predicted without a firm understanding of what factors regulate the oceanic Si budget. It is clear that Si removal from the ocean occurs primarily through opal (bSi = biogenic silica) burial, and several algorithms that relate bSi burial to bSi rain rate have been proposed, based on observations in deep sea environments. Unfortunately, these algorithms have limited utility because we do not have a mechanistic understanding of the factors linking bSi dissolution to the bSi rain reaching the seabed, and because they fail to work in margin environments. Margin environments have recently been recognized as the sink for 30-45% of the bSi buried in the entire ocean. The relative rates of sediment accumulation and the kinetics of bSi interaction with aluminosilicates appear to be critical factors that regulate bSi dissolution, although other factors may play a role.In this study, researchers at the University of Southern California and the California Institute of Technology will use a relatively new technique, stirred flow reactors, to measure the kinetics of bSi dissolution and Al release from margin sediments, in an effort to evaluate how these factors may govern bSi burial. Measurements will be made on freshly collected samples (planktonic material, particles falling into traps, and the sediments) representing the entire particle export pathway in two California borderland basins. Results will be compared with kinetics deduced from modeling pore water profiles of silicic acid and dissolved Al. The goal is to develop an algorithm based on readily measured characteristics of sediments that will provide a reliable measure of bSi burial susceptibility. This information will be of value for interpreting the significance of the bSi sedimentary record and for developing biogeochemical models that incorporate the effect of the Si cycle on carbon dynamics. The project will also provide for the support and training of graduate and undergraduate students.