Biogeochemical Cycling Of Barium In The Arabian Sea

福克纳海洋中任何微量元素的最大和最精确的数据库是钡的数据库，其浓度是在20世纪70年代作为GEOSECS计划的一部分在全球范围内测量的。通过这一努力，证实了Ba在海洋中经历了类似营养物的循环，并且它的行为更像是生物硬部分的成分（即Si和碱度），而不是它们组织的成分（即P和N）。对颗粒物质的研究表明，负责钡运输的主要相是矿物重晶石（BaSO4），它以某种方式在腐烂生物提供的微环境中沉淀，并倾向于积聚在高生产力带下的沉积物中。这种对钡循环的简单理解为其作为各种重要海洋过程的探索铺平了道路。例如，古ba分布，记录在有孔虫测试的方解石晶格中。正在被重建为通过冰期/间冰期转变对海洋环流变化的约束。在选定地点的年度带状珊瑚中，钡钙比已被提议监测与厄尔尼诺事件有关的上升流条件的变化。沉积钡被认为是上覆地表水古生产力的一个指标，在更直接的时间尺度上，水柱中的悬浮颗粒重晶石被认为提供了一个衡量从泛光带输出碳净速率的指标。虽然Ba作为一种调查工具的发展已经取得了相当大的进步，但要实现其全部潜力，需要对其在现代海洋中的行为有更彻底的了解。本研究将有助于溶解钡的分析，以解决海洋中钡循环的突出问题。此外，所产生的数据将用于与法国和比利时同事合作进行的印度洋和南冰洋模拟研究。

9311500 FALKNER The largest and most precise data base for any trace element in the oceans is that of barium whose concentrations were measured on the global scale as part of the GEOSECS program in the 1970's. From that effort, it was confirmed that Ba undergoes nutrient-like cycling in the oceans and that it behaves more like the constituents of the hard parts of organisms (i.e. Si and alkalinity) than those of their tissues (i.e. P and N). Work on particulate matter has shown that the principal phase responsible for the transport of Ba is the mineral barite (BaSO4), which is somehow precipitated in micro environments provided by decaying organisms and tends to accumulate in the sediments underlying zones of high productivity. This simple understanding of Ba cycling has paved the way for its development as a probe for a variety of important oceanic processes. For example, paleo-Ba distributions, as recorded in the calcite lattices of foraminifera tests. are being reconstructed as a constraint on changes in oceanic circulation through glacial/interglacial transitions. Barium to Ca ratios in annually banding corals at select locations have been proposed to monitor changes in upwelling conditions associated with El Nino events. Sedimentary Ba is thought to serve as an index of paleo-productivity in overlying surface waters and on a more immediate time-scale, suspended particulate barite in the water column has been suggested to provide a measure of the net rate of carbon export from the euphotic zone. While considerable strides in the development of Ba as an investigative tool have been made, realization of its full potential requires a more thorough understanding of its behavior in the modern ocean. This study will contribute dissolved Ba analyses to resolve outstanding issues regarding Ba cycling in the oceans. In addition, the data generated will be used in Indian and Antarctic Ocean modeling studies being conducted in collaboration with French and Belgian colleagues.