Pa-231 and Th-230 in the Western North Atlantic: Disentangling the Effects of Boundary Scavenging and Ocean Circulation

北大西洋西部的 Pa-231 和 Th-230：解开边界清除和海洋环流的影响

• 批准号: 1556400
• 负责人: Olivier Marchal
• 金额: $ 55.34万
• 依托单位: Woods Hole Oceanographic Institution
• 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 2019-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1556400&HistoricalAwards=false
• 关键词: Pa; 231; Th; 230; Western

Boundary scavenging is the increased adsorption of radionuclides such as thorium-230 (Th230) and protactinium-231 (Pa231) onto particles in ocean margin areas; however, this process is not well understood. The sediment record of 231Pa/230Th has played a crucial role in interpreting past ocean circulation and sediment transport, and therefore, it is important to constrain the boundary scavenging component of these radionuclides. A researcher from Woods Hole Oceanographic Institution plans to develop a numerical model of ocean circulation, sediment transport, and particle scavenging to determine the processes that control the distribution of these two radionuclides in the Western North Atlantic. This study is particularly timely, since model observations will be tested using data collected as part of the ongoing GEOTRACES program. The results of this research will be incorporated into coursework taught at the Massachusetts Institute of Technology-Woods Hole Oceanographic Institution Joint Program in Oceanography, and the project will involve a graduate student. The computational codes will be disseminated in such a way that they can be useful to other researcher in the ocean sciences community.Current understanding of boundary scavenging processes on the cycling of particle-reactive elements in the ocean is poor. Simple box models are generally used, which cannot account for the boundary scavenging effects. This research will apply a high spatial resolution, regional model, taking into account ocean circulation, sediment transport, and chemical scavenging. The model will be used to constrain the processes that control oceanic distributions of Th-230 and Pa-231, two radionuclides the ratios of which have been extensively used in studying past ocean circulation. The model will be compared to GEOTRACES data for comparison and to help refine the model, placing the project in line with two of the overriding goals of the GEOTRACES program. The results from this project will be widely applicable to global ocean biogeochemical models that must account for boundary scavenging.

边界清除是指放射性核素如钍-230(Th230)和钚-231(Pa231)在海洋边缘地区的颗粒上的吸附增加；然而，这一过程尚未被很好地了解。231Pa230th的沉积物记录对解释过去的大洋环流和沉积物输运起到了至关重要的作用，因此，限制这些放射性核素的边界清除组分具有重要意义。伍兹霍尔海洋研究所的一名研究人员计划开发一个海洋环流、沉积物运输和颗粒清除的数值模型，以确定控制这两种放射性核素在北大西洋西部分布的过程。这项研究特别及时，因为模型观测将使用作为正在进行的GEOTRACES计划的一部分收集的数据进行测试。这项研究的结果将被纳入麻省理工学院-伍兹霍尔海洋研究所海洋学联合项目的课程中，该项目将涉及一名研究生。计算程序将以一种对海洋科学界其他研究人员有用的方式传播。目前对海洋中粒子反应元素循环的边界清除过程的了解很差。一般采用的是简单的箱体模型，不能考虑边界清除效应。这项研究将应用高空间分辨率的区域模式，考虑海洋环流、沉积物输送和化学清除。该模型将被用来约束控制海洋分布的Th-230和PA-231的过程，这两种放射性核素的比率在过去的海洋环流研究中得到了广泛的应用。该模型将与GEOTRACES的数据进行比较，以帮助改进模型，使该项目符合GEOTRACES计划的两个首要目标。该项目的结果将广泛适用于必须考虑边界清除的全球海洋生物地球化学模型。