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

边界清除是指放射性核素如钍-230 （Th230）和镤-231 （Pa231）在海洋边缘地区颗粒上的吸附增加；然而，这个过程并没有被很好地理解。231Pa/230Th的沉积物记录对解释过去的海洋环流和沉积物输运起着至关重要的作用，因此，限制这些放射性核素的边界清除成分具有重要意义。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，该项目将涉及一名研究生。计算代码将以对海洋科学界的其他研究人员有用的方式传播。目前对海洋中颗粒活性元素循环的边界清除过程的理解很差。一般采用简单的箱形模型，不能解释边界清除效应。本研究将采用高空间分辨率的区域模式，考虑海洋环流、泥沙输送和化学清除。该模型将用于限制控制Th-230和Pa-231海洋分布的过程，这两种放射性核素的比例已广泛用于研究过去的海洋环流。该模型将与GEOTRACES数据进行比较，以帮助改进模型，使项目符合GEOTRACES计划的两个最重要的目标。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。

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.