The Behavior and Distribution of Particle-Reactive Radionuclide Tracers in Particulates, Colloids, and Solution in the Canada Basin of the Arctic Ocean

这项提议是为了调查一系列元素的行为，这些元素为北冰洋加拿大盆地的颗粒去除过程提供同位素示踪剂。这些核素包括U和Th系列核素、Nd和Pu。将强调颗粒、胶体和溶液之间的分配的作用。与其他海洋相比，该区域的颗粒通量特别低，这至少有两个原因：(1)这是北冰洋的一个基本特征，需要更好地了解它对颗粒反应性污染物同化的影响；(2)仔细描述这一极端情况下的过程将为其他研究提供一个重要的参照点。这项建议纳入了目前关于胶体大小的颗粒在通过清除去除痕量金属方面的作用的想法，这是拟议工作的一个重要重点。需要检验的假设如下：“由于加拿大盆地的颗粒浓度较低，胶体在颗粒反应性放射性核素的循环中起着主要作用。”早期对溶解有机碳和悬浮颗粒浓度(SPM)的研究表明，加拿大盆地的胶体物质浓度可能与其他主要洋盆相似，而SPM浓度大约比其他洋盆低一个数量级。为了验证这一假设，本研究将沿着以下研究路线进行：1.将测量加拿大盆地水柱中长寿命TH同位素和短寿命同位素在颗粒、胶体和溶解物种之间的分布，包括大陆架、斜坡和深盆地。通过微粒清除铅和Po的清除率将根据它们在水柱中的测量来计算，以便与Th的清除进行比较。2.测量了Nd同位素在颗粒、胶体和溶解物种之间的分布。3.将在不同地点测量溶解和颗粒状PU同位素在水柱中的分布，并通过与其他颗粒反应性核素的比较来研究它们的迁移和清除速率。这项研究的一个关键方面是将Th的短寿命同位素与长寿命的Th同位素和稳定的Nd同位素的数据结合起来。

This proposal is to investigate the behavior of a range of elements that provide isotopic tracers for particle removal processes in the Canada Basin of the Arctic Ocean. These will include U- and Th-series nuclides, Nd and Pu. The role of partitioning between particulates, colloids, and solution will be emphasized. This region is unique in having exceptionally low particle fluxes compared with other oceans for at least two reasons: (i) It is a fundamental characteristic of the Arctic Ocean that needs to be better understood along with the implications it has for the assimilation of particle-reactive contaminants, and (ii) a careful characterization of the processes in this extreme case will provide an important reference point for other studies. This proposal incorporates current ideas about the role of colloid-size particles in the removal of trace metals by scavenging and this is an important focus of the proposed work. The hypothesis to be tested is as follows: "Due to low particle concentration in the Canada Basin, the colloids play a major role in the cycling of particle-reactive radionuclides." Earlier studies on the dissolved organic carbon and suspended particle concentration (SPM) indicate that the concentration of colloidal material in Canada Basin is likely similar to other major ocean basins while the SPM concentration is about an order of magnitude lower than that of other ocean basins. In order to test the hypothesis, the study will focus along the following lines of investigation: 1. The distribution of the long-lived TH isotopes and short-lived isotopes between particles, colloids, and dissolved species will be measured in the Canada Basin water column in both continental shelf, slope and deep basin. The removal rate by particulate scavenging of Pb and Po will be calculated from their measurement in the water column for comparison with the removal of Th. 2. The distribution of Nd isotopes between particles, colloids and the dissolved species will be m easured. 3. The distribution of dissolved and particulate PU isotopes in the water column will be measured at various sites and their rates of transport and removal will be investigated by comparison with other particle-reactive nuclides. A key aspect of the study is the combining of data for the short-lived isotopes of TH with the long lived Th isotopes and stable Nd isotopes.