(EGB) Evaluating the Processes Governing Particle-Reactive Element Transport in an Arctic River System: Coupling Hydrology, Geochemical Tracers, and Hydrologic Models

我们提出了一种跨学科的方法来评估沉积物和与颗粒相关的污染物在河流中的迁移，这种方法适用于许多测量稀少的河流主导的沿海系统。为了克服数据限制和覆盖大空间尺度，我们建议联合使用化探、水动力学和水文数据集以及高分辨率的运移和地球化学过程模型。我们的目标是提供有关运输和沉积环境的路径、动力学和控制的基本信息，并探索系统对污染物负荷和积累的敏感性。这项研究的一个非常重要的方面是深思熟虑地设计一种方法，在有限的实地观测的情况下，对河流系统使用往往最少的监测网络。我们建议将重点放在鄂毕河上，这是流入北冰洋的四大河流之一。它在许多方面代表了北极的大型河流，但在某种程度上是独一无二的，这大大增加了它对本研究的实用性。鄂布盆地一直是前苏联大部分核武器生产和发展计划的所在地。由于这些设施的排放，在过去的50年里，各种示踪剂被引入到已知点源的河流系统中，这为研究污染物的转移速率和机制以及这一大型北极河流系统内的基本沉积物迁移和沉积提供了独特的机会。我们将使用一个带有泥沙-输运和地球化学相互作用子模型的二维水动力模型来在河流数据集之间进行内插。在统计学意义上，我们将评估颗粒和相关示踪剂的命运如何受到地球化学、水文学、河流形态的几何形状以及必须对河流几何形状、水流和泥沙运移物理过程作出反应的物理过程的影响。通过制定详细的岩心年表，将建立来自沉积物岩心的地球化学数据、历史水文数据和模型之间的联系。这一年表将被用来将沉积速率和沉积物特征在空间和时间上的变化与水文条件和模型预测的多年变化联系起来。最近从其与额尔齐斯河汇合处上方的Ob获得的数据有力地证实了在该流域进行研究的实用性。这条河的沉积物含有独特的同位素特征，可以有效地给它的沉积物贴上标签。一个同位素比240Pu/239Pu在过去50年中是恒定的，这为识别下游混合物中的这些沉积物提供了一个标签。第二种示踪剂237Np随时间变化很大，变化幅度高达一个数量级，提供了一个时变信号，用于估计传输和沉积速率。这种独特的签名是实现这里提出的目标的理想选择。这项建议已提交给EGB计划，并由以下各方共同资助：1.CTS(Arndt)和(Roco)部门2.INT-(Dudka)部门3.OPP部门-(LedBetter)4.OCE部门-(Buesseler)

9807590SaylesWe propose an interdisciplinary approach for the evaluation of the riverine transport of sediments and particle-associated contaminants that is applicable to many sparsely measured river-dominated coastal systems. To overcome data restrictions and cover large spatial scales, we propose the joint use of geochemical, hydrodynamic, and hydrological data sets together with high-resolution models of transport and geochemical processes. Our objective is to provide basic information on the pathways, dynamics, and controls on transport and depositional environments, and to explore the sensitivity of the system to contaminant- loading and accumulation. A very important aspect of the study is the deliberate design of the approach to use the often-minimal monitoring network on river systems together with limited field observations. We propose to focus our study on the Ob River, one of the four largest rivers flowing into the Arctic Ocean. It is representative of large Arctic rivers in many respects, but is unique in a way that adds greatly to its utility for the present study. The Ob basin has been the site of the bulk of the nuclear weapons production and development program of the former Soviet Union. As a result of releases from thee facilities, a variety of tracers has been introduced, over the past 50 years, into the river system at known point-sources providing unique opportunities for studying pollutant transfer rates and mechanism, as well as basic sediment transport and deposition within this large arctic river system. We will use a two-dimensional hydrodynamic model with sediment-transport and geochemical interaction submodels to interpolate between river data sets. In a statistical sense, we will evaluate how the fate of the particles and associated tracers is governed by the geochemistry, the hydrology, the geometry of the river configuration, and the physical processes that must be responsive to the river geometry, flow, and the physics of sediment transport. The links between the geochemical data derived from the sediment cores, the historical hydrologic data, and the models will be established through developing detailed chronologies for the cores. This chronology then would be used to relate changes in accumulation rates and sediment characteristics in space and in time to multiyear changes in hydrologic conditions and model predictions.Recently obtained data from Ob above its confluence with the Irtysh provide strong confirmation of the utility of studies in this river basin. The sediments from this river contain uniques isotopic signatures that effectively "tag" its sediments. One isotopic ratio, 240Pu/239Pu, is ~constant over the past 50 years providing a label to identify these sediments in mixtures down stream. A second tracer, 237Np, varies strongly over times, by up to an order of magnitude, providing a time varying signal for use in estimating transport and deposition rates. Such unique signatures are ideal for meeting the goals proposed here. This proposal was submitted to the EGB Program and is being jointly funded by:1. Division of CTS (Arndt) and (Roco)2. Division of INT - (Dudka)3. Division of OPP - (Ledbetter)4. Division of OCE - (Buesseler)