Quantification of the role of bedload and suspended load in the flux of inorganic carbon

泥沙和悬移质在无机碳通量中作用的量化路易斯安那州立大学Carol M Wicks碳酸盐地形地貌剥蚀的理论模型建立在对化学过程的理解基础上，并允许计算岩溶系统中碳酸盐的化学侵蚀和大气二氧化碳的一个汇。这些现有的模型假定岩溶地区碳酸盐的机械去除可以忽略不计。这项研究将通过将碳酸盐的机械去除添加到现有的地球化学模型中来检验这一假设，并将允许更准确地计算与碳酸盐地区相关的大气二氧化碳汇。该项目有三个主要目标：量化颗粒无机碳的推移质输运和通量，量化悬浮沙输运和颗粒无机碳的通量，以及量化溶解无机碳的通量，以与颗粒无机碳的通量进行比较，并能够计算总的无机碳通量。为了表征悬移质通量，采用悬沙浓度与流速乘积的深度积分直接采样和计算悬移质。由于了解甚少，这项研究的主要工作将是通过确定有界断面河流的泥沙输移关系来描述和量化岩溶管道中的推移质通量。泥沙输送关系将与观测到的推移质运动和现有的地表河流泥沙输送模型进行比较。我们的预期成果是发展岩溶河流推移质输运的关系，量化颗粒无机碳作为推移质和悬移质的通量，以及更好地了解通过物理过程从碳酸盐地形中去除的碳酸盐物质的比例。岩溶环境中碳酸盐溶解的研究清楚地证明了溶解过程作为全球碳循环中的瞬时汇的重要性，因为二氧化碳的损失和重碳酸盐的生成。在低到中等流动条件下，化学过程显然主导着碳酸盐的去除。然而，在风暴期间，碳酸盐物质的颗粒和鹅卵石(推移质和悬移质)的机械运动可能是无机碳通量的主要组成部分。在风暴事件的年度周期中，这些粒子的运动可能占每年质量移除量的很大比例。这项研究将专门研究这些颗粒的运动，并提高我们对碳循环和景观剥蚀的理解。此外，该项目通过路易斯安那州立大学地质学精修课程的研究经验将研究和教育结合在一起，该项目旨在帮助新生在第一个秋季学期开始之前过渡到大学水平的课程工作期望。地质学精修方向的学生将在密西西比河进行泥沙运移研究，并将介绍全球碳循环。

Quantification of the role of bedload and suspended load in the flux of inorganic carbonCarol M Wicks, Louisiana State UniversityTheoretical models of landscape denudation in carbonate terrains are based on an understanding of chemical processes and have allowed an accounting of chemical erosion of carbonate in karst systems and of one sink for atmospheric carbon dioxide. These existing models assume that the mechanical removal of carbonate in karst terrain is negligible. This study will test that assumption by adding mechanical removal of carbonate to the existing geochemical models and will allow more precise accounting of atmospheric CO2 sinks associated with carbonate regions. There are three primary objectives to the project: quantify bed load transport and flux of particulate inorganic carbon, quantify suspended load transport and flux of particulate inorganic carbon, and quantify the flux of dissolved inorganic carbon to compare to the flux of particulate inorganic carbon and to allow calculation of the total flux inorganic carbon. To characterize suspended load flux, direct sampling and computation of the suspended load as the depth-integration of the product of the suspended sediment concentration and the flow velocity will be used. Because it is poorly understood, a major effort of this research will be to describe and quantify bed load flux in karst conduits by determining sediment transport relations for streams with bounded cross sections. The sediment transport relations will be compared to observed bed load movement and to existing models of sediment transport in surface streams. Our expected outcomes are developed relations of bed load transport in karst streams, quantification of the flux of particulate inorganic carbon as bed load and as suspended load, and a better understanding of proportion of carbonate material that is removed from carbonate terrains via physical processes.Studies of carbonate dissolution in karst settings have clearly demonstrated the significance of the dissolution process as a transient sink in the global carbon cycle due to the loss of carbon dioxide and the creation of bicarbonate. Chemical processes clearly dominate removal of carbonate during low to moderate flow conditions. However, during storm events, the mechanical movement of particles and cobbles of carbonate material (bed load and suspended load) can be a major component of flux of inorganic carbon. Over an annual cycle of storm events, the movement of these particles may account for a large percentage of the annual removal of mass. This study will specifically investigate movement of these particles and improve our understanding of the carbon cycle and of landscape denudation. In addition, this project integrates research and education through the research experience of the Geology Intensive Orientation for Students program at LSU, a program designed to help the incoming Freshmen make the transition to the expectations of college-level course work prior to the start of their first fall semester. The students in the Geology Intensive Orientation for Students will conduct a sediment transport study in the Mississippi River and will be introduction to global carbon cycle.