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

无机碳通量中床荷和悬浮荷载作用的量化

• 批准号: 1141745
• 负责人: Carol Wicks
• 金额: $ 29.68万
• 依托单位: Louisiana State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1141745&HistoricalAwards=false
• 关键词: Quantification; role; bedload; suspended; load

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.

无机碳通量中推移质和悬移质作用的定量化Carol M Wicks，路易斯安那州立大学碳酸盐地形景观剥蚀的理论模型基于对化学过程的理解，并允许对岩溶系统中碳酸盐的化学侵蚀和大气二氧化碳的一个汇进行核算。这些现有的模型假设，机械去除碳酸盐在岩溶地形是可以忽略不计的。本研究将通过在现有地球化学模型中增加碳酸盐的机械去除来测试这一假设，并将允许更精确地核算与碳酸盐地区相关的大气CO2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，量化颗粒无机碳的悬浮物输运和通量，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，并允许计算总通量无机碳。为了表征悬浮负荷通量，将使用直接采样和悬浮负荷的计算，作为悬浮泥沙浓度和流速的乘积的深度积分。 因为它是知之甚少，本研究的一个主要努力将是描述和量化的推移质通量在岩溶管道确定泥沙输运关系的河流有界横截面。沉积物输运关系将与观察到的推移质运动以及地表河流中沉积物输运的现有模型进行比较。我们的预期成果是开发的喀斯特河流推移质输移关系，定量的颗粒无机碳通量作为推移质和悬移质，岩溶环境中碳酸盐溶解的研究清楚地表明，溶解过程作为全球碳的瞬时汇，循环由于二氧化碳的损失和碳酸氢盐的产生。 在中低流量条件下，化学过程明显主导碳酸盐的去除。 然而，在风暴事件期间，碳酸盐物质（推移质和悬移质）的颗粒和卵石的机械运动可以是无机碳通量的主要组成部分。 在每年的风暴事件周期中，这些粒子的运动可能占每年质量去除的很大比例。 这项研究将专门调查这些颗粒的运动，提高我们对碳循环和景观剥蚀的理解。此外，该项目通过LSU学生地质强化定向计划的研究经验整合了研究和教育，该计划旨在帮助即将入学的新生在第一个秋季学期开始之前过渡到大学水平课程工作的期望。地质学强化方向的学生将在密西西比河进行沉积物运输研究，并将介绍全球碳循环。