The Geochemical Carbon Cycle: A Vadose-Hydrologic Study of the Effect of Plants on Weathering

地球化学碳循环：植物对风化影响的渗流水文研究

• 批准号: 9508003
• 负责人: C. Kent Keller
• 金额: --
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-01-01 至 1996-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9508003&HistoricalAwards=false
• 关键词: Geochemical; Carbon; Cycle; Vadose; Hydrologic

9508003 Keller Carbon dioxide (CO2) is a greenhouse gas. One avenue to understanding the relationship of atmospheric CO2 concentration to climate, is to study processes affecting atmospheric CO2 on long time scales. The principal pathway for long-term transfer of CO2 from Earth's atmosphere to its crust is "chemical weathering" of common minerals in soils, subsoils, and groundwater systems followed by transport of the dissolved material to the oceans in continental drainage, where they are deposited on ocean floor. This sequence effects transfer of CO2 because mineral dissolution consumes CO2 containing acids, entrains bicarbonate, deposits carbonate minerals. CO2 in buried carbonate minerals returned to the atmosphere by volcanism and metamorphism. The relative rates of these processes determine the masses of CO2 in the atmosphere and lithosphere at any on time and, in the process, affect Earth's climate. It is therefore important the factors controlling the rates of the various processes in the cycle. Plant communities, are an important factor. Plants could enhance chemical weathering by raising subsurface concentrations of acids, facilitating the exposure of fresh mineral surfaces, and binding mineral grains into water-retaining structures characteristic of soils. The actual extent of weathering enhancement by these mechanisms is, however poorly understood because of the difficulty of factoring other variables out of comparative field studies. This study takes advantage of ongoing long-term, field-scale experiments in plant nutrient cycling. To collect needed data for subsequent research to test hypotheses on plant-weathering relationships. Existing instrumentation will is augmented to observe how chemical weathering evolves with depth and time in soils and subsoils beneath various plant communities

9508003凯勒二氧化碳(二氧化碳)是一种温室气体。要了解大气二氧化碳浓度与气候的关系，一个途径是研究在长时间尺度上影响大气二氧化碳的过程。二氧化碳从地球大气层向地壳的长期转移的主要途径是土壤、下层土壤和地下水系统中常见矿物质的“化学风化”，然后通过大陆排水将溶解的物质输送到海洋，在那里它们被沉积在海底。这一顺序影响二氧化碳的转移，因为矿物溶解消耗含有酸的二氧化碳，夹带重碳酸盐，沉积碳酸盐矿物。埋藏的碳酸盐矿物中的二氧化碳通过火山作用和变质作用返回大气。这些过程的相对速率决定了大气层和岩石圈中任何时候的二氧化碳质量，并在这个过程中影响地球气候。因此，重要的是控制周期中各种进程的速度的因素。植物群落，是一个重要因素。植物可以通过增加地下酸的浓度，促进新鲜矿物表面的暴露，以及将矿物颗粒结合到土壤特有的保水结构中，来加强化学风化。然而，由于很难从比较实地研究中提取其他变量，这些机制对风化增强的实际程度却知之甚少。这项研究利用了正在进行的长期的、田间规模的植物养分循环实验。为随后的研究收集必要的数据，以检验植物风化关系的假说。将增加现有的仪器，以观察不同植物群落下土壤和底土中的化学风化如何随着深度和时间的变化而演变。