Silica Sources and Water Flowpaths in a Tropical Watershed: A Combined Ge/Si, Oxygen Isotope, and Hydrometric Study

热带流域的二氧化硅来源和水流路径：Ge/Si、氧同位素和水文测量的综合研究

• 批准号: 0538127
• 负责人: Andrew Kurtz
• 金额: $ 16.13万
• 依托单位: Trustees of Boston University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0538127&HistoricalAwards=false
• 关键词: Silica; Sources; Water; Flowpaths; Tropical

Dissolved silicon concentrations and silicon concentration-discharge relationships have been used widely as a tracer of subsurface flowpaths in catchment hydrology. This study will employ Ge/Si ratios as a novel hydrologic tracer, and will test emerging ideas regarding the role of terrestrial plants in controlling streamwater Si fluxes. Ge/Si data from a research catchment in Puerto Rico (Rio Icacos) will be supplemented by oxygen isotope analyses, hydrometric data, and physical hydrologic modeling to test the following hypotheses: A) High Si concentrations observed in streams at base flow reflect weathering at the saprolite-bedrock interface. This silicon is delivered to streams via deep groundwater discharge; B) Low Si concentrations observed during runoff events reflect rapid release of silicon from secondary soil minerals to water flowing along shallow permeability discontinuities; C) High Si concentrations sometimes present in shallow soil porewater reflect plant cycling and dissolution of phytoliths. This Si does not comprise a significant part of the overall streamwater Si flux at our site. This project is aimed at developing a new tool that will increase our understanding of the underground movement of water, delivery of water to streams, and the processes that control the chemistry of stream water. These issues are important determinants of water quality and are central to basic research in geochemistry and hydrology. Here we apply this tool (concentrations of naturally-occurring silicon and the trace element germanium in stream water) to an established research watershed in the Caribbean National Forest in Puerto Rico. The project promises to integrate information from additional chemical tracers of water sources plus physical measurements of soil moisture and water table levels, and use mathematical models of water flow. Data collected and ideas developed from this study should lay the groundwork for widespread application of this tool by hydrologists and geochemists in other settings.

溶解的硅浓度和硅浓度 - 释放关系已被广泛用作流域水文学中地下流道的示踪剂。 这项研究将采用GE/SI比率作为一种新型的水文示踪剂，并将测试有关陆地植物在控制流水中助体中的作用的新兴想法。来自波多黎各研究集水区（Rio icacos）的GE/SI数据将通过氧同位素分析，水文测定数据和物理水文建模来补充，以测试以下假设：a）a）在saprolite-bedrock Interface的流中观察到的高Si浓度。 该硅通过深地下水排放传递到溪流。 b）在径流事件期间观察到的低Si浓度反映了硅从二次土壤矿物质到沿浅渗透性不连续性流动的水的迅速释放。 c）有时在浅土壤孔隙水中存在的高Si浓度反映了植物循环和植物溶解。 该SI不包含我们网站上整个流水SI通量的重要组成部分。 该项目旨在开发一种新工具，以增强我们对水的地下运动，水向溪流的流动以及控制溪流化学的过程的理解。 这些问题是水质的重要决定因素，并且是地球化学和水文学基础研究的核心。 在这里，我们将此工具（在溪流水中的天然硅和痕量元素的浓度）应用于波多黎各加勒比国家森林的既定研究。 该项目有望从水源的其他化学示踪剂以及土壤水分和地下水位水平的物理测量中整合信息，并使用水流的数学模型。 从本研究中收集的数据和想法应该为水文学家和地球化学家在其他环境中广泛应用该工具的基础。