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.

在流域水文学中，溶解硅浓度和浓度-流量关系已被广泛用作地下水流路径的示踪剂。 这项研究将采用Ge/Si比作为新型水文示踪剂，并将测试有关陆生植物在控制溪流Si通量中的作用的新想法。来自波多黎各（Rio Icacos）研究集水区的Ge/Si数据将通过氧同位素分析、水文数据和物理水文模型进行补充，以测试以下假设：A）在基流处的溪流中观察到的高Si浓度反映了腐泥土-基岩界面的风化。 这种硅通过深层地下水排放输送到溪流中; B）径流事件期间观察到的低硅浓度反映了硅从次生土壤矿物快速释放到沿沿着浅渗透性不连续流动的水中; C）高硅浓度有时存在于浅土壤孔隙水中反映了植物循环和植硅石溶解。 该硅不包括在我们的网站的整体溪流硅通量的显着部分。 该项目旨在开发一种新的工具，以增加我们对水的地下运动，水向溪流的输送以及控制溪流水化学过程的理解。 这些问题是水质的重要决定因素，是地球化学和水文学基础研究的核心。 在这里，我们应用这个工具（天然硅和微量元素锗的浓度在溪流）在波多黎各的加勒比国家森林的一个既定的研究流域。 该项目承诺整合来自水源的额外化学示踪剂以及土壤湿度和地下水位的物理测量的信息，并使用水流的数学模型。 从这项研究中收集的数据和提出的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这一工具奠定基础。