Collaborative Research: Controls on Delivery and Fate of Water, Nitrogen, and Calcium in a Spring-Fed Karst River

合作研究：泉水喀斯特河中水、氮和钙的输送和去向控制

• 批准号: 0838390
• 负责人: James Heffernan
• 金额: --
• 依托单位: Florida International University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-03-01 至 2013-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838390&HistoricalAwards=false
• 关键词: Collaborative; Research; Controls; Delivery; Fate

Intellectual Merit: Hydrologic, geomorphic and biogeochemical dynamics of river systems are coupled over time scales ranging from hours to millennia. Catchment inputs and flowpath properties influence geomorphic and biogeochemical processes through effects on water and solute delivery dynamics. Simultaneously, metabolic processes of river biota can exert reciprocal control on hydrology, morphology, and biogeochemistry. These coupled biotic-abiotic interactions lead to complex, non-linear responses that require high spatiotemporal density of data to understand. In spring-fed karst rivers, strong biotic-abiotic interactions are expected due to high plant production and low flow velocity, and are hypothesized to control both N and DO dynamics, with important ecosystem consequences, and also river water pH with implications for mineral dissolution and thus karst channel development. The magnitude of biotic controls on solute delivery, and links to stream channel dissolution, are poorly understood. Consequently, this proposal addresses 3 questions that link biotic and abiotic processing of spring-fed karst channels: 1) How do sub-surface flow paths vary with climate and flow regime, and how do they control the magnitude of spring water delivery, and the solute chemistry of the water? 2) What are the hydrologic and geomorphic controls on riverine N processing? 3) What are the biotic and hydrologic controls on channel dissolution in low-relief karst rivers?The study site is the Ichetucknee River in north Florida where multiple gauged springs merge to form an 8-km long river, which is also gauged 5 km downstream of the springs. The work plan includes: 1) continuous measurements of water chemistry, utilizing state-of-the-art sensors at strategically selected spring vent and river sites, 2) synoptic water sampling for analytes not continuously measured or at non-sensor sites, and 3) analysis of archival data at Ichetucknee and other regionally important springs to test hypotheses more generally. Continuously recording sensors, that measure DO concentrations, T, stage, specific conductivity, and pH, will be deployed at two springs, representing two hydrochemical groupings of the Ichetucknee complex. These, along with continuous NO3 and turbidity sensors, will also be deployed at three locations downstream. The continuously measured data will be used to assess delivery variability and in-stream processing of N (e.g. assimilatory uptake versus dissimilatory loss) at diel, episodic, seasonal, and inter-annual time scales. Monthly synoptic sampling will link the biological processes to carbonate saturation state and dissolution. Analyses of archival data from springs across the region, will allow statistical analyses (auto/cross-correlation) of discharge vs. chemistry relationships spanning a larger population of springs.Broader Impacts: Florida?s springs are significant regional cultural, economic, and ecological resources; observed ecological declines have made springs the subject of current regulatory consideration, with a focus on N pollution. As regulatory options are debated, poor mechanistic understanding of how springs process N limits the ability to make recommendations for how to manage them. Multiple local and state regulatory agencies and stakeholder groups (e.g., Ichetucknee Springs Basin Working Group, Florida Department of Environmental Protection, Florida Springs Task Force) allow translation of scientific knowledge into policy and public education. Results from this proposed work will be presented regularly to stakeholders at public and agency meetings. A significant portion of the research will be conducted at a minority serving institution (Florida International University); under-represented groups will be recruited to work as students and post-doctoral candidates. Co-locating this work with a WATERS test-bed location will expand the expertise gained about sensor networks and data infrastructure during the preliminary studies. This work will provide additional technological advances toward building sensing platforms, allowing critical information about river systems to be collected across process and management relevant time-scales.

智力优势：河流系统的水文、地貌和生物地球化学动力学在从几小时到几千年的时间尺度上是耦合的。流域输入和流路特性通过影响水和溶质输送动力学来影响地貌和生物地球化学过程。同时，河流生物群的代谢过程可以对水文、形态和生物地球化学产生相互控制。这些耦合的生物-非生物相互作用会导致复杂的非线性反应，需要高时空密度的数据才能理解。在泉水灌溉的喀斯特河流中，由于高植物产量和低流速，预计会产生强烈的生物-非生物相互作用，并假设控制氮和溶解氧动态，产生重要的生态系统后果，以及河水 pH 值对矿物质溶解的影响从而喀斯特河道的发育。人们对生物控制溶质输送的程度以及与水流通道溶解的联系知之甚少。因此，该提案解决了将泉水喀斯特水道的生物和非生物过程联系起来的 3 个问题：1) 地下水流路径如何随气候和水流状况变化，以及它们如何控制泉水输送的大小，以及水的溶质化学？ 2）河流氮处理的水文和地貌控制因素有哪些？ 3) 低地势喀斯特河流中河道溶解的生物和水文控制因素是什么？研究地点是佛罗里达州北部的伊切塔克尼河，那里多个测量泉水合并形成一条 8 公里长的河流，在下游 5 公里处也测量了这条河的泉水。工作计划包括：1) 在战略选择的泉水口和河流地点利用最先进的传感器对水化学进行连续测量，2) 对未连续测量或在非传感器地点的分析物进行天气水采样，以及 3 ）对伊切塔克尼和其他地区重要泉水的档案数据进行分析，以更广泛地检验假设。连续记录传感器可测量 DO 浓度、T、阶段、比电导率和 pH 值，将部署在两个泉水处，代表 Ichetucknee 综合体的两个水化学分组。这些传感器连同连续的 NO3 和浊度传感器也将部署在下游的三个位置。连续测量的数据将用于评估昼夜、偶发、季节和年际时间尺度的氮输送变异性和流内处理（例如同化吸收与异化损失）。每月天气采样将生物过程与碳酸盐饱和状态和溶解联系起来。对整个地区泉水的档案数据进行分析，可以对更多泉水的排放与化学关系进行统计分析（自动/互相关）。更广泛的影响：佛罗里达州的泉水具有重要的区域文化、经济和生态作用资源;观察到的生态衰退使泉水成为当前监管考虑的主题，重点是氮污染。随着监管选项的争论，对弹簧如何处理氮的机制了解不足限制了就如何管理它们提出建议的能力。多个地方和州监管机构和利益相关者团体（例如，Ichetucknee Springs Basin 工作组、佛罗里达州环境保护部、Florida Springs 特别工作组）允许将科学知识转化为政策和公共教育。这项拟议工作的结果将定期在公共和机构会议上向利益相关者介绍。很大一部分研究将在少数族裔服务机构（佛罗里达国际大学）进行；代表性不足的群体将被招募为学生和博士后候选人。将这项工作与 WATERS 测试台地点放在同一地点将扩大在初步研究期间获得的有关传感器网络和数据基础设施的专业知识。这项工作将为构建传感平台提供额外的技术进步，从而允许跨流程和管理相关时间尺度收集有关河流系统的关键信息。