Collaborative Research: Parsing out the controls of climate, geology, and land use on riverine (234U/238U) ratios in Texas river basins

合作研究：解析气候、地质和土地利用对德克萨斯河流域河流 (234U/238U) 比率的控制

• 批准号: 1933259
• 负责人: Lin Ma
• 金额: $ 50.1万
• 依托单位: University of Texas at El Paso
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-15 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1933259&HistoricalAwards=false
• 关键词: Collaborative; Research; Parsing; out; controls

This proposal will investigate the variations of uranium isotope ratios (234U/238U), a naturally occurring and easy-to-detect geochemical signature, in large Texas rivers that flow from northwest to southeast across the state. This study aims to understand in detail how changes of climate parameters (such as rainfall and temperature), rock type (sandstone, shale, limestone, and evaporite) and land uses (agricultural, urban, and natural) in Texas river basins control the river (234U/238U) ratios. Knowing this important information will advance knowledge of 1) how fast natural rocks break down to form soils and release solutes and mineral nutrients into river basins; 2) how surface water interacts with groundwater flow and whether certain observed water quality issues are related to agricultural or urban water uses; and 3) how to interpret (234U/238U) ratios in geological records such as carbonates in soils, caves, and travertine deposits to reconstruct past environmental and hydrological conditions. The gained knowledge will advance the scientific fields of low temperature geochemistry, hydrology, paleoclimatology, and environmental science with important societal impacts especially related to water resources management. This study will support a team of 4 early to mid-career faculty, 3 graduate, and 8 undergraduate students from University of Texas at El Paso (a minority serving and Carnegie R1 university), Oregon State University/University of Kansas, and El Paso Community College (a large urban community college). This proposal will provide a valuable research and education opportunity for graduate and undergraduate students, and especially community college students from two geographically distinct regions (Southwest and Central USA) facing different but equally pressing water and environmental issues due to agriculture and urban development. Investigators will develop environmental science development programs (ESPD) with hands-on training both in the field and laboratory, online training modules, geohydrological field trips for the general public, and outreach events with the Kay Bailey Hutchison Desalination Plant and Earth Science day at El Paso. These experiences will allow students to develop necessary scientific research skills for their future career in Geoscience, Environmental Science, and Critical Zone Science.Riverine (234U/238U) ratios have great potential to advance the understanding of watershed functions, ecosystem services, water sustainability, surface and groundwater management, and global carbon and nutrient cycles. However, their widespread adoption for solving many critical geochemical and hydrological issues has been hindered by the inability to decipher the multitude of mechanisms that control (234U/238U) ratios across climate, lithology, and land use gradients. Here, researchers will test the umbrella hypothesis that riverine (234U/238U) ratios can be predicted by quantifying factors of alpha recoil and chemical dissolution at the weathering interfaces that are controlled by 1) climate parameters (precipitation and temperature) of the watershed; 2) lithological parameters of the weathering bedrock (e.g., grain size and mineral weatherability); and 3) water residence times; while land uses (agriculture and urban development) can overprint these natural signatures. Their approach is to leverage the strong environmental and geologic gradients across Texas river basins with sizes ranging from 10s-100s of km, at a critical regional scale that will fill the gap existing in current watershed studies. They will conduct a combined geochemical, geological, and geographic information system (GIS) study to investigate the controls of precipitation, lithology, and land uses on the riverine (234U/238U) ratios in Texas. They will also test (234U/238U) fractionation models in the existing literature across this matrix of drivers for the first time with the observed U isotope fractionation in these watersheds. The gained knowledge will be transferable outside of Texas as (234U/238U) fractionation is a ubiquitous signature observed in rivers, watersheds, and the geological record.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该提案将调查德克萨斯州从西北向东南流经该州的大河流中铀同位素比 (234U/238U) 的变化，这是一种自然发生且易于检测的地球化学特征。本研究旨在详细了解德克萨斯州河流流域的气候参数（如降雨量和温度）、岩石类型（砂岩、页岩、石灰岩和蒸发岩）和土地利用（农业、城市和自然）的变化如何控制河流(234U/238U) 比率。了解这些重要信息将增进以下方面的知识：1）天然岩石分解形成土壤并向河流流域释放溶质和矿质养分的速度有多快； 2) 地表水如何与地下水流相互作用，以及观察到的某些水质问题是否与农业或城市用水有关； 3）如何解释地质记录中的（234U/238U）比率，例如土壤、洞穴和石灰华沉积物中的碳酸盐，以重建过去的环境和水文条件。所获得的知识将推动低温地球化学、水文学、古气候学和环境科学等科学领域的发展，产生重要的社会影响，特别是与水资源管理相关的影响。这项研究将为德克萨斯大学埃尔帕索分校（一所少数族裔在职卡内基 R1 大学）、俄勒冈州立大学/堪萨斯大学和埃尔帕索的 4 名早期到中期职业教师、3 名研究生和 8 名本科生提供支持社区学院（大型城市社区学院）。该提案将为研究生和本科生，特别是来自两个地理不同地区（美国西南部和中部）的社区学院学生提供宝贵的研究和教育机会，这些学生因农业和城市发展而面临不同但同样紧迫的水和环境问题。研究人员将制定环境科学发展计划（ESPD），包括现场和实验室的实践培训、在线培训模块、面向公众的地质水文实地考察以及在埃尔凯贝利和记海水淡化厂和地球科学日举办的外展活动帕索。这些经验将使学生能够为他们未来在地球科学、环境科学和关键区域科学方面的职业发展必要的科学研究技能。河流 (234U/238U) 比率具有巨大的潜力，可以促进对流域功能、生态系统服务、水可持续性、地表水和地下水管理以及全球碳和养分循环。然而，由于无法破译控制气候、岩性和土地利用梯度的 (234U/238U) 比率的多种机制，它们在解决许多关键地球化学和水文问题上的广泛采用受到了阻碍。在这里，研究人员将测试伞形假设，即可以通过量化风化界面处的阿尔法反冲和化学溶解因素来预测河流（234U/238U）比率，这些因素受以下因素控制：1）流域的气候参数（降水和温度）； 2）风化基岩的岩性参数（如粒度、矿物耐候性）； 3) 水停留时间；而土地利用（农业和城市发展）可以印上这些自然特征。他们的方法是在关键区域尺度上利用德克萨斯州河流流域数十至数百公里的强大环境和地质梯度，这将填补当前流域研究中存在的空白。他们将进行综合地球化学、地质和地理信息系统 (GIS) 研究，以调查降水、岩性和土地利用对德克萨斯州河流 (234U/238U) 比率的控制。他们还将首次通过在这些流域中观察到的 U 同位素分馏来测试现有文献中跨该驱动因素矩阵的 (234U/238U) 分馏模型。所获得的知识将可转移到德克萨斯州以外的地区，因为 (234U/238U) 分馏是在河流、流域和地质记录中观察到的普遍特征。该奖项反映了 NSF 的法定使命，并通过使用基金会的知识进行评估，被认为值得支持。优点和更广泛的影响审查标准。

项目成果

Regional Drivers of Stream Chemical Behavior: Leveraging Lithology, Land Use, and Climate Gradients Across the Colorado River, Texas USA

河流化学行为的区域驱动因素：利用美国德克萨斯州科罗拉多河的岩性、土地利用和气候梯度

• DOI: 10.1029/2022wr032155
• 发表时间: 2022
• 期刊: Water Resources Research
• 影响因子: 5.4
• 作者: Goldrich‐Middaugh, G. M.;Ma, L.;Engle, M. A.;Ricketts, J. W.;Soto‐Montero, P.;Sullivan, P. L.
• 通讯作者: Sullivan, P. L.