Collaborative Research: Network Cluster: Urban Critical Zone processes along the Piedmont-Coastal Plain transition

地球的临界区横跨基岩到树梢。对于城市地区来说，建成环境是临界区中不可或缺但研究不足的一部分。土壤和岩石会影响地下水通过地下流向溪流的化学成分。岩石在很长一段时间内自下而上发生化学变化，影响地下水和溪流化学。溪流化学对淡水栖息地和饮用水质量至关重要。在城市地区，人类活动改变了这一地质基础，为了建设而搬运泥土，埋水和下水道，以及施道路盐和肥料。关于地上的城市过程和地下的地质过程如何相互作用来改变地下水和溪流的风化和化学作用，人们知之甚少。该项目研究自然和人为风化过程的相互作用及其对水质的影响，使用四个城市群作为我们的实验室-费城、巴尔的摩、华盛顿特区和罗利。这些城市位于秋季地带，这是一种地质过渡，沿着东海岸形成了瀑布。这些城市捕捉到了气候、发展年龄和人口密度的差异。研究方法包括观察和建模活动，将城市临界区的多种过程整合在一起。该项目每年将培养7名本科生、7名研究生和1名博士后。项目参与者将与K-12教师合作，将关键区域科学整合到课堂中，并提供专业发展。将召集一个区域关键区域公民科学兴趣小组，在当地计划中采用项目协议，并为项目研究做出贡献。促进与其他关键地带科学家的广泛社区互动的参与计划包括主办公开的季度科学会议和建立访问学者基金。项目成果将使政策制定者和监管机构能够将临界区进程纳入水质管理和弹性、可持续的城市发展。该项目将通过覆盖美国东海岸四个城市的临界区(CZ)集群，促进对城市临界区流程的了解。这些城市是沿着秋季地带发展起来的，这是一个陡峭的河流地区，切割成大西洋海岸平原上游的水晶山前基岩。这个城市群的南北梯度与气候趋势和年龄梯度有关，从费城和巴尔的摩的较老和密集的发展到罗利较新和较稀疏的发展。该项目将解决以下研究问题：(1)东部沿海温带景观中的城市化如何导致从供应受限到运输受限的溶质出口管理制度的转变？(2)沿山前-海岸平原过渡的CZ的基本结构如何与城市化相互作用，影响出口通量？(3)与城市化相关的化学和水文动力学如何影响从费城到罗利的纬度梯度上的材料出口？研究方法将包括开发流域尺度的地球化学-水文模型，作为数据收集、同化和预测的框架；用于地下测绘的地球物理；土地覆盖/土地利用数据分析；土壤和岩石岩心化学分析；土壤气体采样；河流和水井采样溶质；以及沉积物浓度和产量分析。将开发一个新的概念模型，即受地质和地貌建筑以及城市发展叠印的约束，溶质从地表通过地下到溪流的运动。该项目每年将培养7名本科生、7名研究生和1名博士后。将利用现有的机构方案，为该项目招募代表性不足的群体进入STEM领域。项目参与者将与高中科学教师合作，确定CZ教学模块和教师专业发展计划的主题。将召集一个地区性的CZ公民科学兴趣小组，以确定在当地计划中采用CZ项目协议的机会，并为CZ项目研究做出贡献。项目参与计划包括主持公开的季度科学会议和建立访问学者基金，以支持与CZ其他集群站点的科学交流。该项目由关键区域合作网络和地球科学部的水文科学项目以及化学、生物工程、环境和运输系统部门的环境可持续项目共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Earth’s Critical Zone spans bedrock to treetops. For urban areas, the built environment is an integral but understudied part of the Critical Zone. Soil and rock influence the chemistry of groundwater flowing through the subsurface to streams. Rocks “weather” (chemically change) from the bottom up over long periods, influencing groundwater and stream chemistry. Stream chemistry is critical for freshwater habitat and drinking water quality. In urban areas, human activities alter this geologic foundation, moving earth for construction, burying water and sewer pipes, and applying road salt and fertilizer. Little is known about how above-ground urban processes and below-ground geological processes interact to change weathering and chemistry of groundwater and streams. This project studies the interactions of natural and anthropogenic weathering processes and their effects on water quality, using a cluster of four cities as our laboratory -- Philadelphia, Baltimore, Washington, DC, and Raleigh. The cities are located along the Fall Zone - a geologic transition that creates waterfalls, along the Eastern Seaboard. The cities capture variation in climate, development age, and population density. Research methods include observational and modeling activities that integrated multiple processes in urban Critical Zones. This project will train 7 undergraduates per year, 7 graduate students, and 1 post-doctoral associate. Project participants will work with K-12 teachers to integrate Critical Zone science in the classroom and provide professional development. A regional Critical Zone Citizen Science Interest Group will be convened to adopt project protocols in local programs and contribute to project research. An engagement plan to foster interaction with a broad community of other Critical Zone scientists includes hosting open quarterly science meetings and establishing a visiting scholar fund. Project results will allow policy makers and regulators to incorporate Critical Zone processes into management of water quality and resilient, sustainable, urban development. This project will advance knowledge of urban critical zone processes through a Critical Zone (CZ) Cluster spanning four cities on the U.S. East Coast: Philadelphia, Baltimore, Washington, DC, and Raleigh. These cities were developed along the Fall Zone, a region of steep rivers incised into crystalline Piedmont bedrock upstream of the Atlantic Coastal Plain. The north-south gradient of this urban cluster is associated with climatic trends and with a gradient in age from older and denser development in Philadelphia and Baltimore to newer and sparser development in Raleigh. The project will address the following research questions: (1) How does urbanization in a temperate, Eastern seaboard landscape result in a shift from a supply-limited to a transport-limited regime governing solute export?; (2) How does the underlying structure of the CZ along the Piedmont-Coastal Plain transition interact with urbanization to affect export fluxes?; and (3) How do chemical and hydrological dynamics associated with urbanization affect material export along the latitudinal gradient from Philadelphia to Raleigh? Research methods will include development of a watershed-scale geochemical-hydrological model as a framework for data collection, assimilation, and prediction; geophysics for subsurface mapping; land cover/land use data analysis; soil and rock core chemical analysis; soil gas sampling; stream and well sampling for solutes; and analysis of sediment concentrations and yields. A new conceptual model of solute movement from the land surface through the subsurface to streams, constrained by geologic and geomorphic architecture and the overprinting of urban development will be developed. This project will train 7 undergraduates per year, 7 graduate students, and 1 post-doctoral associate. Existing institutional programs will be utilized to recruit underrepresented groups into STEM fields for the project. Project participants will work with high school science teachers to identify topics for a CZ instructional module and a teacher professional development program. A regional CZ Citizen Science Interest Group will be convened to identify opportunities to adopt CZ project protocols in local programs and to contribute to CZ project research. The project engagement plan includes hosting open quarterly science meetings and establishing a visiting scholar fund to support scientific exchange with other CZ cluster sites.This project is jointly funded by the Critical Zone Collaborative Network and the Hydrologic Sciences programs in the Division of Earth Sciences and the Environmental Sustainability program in the Division of Chemical, Bioengineering, Environmental and Transport Systems.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.