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

地球的关键地带从基岩一直延伸到树梢。对于城市地区来说，建筑环境是关键地带不可分割但尚未得到充分研究的一部分。土壤和岩石影响地下水的化学成分，这些地下水从地下流向溪流。岩石的“天气”（化学变化）在很长一段时间内自下而上，影响地下水和溪流的化学。河流化学对淡水栖息地和饮用水质量至关重要。在城市地区，人类活动改变了这种地质基础，搬运建筑用土，埋水和下水管道，给道路施用盐和肥料。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，我们所知甚少。该项目研究了自然和人为风化过程的相互作用及其对水质的影响，并以费城、巴尔的摩、华盛顿特区和罗利四个城市为实验室。这些城市位于瀑布区，这是一个沿东海岸形成瀑布的地质转变。这些城市反映了气候、发展年龄和人口密度的变化。研究方法包括观测和模拟活动，整合了城市关键地带的多个过程。本项目每年培养本科生7人，研究生7人，博士后1人。项目参与者将与K-12教师合作，将关键区域科学融入课堂，并提供专业发展。将成立一个区域关键区域公民科学兴趣小组，在当地项目中采用项目协议，并为项目研究做出贡献。促进与其他关键区域科学家的广泛社区互动的参与计划包括举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关键区域过程纳入水质管理和有弹性、可持续的城市发展。该项目将通过横跨美国东海岸四个城市（费城、巴尔的摩、华盛顿特区和罗利）的关键区域（CZ）集群，推进对城市关键区域过程的了解。这些城市都是沿着瀑布带发展起来的，这是一个陡峭的河流切入大西洋沿岸平原上游的结晶山前基岩的地区。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老而密集的发展到罗利的新而稀疏的发展。该项目将解决以下研究问题：(1)温带东部沿海地区的城市化如何导致从供应限制到运输限制的绝对出口制度转变？(2)山前—滨海平原转型的CZ底层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沿纬度梯度的物质输出？研究方法将包括开发流域尺度地球化学-水文模型，作为数据收集、同化和预测的框架；地下制图的地球物理学；土地覆盖/土地利用数据分析；土壤岩心化学分析；土壤气体采样；溶质的溪流和井取样；以及沉积物浓度和产量的分析。一个新的概念模型的溶质运动从陆地表面通过地下到溪流，约束地质和地貌建筑和城市发展的套印。本项目每年培养本科生7人，研究生7人，博士后1人。现有的机构项目将被用来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，为CZ教学模块和教师专业发展计划确定主题。将成立一个区域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。项目参与计划包括举办公开的季度科学会议和建立访问学者基金，以支持与其他CZ集群站点的科学交流。该项目由关键区域协作网络和地球科学部的水文科学项目以及化学、生物工程、环境和运输系统部的环境可持续性项目共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.