CAREER: Mass Transport in Groundwater: an Integration of Research and Experiential Education

可溶性污染物或示踪剂通过自然系统迁移，确定样品位置之间的浓度与时间曲线变化。通常，这些曲线显示出平流和弥散过程无法描述的长尾。无论我们是需要预测自然系统的进化还是供水的质量，我们都必须能够定量地预测这种尾矿行为。污染物迁移预测的可靠性取决于对原位流动和迁移过程的良好理解；然而，大的对比、复杂的连通性和极端的空间定位，加上稀疏的数据，限制了我们对控制现场尺度水文行为的基本过程和特性的理解。这项研究旨在帮助回答以下问题：在何种情况下，考虑到水力导电性的非均质性，通常使用的连续分散模型可以描述浓度历史的长尾迹，而不是需要在可移动和不可移动孔隙域之间进行局部扩散的双连续模型？双连续体传质已被用于解释某些环境中的复杂输运行为，但这一过程的实验验证存在问题，因为地球化学样品仅代表孔隙空间的可移动组分，因此不可能确定不移动域的过程。最近，PI及其同事已经证明，电地球物理技术提供了验证双连续体输运发生的手段，并通过采样总孔隙空间来估计控制这些过程的参数，而不仅仅是移动域。虽然这些结果显示了利用遥感数据直接估计控制传质的水文参数的希望？不动孔隙度和传质速率？在现场，确定双域系统何时控制传输是不清楚的。特别是，目前尚不清楚用这种方法可以实际研究什么尺度的传质速率（或扩散长度）和不动孔隙率，或者对输运的非均质性控制。本研究的目的是确定1)溶质是否在三个不同地质条件的野外活动带和不活动带之间局部扩散，以及2)非均质带内部和之间的传质过程如何影响我们对野外溶质运输的宏观看法。与此研究相关联的是开发一个综合水文地球物理学夏季课程，本科生研究人员将结合实地实验、课堂教学和数值模拟来开发和测试关于不同制度下控制运输过程的假设。这个野外营地将与三所hbcu（历史上的黑人学院和大学）合作，与宾夕法尼亚州立大学和暑期研究机会计划（SROP）合作，这是一个为期夏季的实习项目，吸引来自少数族裔和机构的学生在机构合作委员会的大多数机构进行前沿研究。

Soluble contaminants or tracers migrate through natural systems defining concentration versus time curves that vary between sample locations. Often, these curves show long tails that are not described by the processes of advection and dispersion. Whether we need to predict evolution of natural systems or the quality of our water supply, we must be able to quantitatively predict such tailing behavior. The reliability of contaminant transport predictions depends on a good understanding of in-situ flow and transport processes; however, large contrasts, complex connectivity, and extreme spatial localization of hydraulic properties combine with sparse data to limit our understanding of fundamental processes and properties controlling field-scale hydrologic behavior. This research looks to help answer the following question: Under what scenarios canlong tailing of concentration histories be described by commonly used advective-dispersive models given hydraulic conductivity heterogeneity, versus the need for bicontinuum models with local diffusion between mobile and less mobile porosity domains?Bicontinuum mass transfer has been used to explain complex transport behavior in some environments, but experimental verification of this process is problematic because geochemical samples only represent the mobile component of the pore space, making determination of processes in the immobile domain impossible. Recently, the PI and colleagues have demonstrated that electrical geophysical techniques provide ameans of verifying the occurrence of bicontinuum transport and estimating the parameters which control these processes by sampling the total pore space, rather than just the mobile domain. While these results show promise for using remotely sensed data for directly estimating hydrologic parameters controlling mass transfer?immobileporosity and mass-transfer rate?in situ, determining when dual-domain systems control transport is unclear. In particular, it is not clear what scales of mass transfer rates (or diffusion lengths) and immobile porosity fractions can be practically investigated with this approach, or heterogeneity controls on transport. The objectives of this research are to determine 1) whether solutes locally diffuse between mobile and less mobile zones at three field sites of differing geology, and 2) how mass transfer processes within and between heterogeneous zones affect our macroscopic view of solute transport in the field.Tied to this research is the development of an integrated hydrogeophysics summer course, where undergraduate researchers will combine field experimentation, in-class instruction, and numerical modeling to develop and test hypotheses regarding the processes controlling transport under different regimes. This field camp will be run in collaboration with three HBCUs (Historically Black Colleges and Universities) partnered with Penn State and the Summer Research Opportunity Program (SROP), a summer-long internship that engages students from minority groups and institutions in cutting-edgeresearch at majority institutions of the Committee on Institutional Cooperation.