Collaborative Research on Reactive Transport: Modeling Spatial Cross-Correlation between Hydraulic and Reactive Aquifer Attributes as Determined by Sedimentary Architecture

[538037]反应性输运协同研究：由沉积结构确定的水力和反应性含水层属性的空间相互关系建模反应性质量输运模型需要表征渗透率(k)和吸附分布系数（Kd）等水力和反应性属性在空间上的变化情况。目前还没有模型纳入这些属性的协变的真实特征，这些特征是在以前详细的实地研究中观察到的。这是反应性输运模型的一个重要限制。我们假设，沉积层中水力属性和反应属性之间的空间共变异性取决于单元类型之间的转换，就像之前对水力属性本身的空间变异性所显示的那样。该假说是基于这样一个概念，即沉积物侵蚀、运输和沉积包括自然地对沉积物颗粒进行分类并产生不同成分（矿物学）和粒度的单元类型的过程。我们的假设是基于对Borden含水层收集的岩相、k和Kd数据的观察和初步测试。该项目的具体目标是开发和探索一种新的模型，该模型代表了水力和反应属性的空间共变性，作为沉积矿床分层结构的函数，以及不同相关尺度的岩性单元内部和之间的过渡概率。该模型将表示在最近的实地研究中观察到的以下关系：(1)点相关性在某些单位类型中可能是正的，而在其他单位类型中可能是不相关或负的。(2)如果存在相关性，则不一定是完美的。(3)跨单位边界翻译的滞后互相关在跨某些单位类型转换时可能为正，在其他单位类型转换时可能为负。(4)沉积构造内不同尺度的单元类型可形成多个相关的整体对比尺度。这些活动将包括从一个特征良好的野外站点开发一个适当的数据集，计算模型中表示层次内和层次间关系的项，并了解这些项中哪些对复合尺度（即观察羽流扩散的尺度）的相互关系有重大贡献。一旦我们理解了哪些项是重要的，我们将对它们进行建模，作为开发复合模型函数的一部分。该项目将涉及两名具有地球化学和地质统计学专门知识的水文地质学家和一名沉积学家之间的合作。拟议活动的智力价值：解释性计算建模研究尚未能够同时再现在对照现场研究中观察到的非理想运输行为的所有方面。这强烈表明，反应性输运的基本方面尚未完全了解。我们在此假设，在解释反应性输运模型中，缺乏对水力和反应性属性之间的共变性的适当表示是此类研究中的一个重大限制。拟议的项目将加强对水力和反应属性的共变性的全面理解。它将帮助研究界超越目前用于表示共变性的简单范式，并导致根据实地观察建立的有充分根据的替代模型的发展。因此，我们提出的工作将通过改进我们在反应性输运模型中对水力和反应性属性的表示，对解释性反应性输运建模产生重要影响。拟议活动产生的更广泛影响：该项目的更广泛影响可分为两大类：通过直接或间接参与该项目加强学生培训的影响，以及通过提高对沉积含水层中有机污染物命运的了解而造福社会的影响

0538037RitziCollaborative Research on Reactive Transport:Modeling Spatial Cross-Correlation between Hydraulic and ReactiveAquifer Attributes as Determined by Sedimentary ArchitectureModels for reactive mass transport require a representation of how hydraulic and reactive attributes, such as permeability (k) and the sorption distribution coefficient (Kd), vary in space. No model has yet incorporated the authentic features of the co-variability of these attributesobserved in previous, detailed field studies. This is an important limitation of reactive transport models. We hypothesize that spatial co-variability between hydraulic and reactive attributes in sedimentary deposits depends upon transitions across unit types, much as has been previously shown for spatial variability of hydraulic attributes themselves. The hypothesis is predicated on the concept that sediment erosion, transport and deposition include processes which naturally sort sediment grains and create unit types that differ in composition (mineralogy) as well as grain size.Our hypothesis is based on observations and preliminary testing using lithofacies, k, and Kd data collected for the Borden aquifer. The specific goal of the proposed project is to develop and explore a new model that represents the spatial co-variability of hydraulic and reactive attributes as a function of the hierarchical architecture of sedimentary deposits and the probabilities for transitioning within and between lithologic units across different, relevant scales. The model will represent the following relationships observed in recent field studies: (1)The point-correlation may be positive within some unit types and uncorrelated or negative within others. (2) If correlation exists, it need not be perfect. (3) The lag cross-correlation with translation across unit boundaries may be positive when transitioning across certain unit types and negative across others. (4) There can be multiple, relevant integral scales of correlation associated with the different scale of unit types within the sedimentary architecture. The activities will include developing an appropriate data set from a well-characterized field site, computing theterms of the model which represent relationships within and across hierarchical levels, and gaining an understanding of which of these terms contribute significantly to the cross-correlation at the composite scale, which is the scale at which plume spreading is observed. Once we understand which terms are significant, we will model them as a part of developing the composite model function. The project will involve collaboration among two hydrogeologists, with expertise in geochemistry and geostatistics, and a sedimentologist. Intellectual merit of the proposed activity: Interpretive computational modeling studies have not yet been able to simultaneously reproduce all aspects of nonideal transport behavior that have been observed in controlled field studies. This strongly suggests that fundamental aspects of reactive transport are not yet fully understood. We posit here that lack of proper representation of the co-variability between hydraulic and reactive attributes within theinterpretive reactive transport models is a significant limitation within such studies. The proposed project will enhance overall understanding of co-variabilty of hydraulic and reactive attributes. It will help the research community to move beyond the simplistic paradigm currently used for representing co-variability and lead to development of a well-grounded alternative model built upfrom field observations. Thus, the work we propose will have an important impact on interpretive reactive transport modeling by improving our representation of the hydraulic and reactive attributes within reactive transport models.Broader impacts resulting from the proposed activity: The broader impacts of theproject fall within two general realms: those that enhance student training through direct or indirect participation in the project and those that benefit society through realization of improved understanding of the fate of organic contaminants within sedimentary aquifers