Abstract
Abstract. Our study investigates interplays between dissolution, precipitation, and transport processes taking place across randomly heterogeneous conductivity domains and the ensuing spatial distribution of preferential pathways. We do so by relying on a collection of computational analyses of reactive transport performed in two-dimensional systems where the (natural) logarithm of conductivity is characterized by various degrees of spatial heterogeneity. Our results document that precipitation and dissolution jointly take place in the system, with the latter mainly occurring along preferential flow paths associated with the conductivity field and the former being observed at locations close to and clearly separated from these. High conductivity values associated with the preferential flow paths tend to further increase in time, giving rise to a self-sustained feedback between transport and reaction processes. The clear separation between regions where dissolution or precipitation takes place is imprinted onto the sample distributions of conductivity which tend to become visibly left skewed with time (with the appearance of a bimodal behavior at some times). The link between conductivity changes and reaction-driven processes promotes the emergence of non-Fickian effective transport features. The latter can be captured through a continuous-time random-walk model where solute travel times are approximated with a truncated power law probability distribution. The parameters of such a model shift towards values associated with increasingly high non-Fickian effective transport behavior as time progresses.
Highlights
Diagnosis and characterization of the feedback between geochemical precipitation/dissolution reactions and solute transport processes in heterogeneous subsurface systems is key to a variety of environmental and Earth science scenarios (Rege and Fogler, 1989; Berkowitz et al, 2016)
The latter distributions tend to be shifted towards high conductivity values and are characterized by an enhanced mean conductivity value as compared against their generated counterparts. This shift is imprinted onto the probability density function (PDF) of the waiting times and onto its associated TPL parameters, consistent with prior studies (Edery et al, 2014, 2016b; Edery, 2021)
We simulate reactive transport across the collection of generated fields, allowing for precipitation of calcite and assessing the evolution of the conductivity field according to the Kozeny–Carman formulation introduced in Sect
Summary
Diagnosis and characterization of the feedback between geochemical precipitation/dissolution reactions and solute transport processes in heterogeneous subsurface systems is key to a variety of environmental and Earth science scenarios (Rege and Fogler, 1989; Berkowitz et al, 2016). A critical challenge is the emergence of complex dependencies between physical and chemical processes taking place across aquifer bodies (Saripalli et al, 2001). Heterogeneity of these systems promotes diverse patterns of precipitation and/or dissolution that may imprint a variety of dynamic system responses, including, for example, wormhole and oscillatory behaviors of system attributes such as porosity and permeability (Edery et al, 2011; Garing et al, 2015; Golfier et al, 2002).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
