Contaminant Transport in Heterogeneous Soils from Different Land Management Practices
Abstract
The fate and transport of contaminants associated with agricultural soils have important implications for groundwater quality and public health. Intricacies of the pore structure control how water flow is distributed and consequently how dissolved chemicals are transported in the subsurface. We hypothesize that the structural heterogeneity generated by different agricultural land management practices will affect the transport behavior of agrochemicals in these soils. In particular, we expect that ploughed soils will exhibit more extreme anomalous transport, relative to no-till soils, due to the widening of pores during the deep churning process. We test this hypothesis with data from direct numerical simulations of tomographic images of soil samples obtained from a long-term agricultural field station in the United Kingdom. The velocity field in each soil domain is solved from the full Navier-Stokes equations and massless particle tracers are tracked accordingly. A statistical analysis of the Lagrangian tracks is presented to compare the velocity distribution, velocity correlation length, breakthrough curve, and evolution of displacement moments that characterize each land management practice. Finally, we upscale the pore-scale particle dynamics with a Continuous Time Random Walk modeling framework that accurately forecasts large-scale anomalous behavior. An improved understanding of the controls for contaminant transport in agricultural soils and of the predictive tools to model contaminant transport are key to helping decision makers implement more sustainable strategies in agriculture.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H25O1205D