%0 Conference Proceedings %F Poster %T Statistics of concentration gradients in porous media %+ Géosciences Rennes (GR) %+ Laboratoire de Physique de l'ENS Lyon (Phys-ENS) %+ Institute of Environmental Assessment and Water Research (IDAEA) %+ Institut de Recherche sur les Phénomènes Hors Equilibre (IRPHE) %A Le Borgne, Tanguy %A Schuck, Peter %A Dentz, Marco %A Villermaux, Emmanuel %< avec comité de lecture %B European Geosciences Union General Assembly 2017 %C Vienne, Austria %V 19 %P EGU2017-11100-2 %8 2017-04-23 %D 2017 %Z Sciences of the Universe [physics]/Earth Sciences/Hydrology %Z Sciences of the Universe [physics]/Earth Sciences/GeochemistryConference poster %X In subsurface environments, concentration gradients develop at interfaces between surface water and groundwaterbodies, such as hyporheic zones, saline wedges or recharge areas, as well as around contaminant plumes and fluidsinjected in subsurface operations. These areas generally represent hotspots of biogeochemical reactions, such asredox, dissolution and precipitation reactions, as concentration gradients create opportunities for reactive agentsto mix and generate chemical disequilibrium. While macrodispersion theories predict smooth gradients, decayingin time due to dispersive dissipation, we show that concentration gradients can be broadly distributed since theyare enhanced by velocity gradients induced by medium heterogeneity. We thus present a stochastic theory linkingthe Probability Density Function (PDF) of concentration gradients to flow heterogeneity (Le Borgne et al., 2017).Analytical predictions are validated from high resolution simulations of transport in heterogeneous Darcy fieldsranging from small to large permeability variances and low to high Peclet numbers. This modelling frameworkhence opens new perspectives for quantifying the dynamics of chemical gradient distributions and the kinetics ofassociated biogeochemical reactions in a stochastic framework.References:Le Borgne T., P.D. Huck, M. Dentz and E. Villermaux (2017) Scalar gradients in stirred mixtures and thedeconstruction of random fields, J. of Fluid Mech. 812, pp. 578–610. doi: 10.1017/jfm.2016.799 %G English %L insu-01534208 %U https://insu.hal.science/insu-01534208 %~ ENS-LYON %~ INSU %~ UNIV-RENNES1 %~ UR2-HB %~ CNRS %~ UNIV-AMU %~ UNIV-LYON1 %~ IRPHE %~ GR %~ EC-MARSEILLE %~ OSUR %~ GIP-BE %~ UR1-HAL %~ UR1-SDLM %~ GR-DIMENV %~ UNIV-RENNES2 %~ OSUR-OSU %~ TEST-UNIV-RENNES %~ TEST-UR-CSS %~ UNIV-RENNES %~ UDL %~ UNIV-LYON %~ INRAE %~ UR1-ENV %~ GR-TERA %~ TEST3-HALCNRS %~ TEST4-HALCNRS