Tracing Water Flow and Colloidal Particles Transfer in an Unsaturated SoilReport as inadecuate

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In recentyears, many studies have been carried out on colloidal particle transfer in theunsaturated zone because they can be a risk to the environment either directly oras a vector of pollutants. A study was conducted on the influence of porous mediastructure in unsaturated conditions on colloidal particle transport. Three granularmaterials were set up in columns to replicate a fluvio-glacial soil from the unsaturatedzone in the Lyon area France. It is a sand, a bimodal mixture in equal proportionby weight of sand and gravel, and a fraction of bimodal mixture. Nanoparticles ofsilica SiO2-Au-FluoNPs, having a hydrodynamic diameter between 50 and60 nm, labeled by organic fluorescent molecules were used to simulate the transportof colloidal particles. A nonreactive tracer, bromide ion Br- at aconcentration of C0,s = 10-2 M was used to determine the hydrodispersive properties of porous media. The testswere carried out first, with a solution of nanoparticles C0,p = 0.2 g-L and secondly, with a solution of nanoparticlesand bromine. The transfer model based on fractionation of water into two phases,mobile and immobile, MIM, correctly fits the elution curves. The retention of colloidalparticles is greater in the two media of bimodal particle size than that in thesand, which clearly demonstrates the role of textural heterogeneity in the retentionmechanism. The increase in ionic strength produced by alimenting the columns withcolloidal particle suspension in the presence of bromide, increases retention upto 25% in the sand. The total concentration profile of nanoparticles collected atthe end of the experiment shows that the colloidal particles are retained primarilyat the entrance of the columns. Hydrodispersive calculated parameters indicate thatflow is more heterogeneous in bimodal media compared to sand.


Colloidal Particle Transport, Microstructure, Modeling, Unsaturated Soil

Cite this paper

Prédélus, D. , Lassabatere, L. , Coutinho, A. , Louis, C. , Brichart, T. , Slimène, E. , Winiarski, T. and Angulo-Jaramillo, R. 2014 Tracing Water Flow and Colloidal Particles Transfer in an Unsaturated Soil. Journal of Water Resource and Protection, 6, 696-709. doi: 10.4236-jwarp.2014.67067.

Author: Dieuseul Prédélus, Laurent Lassabatere, Artur Paiva Coutinho, Cédric Louis, Thomas Brichart2, Erij Ben Slimène, Thierry Winia



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