0000000000387601
AUTHOR
Madeleine Stoll
Effect of pH on the mobility of the herbicide MCPA in a sand-goethite column: 1D and 2D reactive transport modeling
Abstract Adsorption and transport of the herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) in a homogeneous sand-goethite system were investigated as a function of pH. Interaction of MCPA with the solid surface was geochemically modeled according to the charge distribution multisite complexation (CD-MUSIC) approach. Based on this calibration, retardation of MCPA transport in column experiments was significantly underestimated by conventional 1D simulations. As a new approach, Positron Emission Tomography (PET) was employed to analyze the flow field, using 18F− as a radiotracer. The observed heterogeneity was reproduced in 2D simulations assuming increased permeability and porosity at the…
Experimental and numerical investigations on the effect of fracture geometry and fracture aperture distribution on flow and solute transport in natural fractures.
The impact of fracture geometry and aperture distribution on fluid movement and on non-reactive solute transport was investigated experimentally and numerically in single fractures. For this purpose a hydrothermally altered and an unaltered granite drill core with axial fractures were investigated. Using three injection and three extraction locations at top and bottom of the fractured cores, different dipole flow fields were examined. The conservative tracer (Amino-G) breakthrough curves were measured using fluorescence spectroscopy. Based on 3-D digital data obtained by micro-computed tomography 2.5-D numerical models were generated for both fractures by mapping the measured aperture distr…