0000000000387605
AUTHOR
Johannes Kulenkampff
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…
Evaluation of positron-emission-tomography for visualisation of migration processes in geomaterials
Abstract Positron-emission-tomography (PET) was applied for direct visualisation of solute transport in order to overcome the limitations of conventional methods for measuring advection and diffusion properties. At intervals from minutes to days the 3D-spatial distribution of the PET-tracer is determined. This spatiotemporal evolution of the tracer concentration can be used as experimental basis for clarification of the relevant transport processes, derivation of transport parameters, and model calibration. Here, 18 F and 124 I in 0.01 M carrier solution of KF and KI, respectively, have been chosen out of the limited number of available PET-tracers, primarily on account of their decay time …