Joint Publication "Estimation of Capillary-Associated NAPL-Water Interfacial Areas for Unconsolidated Porous Media by Kinetic Interface Sensitive (KIS) Tracer Method"

New joint publication, published in "Water Resources Research". The work has been developed within SimTech, the DFG project 428614366 and the SFB 1313 research projects A02, C04 and Z02.

"Estimation of Capillary-Associated NAPL-Water Interfacial Areas for Unconsolidated Porous Media by Kinetic Interface Sensitive (KIS) Tracer Method"

Authors

• Alexandru Tatomir (Georg-August-Universität Göttingen)
• Huhao Gao (Georg-August-Universität Göttingen)
• Hiwa Abdullah (Georg-August-Universität Göttingen)
• Christopher Pötzl (Georg-August-Universität Göttingen) 
• Nikolaos Karadimitriou (University of Stuttgart, SFB 1313 research project Z02)
• Holger Steeb (University of Stuttgart, SFB 1313 research projects B05, C05, and Z02)
• Tobias Licha (Ruhr Universität Bochum)
• Holger Class (University of Stuttgart, SFB 1313 research project C04)
• Rainer Helmig (University of Stuttgart, SFB 1313 research projects A02 and C02)
• Martin Sauter (Georg-August-Universität Göttingen) 

Abstract

By employing kinetic interface sensitive (KIS) tracers, we investigate three different types of glass-bead materials and three natural porous media systems to quantitatively characterize the influence of the porous-medium grain-, pore-size and texture on the specific capillary-associated interfacial area (FIFA) between an organic liquid and water. By interpreting the breakthrough curves (BTCs) of the reaction product of the KIS tracer hydrolysis, we obtain a relation for the specific IFA and wetting phase saturation. The immiscible displacement process coupled with the reactive tracer transport across the fluid–fluid interface is simulated with a Darcy-scale numerical model. Linear relations between the specific capillary-associated FIFA and the inverse mean grain diameter can be established for measurements with glass beads and natural soils. We find that the grain size has minimal effect on the capillary-associated FIFA for unconsolidated porous media formed by glass beads. Conversely, for unconsolidated porous media formed by natural soils, the capillary-associated FIFA linearly increases with the inverse mean grain diameter, and it is much larger than that from glass beads. This indicates that the surface roughness and the irregular shape of the grains can cause the capillary-associated FIFA to increase. The results are also compared with the data collected from literature, measured with high resolution microtomography and partitioning tracer methods. Our study considerably expands the applicability range of the KIS tracers and enhances the confidence in the robustness of the method.