GAS-REACT: GAS interchange and REACTive processes in coupled subsurface/atmosphere systems

• Applicants: Professor Dr.-Ing. Holger Class, since 1/2024; Professor Massimo Rolle, Ph.D.
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 529041613

The exchange of gases between the atmosphere and the subsurface is of crucial importance for biogeochemical cycles, contaminant dynamics, and groundwater quality in general. Such interchange phenomena at the atmosphere/subsurface interface and their influence on biogeochemical processes are strongly controlled by dynamic forcing (i.e., heat and wind flow) in the atmospheric compartment. Therefore, in order to gain a proper understanding of groundwater quality, particularly under on-going and projected climate change and global warming conditions, the coupling effects between the dynamics of atmospheric forcing and subsurface flow and reactive transport phenomena need to be investigated. The main goal of the proposed research is to mechanistically understand the impacts of atmospheric forcing on the interchange of gas components across the subsurface/atmosphere interface, on their migration behavior in the subsurface, and on their chemical reactions with reactive minerals controlling the composition and quality of the pore water. We focus on the interchange and transport of multicomponent gas mixtures containing oxygen, carbon dioxide and water vapor in coupled porous medium/free-flow domains and analyze the impact of their transport behavior on the extent of mineral reactions in the subsurface. Specific objectives include: (i) the investigation of atmospheric heat forcing on the interchange of multicomponent gas mixtures and its impact on geochemical reactions, (ii) the quantification of the effects of wind flow and soil surface roughness on gas exchange and reactive transport porous media, and (iii) the elucidation of the role of physical and chemical subsurface heterogeneity on evaporation-induced phase displacement in the porous medium and on the extent and rate of mineral reactions. The proposed approach is based on the combination of well-controlled, multi-dimensional, high-resolution laboratory experiments with advanced, process-based numerical modeling to explore and quantify the complex interactions between physical and geochemical processes in coupled atmosphere/subsurface systems. The outcomes of this project will be important for different environmental systems, greatly affected by rapidly changing atmospheric forcing due to climate change, including soil salinization, weathering of reactive minerals and geogenic contaminant release, greenhouse gases emissions from soils, and fate and transport of volatile pollutants.

• DFG Programme: Research Grants
• International Connection: Switzerland
• Co-Investigators: Professor Dr.-Ing. Rainer Helmig; Dr.-Ing. Martin Schneider
• Cooperation Partners: Dr. Joaquin Jimenez-Martinez; Dr. Klaus Mosthaf
• Ehemalige Antragstellerin: Dr.-Ing. Katharina Heck, until 12/2023