Technical Note: Mesocosm approach to quantify dissolved inorganic carbon percolation fluxes
- 1Department of Chemical and Biochemical Engineering, Center for Ecosystems and Environmental Sustainability, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
- 2Department of Geosciences and Natural Resource Management, Copenhagen University, 1350, Copenhagen, Denmark
- 3Center for Catchments and Urban Water Research, Norwegian Institute for Water Research, Oslo, Norway
- 4Department of Hydrology, Geological Survey of Denmark and Greenland, 1350, Copenhagen, Denmark
Abstract. Dissolved inorganic carbon (DIC) fluxes across the vadose zone are influenced by a complex interplay of biological, chemical and physical factors. A novel soil mesocosm system was evaluated as a tool for providing information on the mechanisms behind DIC percolation to the groundwater from unplanted soil. Carbon dioxide partial pressure (pCO2), alkalinity, soil moisture and temperature were measured with depth and time, and DIC in the percolate was quantified using a sodium hydroxide trap. Results showed good reproducibility between two replicate mesocosms. The pCO2 varied between 0.2 and 1.1%, and the alkalinity was 0.1–0.6 meq L−1. The measured cumulative effluent DIC flux over the 78-day experimental period was 185–196 mg L−1 m−2 and in the same range as estimates derived from pCO2 and alkalinity in samples extracted from the side of the mesocosm column and the drainage flux. Our results indicate that the mesocosm system is a promising tool for studying DIC percolation fluxes and other biogeochemical transport processes in unsaturated environments.