Technical Note: Mesocosm approach to quantify dissolved inorganic carbon percolation fluxes

[摘要] Dissolved inorganic carbon (DIC) fluxes across the vadose zone areinfluenced by a complex interplay of biological, chemical and physicalfactors. A novel soil mesocosm system was evaluated as a tool for providinginformation on the mechanisms behind DIC percolation to the groundwater fromunplanted soil. Carbon dioxide partial pressure (pCO₂), alkalinity, soilmoisture and temperature were measured with depth and time, and DIC in thepercolate was quantified using a sodium hydroxide trap. Results showed goodreproducibility between two replicate mesocosms. The pCO₂ varied between0.2 and 1.1%, and the alkalinity was 0.1–0.6 meq L⁻¹. The measured cumulativeeffluent DIC flux over the 78-day experimental period was 185–196 mg L⁻¹ m⁻² and in the same range as estimates derived frompCO₂ and alkalinity in samples extracted from the side of the mesocosmcolumn and the drainage flux. Our results indicate that the mesocosm systemis a promising tool for studying DIC percolation fluxes and otherbiogeochemical transport processes in unsaturated environments.

[学科分类] 地球化学与岩石