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 (pCO(2)), 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 pCO(2) 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 pCO(2) 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.
Biogeosciences, 2014, Vol 11, Issue 4, p. 1077-1084
ECOLOGY; GEOSCIENCES,; SOIL CO2 CONCENTRATIONS; UNSATURATED ZONE; SANDY AQUIFER; DIOXIDE; ECOSYSTEM; ACIDIFICATION; RESPIRATION; GROUNDWATER; PROFILES; EXCHANGE; biogeochemical transport; groundwater percolation; mesocosm column; mesocosm drainage flux; pore water alkalinity; soil mesocosm system; unsaturated environment; vadose zone; dissolved inorganic carbon; partial carbon dioxide; 52801, Soil science - General and methods; mesocosm approach applied and field techniques; sodium hydroxide trap applied and field techniques; Methods and Techniques; Soil Science