CO2 fluxes to aquifers beneath cropland:merging measurements and modeling

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Abstract

Carbon dioxide (CO2) fluxes in the vadose zone are influenced by a complex interplay of biological, chemical and physical factors. To determine the controls behind dissolved inorganic carbon (DIC) percolation to aquifers, CO2 fluxes in planted soil mesocosms were described with the SOILCO2 model formulation (Šimůnek et al., 1993) that was implemented into the HP1 module of the Hydrus 1D software package. Water flow, cation exchange, and supersaturation for amorphous aluminum hydroxide were modeled. The model provided a good fit to measured water content and outflow time series. Also, the measured DIC efflux, CO2 partial pressure (pCO2), and CO2 efflux were simulated well throughout most of the experimental period. However, alkalinity was significantly overestimated, indicating additional acidity production in the mesocosms. CO2 fluxes were strongly influenced by a higher root growth in the mesocosms as compared to the field, which caused steep increases in pCO2. The model showed that the high pCO2 triggered weathering of calcite, leading to increases in alkalinity. DIC percolation lacked accompanying increases, indicating an overestimation of the DIC percolation estimated from measured pCO2, alkalinity, and water flux.

Details

Original languageEnglish
Title of host publicationProceedings of the 4th International Conference HYDRUS Software Applications to Subsurface Flow and Contaminant Transport Problems
Place of PublicationPrague, Czech Republic
Pages355-363
Publication statusPublished - Jul 2013
Event4th International Conference HYDRUS Software Applications to Subsurface Flow and Contaminant Transport Problems - Czech University of Life Sciences, Prague, Czech Republic
Duration: 21 Mar 201322 Mar 2013

Conference

Conference4th International Conference HYDRUS Software Applications to Subsurface Flow and Contaminant Transport Problems
Country/TerritoryCzech Republic
CityPrague
Period2013-03-212013-03-22

Keywords

  • Carbon dioxide fluxes, HP1, HYDRUS-1D

ID: 282295