Measurement and prediction of gas permeability function for biochar-amended rooted soils
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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Author
Date
2024-05
Department
Major/Subject
Mcode
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Language
en
Pages
12
Series
GEODERMA, Volume 445
Abstract
Biochar amendment have been explored recently for improving hydro-mechanical properties of landfill cover system and enhancing the vegetation for the ecological restoration of post closure landfills. Existing studies have predominantly focused on the hydro-mechanical properties of biochar-amended rooted soils and yet few studies have comprehensively investigated their gas permeability functions in response to unsaturated conditions. The objective of this study is to experimentally and theoretically investigate the coupled effects of biochar and root intensity on CO2 gas permeability in unsaturated soil. Biochar-amended rooted soil was prepared by growing Chrysopogon zizanioides on granite residual soils with biochar at a mas ratio of 5 %. Gas permeability and unsaturated soil properties (i.e., suction and degree of saturation) were monitored simultaneously. Due to the presence of roots, the maximum gas permeability, hydraulic conductivity, and suction increased by 200 %, 600 %, and 50 %, respectively, compared with bare soil. This was attributed to preferential flow, micropore increasement and negative pressure induced by root growth. However, biochar addition decreased the maximum gas permeability and hydraulic conductivity by 21 % and 33 %, respectively. This was attributed to the pore filling function of biochar, increased capillarity due to intrapore of biochar, and presence of surface functional groups in biochar promoting CO2 adsorption. A newly developed model was proposed to predict gas permeability with respected to unsaturated soil properties. It was revealed that the gas permeability function of rooted soils showed a strong dependence on the measured root length density. This study highlights the significance of adopting biochar in mitigation of gas emissions in vegetated landfill cover system.Description
Publisher Copyright: © 2024 The Authors
Keywords
Biochar, CO permeability, Ecological restoration, Root-soil interaction
Other note
Citation
Huang, X, Cai, W & Bordoloi, S 2024, ' Measurement and prediction of gas permeability function for biochar-amended rooted soils ', Geoderma, vol. 445, 116882 . https://doi.org/10.1016/j.geoderma.2024.116882
