1. Role of soil pore structure in water infiltration and CO 2 exchange between the atmosphere and underground air in the vadose zone: A combined laboratory and field approach
- Author
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Soledad Cuezva, Juan Carlos Cañaveras, Nicoletta Fusi, Sergio Sanchez-Moral, Jaime Cuevas-González, J. Martínez-Martínez, David Benavente, Giovanni B. Crosta, Angel Fernandez-Cortes, E. Garcia-Anton, Concepción Pla, Pla, C, Cuezva, S, Martinez Martinez, J, Fernandez Cortes, A, Garcia Anton, E, Fusi, N, Crosta, G, Cuevas Gonzalez, J, Cañaveras, J, Sanchez Moral, S, Benavente, D, Universidad de Alicante. Departamento de Ingeniería Civil, Universidad de Alicante. Departamento de Ciencias de la Tierra y del Medio Ambiente, Petrología Aplicada, Ingeniería Hidráulica y Ambiental (INGHA), and Ministerio de Economía y Competitividad (España)
- Subjects
010504 meteorology & atmospheric sciences ,Soil gas diffusion ,Vadose zone ,Soil science ,01 natural sciences ,complex mixtures ,Field capacity ,Underground cave ,Water content ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Macropore ,Soil morphology ,04 agricultural and veterinary sciences ,15. Life on land ,Fluid transport ,6. Clean water ,Leaching model ,Geodinámica Externa ,Infiltration (hydrology) ,Soil water ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,CO2 ,Ingeniería Hidráulica ,Geology ,Petrología y Geoquímica - Abstract
The soils above caves represent a membrane that regulates the connection between the underground environment and the outside atmosphere. In this study, soils from two different field sites (Cueva de Altamira and Cueva del Rull in Spain) are investigated. Field results are analysed and linked to laboratory tests. Several laboratory experiments are performed to quantify CO2 diffusion coefficients and water infiltration rates in these soils under different degrees of soil water saturation and compaction. Tests confirm that the grain size distribution, organic matter content, mineral composition and water content of soils affect gas transport through the soil pore network. Both field and lab results reveal that Altamira soil has a coarser texture and therefore has higher CO2 diffusion coefficients, infiltration rates and hydraulic conductivity values than Rull soil. Rull soil contains a higher proportion of fine particles and organic matter, which explains the lower fluid transport coefficients. When soils are near saturation, fluid transport does not depend on the physical properties of soil but depends on the soil water content. In this state, liquid transport regulates the available space within the soil pores, which leads to a reduction in the gaseous diffusion coefficient of the soil. After rainfall episodes, the connection between the exterior atmosphere and underground cavities is hindered due to a rise in the soil water content, which is responsible for the closure of the overlying membrane. This study demonstrates that soil-produced CO2 reaches the underground atmosphere through diffusion processes that are controlled by the intrinsic properties of soil (porosity, grain size distribution, texture, mineralogy and organic matter content) and soil water content., Departamento de Ciencias de la Tierra y del Medio Ambiente, Universidad de Alicante, España, Geomnia Natural Resources SLNE, España, Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas, España, Department of Earth Sciences, University of London, Reino Unido, Departamento de Biología y Geología, Universidad de Almería, España, Dipartimento di Scienze dell'Ambiente e del Territorio e di Scienze della Terra, Università degli Studi Milano-Bicocca, Italia
- Published
- 2017