首页|Processes involving soil CO2 dynamic in a sector of Chaco-Pampean plain,Argentina:An isotope geochemical approach
Processes involving soil CO2 dynamic in a sector of Chaco-Pampean plain,Argentina:An isotope geochemical approach
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The magnitude and spatial variability of CO2 surface emissions and processes involving CO2 released to the atmosphere from the soils are relevant issues in the con-text of climate change.This work evaluated CO2 fluxes and 13C/12C ratio of vegetation,organic matter,and soil gases from no disturbed soils of Chaco Pampean Plain(Argentina)with different soil properties and environmental conditions(PL and PA units).Soil organic decomposition from indi-vidual layers was accompanied by δ13C of total organic car-bon(δ13C-TOC)values more enriched to depth.δ13C-TOC values in the upper soil profile～ca.0-15 cm were like the plant community of this area(～-33 to-29 ‰)while δ13C-TOC varied stronger bellow horizon A,till～-24‰.Bothδ13C-TOC and soil δ13C-CO2 were similar(～-24 to 26 ‰)at deeper horizons(～50-60 cm).Toward the superficial layers,δ13C-TOC and δ13C-CO2 showed more differences(till～4 ‰),due influence of the diffusion process.Hori-zon A layer(～0-20 cm)from both PL and PA units con-tained the most enriched δ13C-CO2 values(～-15-17 ‰)because atmospheric CO2 permeated the soil air.A simple two-component mixing model between sources(atmos-pheric δ13C-CO2 and soil CO2)confirmed that process.Isotopically,CO2 fluxes reflected the biodegradation of C3 plants(source),diffusive transport,and CO2 exchange(atmosphere/soil).Soil moisture content appeared as a deter-mining factor in the diffusion process and the magnitude of CO2 surface emissions(12-60 g.m-2.d-1).That condition was confirmed by CO2 diffusion coefficients estimated by air-filled porosity parameters and soil radon gradient model.
Instituto de Geociencias Básicas,Aplicadas y Ambientales de Buenos Aires(IGEBA),Facultad de Ciencias Exactas y Naturales,Universidad de Buenos Aires,CABA,Intendente Güiraldes 2160,Pabellón Ⅱ,Piso 1,C1428EGA Ciudad Universitaria,Argentina
Instituto de Geocronología y Geología Isotópica(INGEIS),Facultad de Ciencias Exactas y Naturales,Universidad de Buenos Aires,CABA,Intendente Güiraldes 2160,Pabellón INGEIS,C1428EGA Ciudad Universitaria,Argentina
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