Date of Award

2023-05-01

Degree Name

Master of Science

Department

Geological Sciences

Advisor(s)

Anthony J. Darrouzet-Nardi

Abstract

Critical zone processes in drylands play a crucial role in the global carbon cycle, and one of the most important processes is soil CO2 efflux at the interface between soils and the atmosphere, which represents a main pathway for loss of carbon. Predicting the carbon dynamics at this interface is challenging due to the complexity of belowground processes, which include both biotic (soil respiration) and abiotic (calcite precipitation) production of CO2, as well as transport processes that include both diffusive and advective components. In this study, we aimed to investigate the contribution of soil air displacement to soil CO2 efflux during pulsed moisture events (natural rainfall, artificial rainfall, and irrigation) in a shrubland and agricultural site. To achieve this, we took simultaneous measurements of both diffusion using soil CO2 concentrations (Fick's Law calculations) and total CO2 efflux at the surface (eosFD sensors) and compared the two. Our results demonstrate that the introduction of water to the soil during pulsed moisture events immediately increases CO2 effluxes, and furthermore, these increases cannot be attributed to diffusion processes. We show that displacement plays a consistent role in both agricultural and shrubland sites during various types of pulsed moisture events, highlighting the importance of transport processes such as displacement in understanding the timing of CO2 release from these soils.

Language

en

Provenance

Recieved from ProQuest

File Size

p.

File Format

application/pdf

Rights Holder

Briana Alyce Salcido

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