Author ORCID Identifier

https://orcid.org/0009-0009-0705-6625

Semester

Spring

Date of Graduation

2023

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Omar I. Abdul-Aziz

Committee Member

Radhey Sharma

Committee Member

P.V. Vijay

Abstract

Freshwater wetlands can contribute significantly to the global carbon budget as a net source or sink of the major greenhouse gas (GHG) fluxes such as carbon dioxide (FCO2) and methane (FCH4). The amount of GHG fluxes in the freshwater wetlands is highly variable and depends on a range of environmental drivers. These wetlands are commonly hypothesized to be net sinks (i.e., burial) of FCO2 and net sources (emission) of FCH4 at the monthly to annual scales. Understanding the environmental controls on the wetland GHG fluxes is essential for an accurate estimation of the global GHG budget, which is often used as a pivotal measure to reduce GHG emissions and enhance carbon sequestration. In this study, we analyzed FLUXNET data from 38 freshwater wetlands located across the globe to investigate the relationships of monthly-scale GHG fluxes with various climatic and ecohydrological drivers. Data analytics with multivariate pattern recognition techniques—including principal component analysis, factor analysis, and partial least squares regression— were performed to identify and quantify the dominant controls of wetland FCO2 and FCH4 fluxes. The environmental controls on the GHG fluxes in freshwater wetlands were found to highly vary based on the climatic zones. In the tropical (i.e., mega thermal) zone, the GHG fluxes were overall primarily controlled by photosynthetically active radiation (PAR), soil temperature (TS), wind speed (WS), friction velocity (USTAR), and vapor pressure deficit (VPD). However, the latent heat flux (LE) and VPD, alongside PAR, TS, and USTAR, exhibited the dominant controls on the GHG fluxes in the dry (or arid) zone wetlands. Both GHG fluxes in wetlands of the temperate (or mesothermal) zone were mainly controlled by water table depth (WL), TS, and LE. Surprisingly, PAR did not appear to be a strong driver of the monthly averaged fluxes in the temperate wetlands. In contrast, PAR, LE, TS, WS, and USTAR were the primary controlling factors of the GHG fluxes in wetlands representing continental (or microthermal) climates. However, in wetlands of the polar (alpine) region, sensible heat flux (H) had a strong linkage with the GHG fluxes, alongside the controls of PAR, TS, WS, VPD and USTAR. These findings and new knowledge can help inform wetland management and conservation strategies, particularly in the context of climate and land cover changes. Effective management and conservation of wetlands can help reduce GHG emissions, thereby contributing to the mitigation efforts on global warming.

Embargo Reason

Publication Pending

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