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Quantifying the Variability and Dynamics of Soil Hydromorphism in the Riparian Buffer Systems

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Title: Quantifying the Variability and Dynamics of Soil Hydromorphism in the Riparian Buffer Systems
Author: Prapagar, Komathy
Department: School of Environmental Sciences
Program: Environmental Sciences
Advisor: Heck, Richard.J
Abstract: Soil redox behaviour is fundamental in understanding soil hydromorphology, such as gleying and mottling, which are closely associated with oxidation and reduction status of Fe oxides. Riparian zones are sensitive to seasonal variation in precipitation and water table fluctuation; consequently, soil redox condition fluctuates with time and space. The frequency of soil redox changes is reflected on the dynamics of soil hydromorphism with time and space. The research goal was to explore the potential use of EM-38 electrical conductivity (EC) and magnetic susceptibility (MS) in-field measurement combined with laboratory Fe oxide characterization to understand soil redox dynamics in the Riparian Buffer Systems (RBSs). The study was conducted on three different riparian zones, namely: i) a ‘Grassland riparian buffer system (GR), ii) Undisturbed natural Forest riparian buffer system (UNF), and iii) a Rehabilitated tree land riparian buffer systems (RH), located along Washington Creek, Southern Ontario. Results found that the nature and distribution of Fe oxides differed among RBSs; the UNF soil showed a higher concentration of total free Fe oxides (Fed), poorly crystalline Fe oxides (Feo), and degree of crystallinity (Feo / Fed). The UNF soil also exhibited higher variability of MS for thermomagnetic analysis. The EM-38 magnetic susceptibility showed a positive correlation with Fed in GR and RH soils for both depths (0-25 cm & 25-50 cm). However, the UNF soils deviated from this positive correlation. The in- field soil MS could be related to soil moisture level (EC) and a negative relation was observed between soil MS and soil EC. The UNF soils showed higher EC fluctuation at chamber locations in all three seasons. Greenhouse gas emission varied in relation to the soil EC and MS levels at the chamber locations. CO2 emission also positively responded to soil MS and soil EC positively responded to CH4 emission. The current study findings suggest that soil redox condition is variable among the RBSs with time and space. Soil moisture dynamics found to be the primary factor controlling the soil redox dynamics. The fluctuations of in-field MS over time had provided a useful insight into soil redox behaviour in the RBSs.
URI: https://hdl.handle.net/10214/25794
Date: 2021-05-07
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