Electronic Theses and Dissertations Archive

Date

2026

Document Type

Thesis

Degree Name

Master of Science

Department

Earth Sciences

Committee Chair

Gary Stinchcomb

Committee Member

Rachel Lombardi

Committee Member

Youngsang Kwon

Abstract

Secondary soil iron-manganese concentrations (FMC) form because of soil redox reactions and influence the cycling and availability of key nutrients and toxins in wetland ecosystems. However, the effects of landscape position and soil age on FMC formation are not well understood. This study examines the µ-XRF spectroscopy of FMC from soils sampled along terrace, floodplain, and channel landscapes in a bottomland hardwood forest in the Mississippi Embayment of western Kentucky. We found that FMC area is linked to epi- and endosaturation. The 25 µm resolution µ-XRF chemical maps show decreasing area with depth in episaturated conditions along the terrace and increasing area with depth in endosaturated conditions along the floodplain and channel. Phosphorus is significantly enriched in FMC and co-located with Fe-enriched zones, compared to Mn-enriched zones. The P enrichment increases with increasing mean soil organic carbon age and varies with landform hydrologic patterns. Vegetation also influences the chemistry of FMC. Bald cypress soils in the channel have FMC with distinct accumulations of K and Ca that contrast with barren channel soil surfaces and post oak terrace and mixed deciduous floodplains. The µ-XRF results show that in addition to landscape, hydrology, and age, biological influences are key in understanding the interplay of nutrient cycling and carbon storage in freshwater wetland environments.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest/Clarivate.

Notes

Open Access

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