Date of Award
Master of Science (MS)
Dr. Samuel Mutiti
Dr. Christine Mutiti
Dr. Allison VadeVoort
The presence of hydric soils is one of the key factors used to identify and delineate wetlands as specified by the United States Fish and Wildlife Service (USFWS). The Indicator of Reduction in Soil (IRIS) Method, accepted by the National Technical Committee for Hydric Soils (NTCHS) can indicate iron reduction in soil which can identify hydric soil for wetland delineation efforts. This thesis was conducted to see if the IRIS method had potential for other uses such as quantifying relative measurements of iron reducing bacteria and to see if a colorimetric scale could be curated to bring less subjection to the method. Real-time Polymerase Chain Reaction (qPCR) and the plate count method were used within the bacteria portion of the study, and X-ray Fluorescence (XRF) was used throughout the iron reduction portion of the current study. Over-estimation of iron reduction did occur using the traditional IRIS protocol and a collection of over 600 photos of IRIS sheet sections were taken and given an average iron concentration for the curation of a future colorimetric scale. General bacterial growth exhibited signs that it may be impacted negatively by the IRIS method. Shewanella oneidensis MR-1 and Geobacter metalireducens exhibited correlations with the iron reduction from the IRIS method and presented that microbial spatial variability amongst the IRIS sheets existed but did faulter the method. The current study serves as a surrogate to other more expensive and complex methods to identify hydric soil, as well as provide more credibility to the role the IRIS method can have within wetland delineation methods.
Everett, Jessica, "Exploring New Methods for Quantifying Soil Reduction, Redox Potential, and Iron Reducing Bacteria Using the IRIS Method in Wetland Soils." (2022). Biology Theses. 28.
Available for download on Monday, July 28, 2025