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Research Team
Research Team
Trey Smith
Trey Smith
Environmental Earth Science
Warren Forlemu
Warren Forlemu
Environmental Earth Science
Renie Thomas
Renie Thomas
PhD Candidate in Hydrogeology
Dr. Jason Rech
Dr. Jason Rech
Department Chair of Geology and Environmental Earth Sciences
Introduction
Introduction
Wetlands are important ecosystems that can capture the hydrology of a region. A wetland has a high water table relative to other landscapes and the soil is saturated or flooded for most parts of the year. Wetlands can foster complex ecological communities, making them biodiversity hotspots for a region (1).
A fen is a kind of wetland where groundwater is the primary source of water that saturates the soil throughout the year. The movement of water, and the geology of the landscape, must work together to create the conditions supporting a fen. A fen cannot be inundated (standing water at the surface) for long periods of time; must be able to accumulate peat (partially decomposed organic matter); and should support at least grasses, to other forms of vegetation (2).
Fens are important in the Midwest as biodiversity hotspots, but are rare. Many fens have been lost to agriculture and human activity, and changes in climate and land-use can push a wetland out of balance; for a fen, a change in groundwater is harder to control for. There has not been much research looking into the stability of fens, especially here in Ohio.
We examined a central Ohio fen situated near spring-derived waters, to characterize the fen’s formation, and its stability through time, by characterizing its sedimentary record, and analyzing the materials within for any signs on how the environment shifted or persisted through time.
Research Questions
Research Questions
How can we characterize the formation environment and stability through time of the midwestern fen in Mad River township in Mud Run watershed, between Clark and Greene county, Ohio, with XRD analysis?
Study Site
Study Site
Our study site is located in the Mud Run watershed in Mad River township, located within Clark and Greene counties. The fen (“Vibracore Sites”) is located near one of the tributaries of the Mad River (Figure 1). Fens are able to be associated with surface bodies of water, with the source surface water being cut off, leaving only a groundwater connection (2).
Figure 1.
Figure 1.
Map of the Mud Run watershed, Mad River Township, in Clark and Greene Counties, Ohio. The site of the fen is the location marked as “Vibracore Sites.” Pictures of the fen and the process of vibracoring used to extract Core 1 are shown below.
Methods
Methods
Prior to our study, cores were collected in the study site at three locations via vibracoring (Figure 2). Vibracoring is a drilling method that involves driving a vibrating aluminum pipe into a moist substrate, yielding a sediment profile. Core 1 and 3 provided the most substantial profiles, and were further studied. Radiocarbon dating was performed at the lowermost portion of the peat in each core, at ~30 cm depth.
The main focus of this study was an X-ray fluorescence analysis of the core down profile at 5 cm increments. These increments were sliced wet, and yielded 5 cm intervals of core 1 to 100 cm, and core 3 to 109.2 cm. These samples were dried, homogenized, and sifted through a 2mm sieve; core 1 had 20 samples, and core 3 had 22 samples. Each interval was mounted into XRF capsules for analysis. Each increment was analyzed 3 times, and averaged. Elemental data was then compared to observations of the core itself and the literature to infer the fen’s development and prior environmental setting.
Results
Results
The Core Itself
Core 1 and 3, with section descriptions, depth readings, and basal peat ages. A map is also shown where each core was taken. The site of this fen is in a topographically lower position compared to the surroundings.
Main Results from XRF
XRF results in ppm for 5 elements–iron, manganese, calcium, silicon, and sulfur–down profile at 5 cm intervals; a ratio of titanium to zirconium has also been plotted.
Conclusions
Conclusions
FORMATION & PERSISTENCE. The basal peat dating to 6.81-6.88 ka, in conjunction with the thick marl profile below, indicates this wetland environment has persisted since before the Holocene (<11.7 ka). The fen represents an evolution of the wetland’s surrounding environment.
CALCIUM. Elevated levels of calcium in the section below the peat, and the lack of evidence for marine organisms, suggests a marl wetland, where calcium in the form of calcium carbonate precipitated inorganically.
IRON. Relatively high or low iron content represents oxidized and reduced conditions, respectively. Oxidized conditions promote peat decomposition, and reduced conditions promote the removal of mobile iron. Core 1 has been situated near spring fed waters long term, which could correlate to its consistently lower levels of iron; Core 3 is further from the source area, and its peat has experienced more oxidized conditions.
SULFUR & MANGANESE. Large fluctuations in sulfur and manganese could indicate the profile depth at which microbial activity took place at the time of core extraction.
TITANIUM-ZIRCONIUM RATIO. A ratio of immobile elements can indicate the source area of inputs to a system3; a constant ratio indicates autochthonous conditions, or material originating near the fen; a flux in the ratio indicates allochthonous conditions, or material originating further away from the fen. The increase in titanium-zirconium in the fen compared to the marl indicates an increasingly outside source supplying the wetland.
SUMMARY. This fen is part of a longer history of the wetland environment. It is a hub of microbial activity, and an important hydrogeologic marker for this region. Other analyses, such as particle size and total organic carbon, could serve to further detail the history of this wetland.
The following is an image of poster presented at the 2026 Undergraduate Research Forum
References
References
Federal Geographic Data Committee. 2013. Classification of wetlands and deepwater habitats of the United States. FGDC-STD-004-2013. Second Edition. Wetlands Subcommittee, Federal Geographic Data Committee and U.S. Fish and Wildlife Service, Washington, DC. https://www.fws.gov/sites/default/files/documents/Classification-of-Wetlands-and-Deepwater-Habitats-of-the-United-States-2013.pdf
Amon, J. P., Thompson, C. A., Carpenter, Q. J., & Miner, J. (2002). Temperate zone fens of the glaciated Midwestern USA. Wetlands, 22(2), 301-317. https://doi.org/10.1672/0277-5212(2002)022[0301:TZFOTG]2.0.CO;2
Shotyk, W., Krachler, M., Martinez-Cortizas, A., Cheburkin, A.K., & Emons, H. (2002). A peat bog record of natural, pre-anthropogenic enrichments of trace elements in atmospheric aerosols since 12370 14C yr BP, and their variation with Holocene climate change. Earth and Planetary Science Letters, 199(1-2), 21-37. https://doi.org/10.1016/S0012-821X(02)00553-8
NACE Career Readiness Competencies
NACE Career Readiness Competencies
Technology
We were taught to use several lab techniques: X-ray fluorescence, but also including Munsell Soil Color, and particle size analysis (in-prep, not in final results).
Critical Thinking
We had to consider the kinds of things to study for the fen wetland, including tying together literature to fen interpretation, and understanding what the XRF results could mean about the formation and persistence of the fen.
Communication
We had to work in a team to get many aspects of this research completed.
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