Interdisciplinary team studies decomposition effects on soil

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Postdoctoral researcher Stacy Taylor conducts research on soil samples collected from the Anthropological Research Facility. Credit: UT, Knoxville

Forensic researchers at UT Knoxville’s famous Anthropological Research Facility, popularly known as the “Body Farm,” have made headlines for decades in their discoveries of what happens to human bodies after death. Now, a multidisciplinary team—engineers, soil scientists, and biologists—digs in with them for a deeper look at what happens to the soil underneath a decomposing body.

Their study, “Soil Elemental Changes During Human Decomposition,” published in June 2023 by PLOS One, could benefit investigators searching for in remote or hard-to access-vegetated areas.

“This study was part of a larger project where we were investing in the vicinity of a decomposing body,” said Jennifer DeBruyn, co-author and professor in the Department of Biosystems and Soil Science (BESS). “Our bodies are concentrated in nutrients and other elements compared to the surrounding environment. As they break down, these nutrients are released into the environment, resulting in changes to and vegetation nearby.”

A greater understanding of how and when soil and vegetation changes in the presence of decomposing human remains may offer clues to both locating bodies and estimating how long they have been there.

To test their ideas, this study asks: What elements are released from the during and how does it influence the local soil environment?

“We have previously looked at the major elements of the body, namely carbon and nitrogen,” said DeBruyn, “But we know there are lots more in our bodies.”

The next most abundant elements in the body are sulfur, phosphorus, sodium, and potassium. As the in test bodies decomposed, the team observed an expected pulse of these elements in the soils as they were released into the environment.

“What we were surprised to see was that we also had higher concentrations of calcium and magnesium than what we would expect from the input of the body alone,” said Stacy Taylor, lead author on the study and a postdoctoral researcher in DeBruyn’s lab. “While we do have calcium (Ca) and magnesium (Mg) in our bodies, much of it is tied up in our bones, which would take years or decades break down. Soils have capacity to bind cations like Ca2+ and Mg2+, so our hypothesis is that the changing conditions resulted in the release of these elements from the soil itself.”

They were also surprised to see an increase in some trace metals a few months into the soil testing, after soft tissues were largely decomposed.

“Again, the concentrations in soil were higher than what we would expect based on just what would be coming from the body,” said Taylor. “Decomposition fluids result in a gradual acidification of the soil over time, so our hypothesis is that as the pH was dropping, these trace metals were slowly being solubilized from mineral complexes in the soil.”

The big-picture take-away from their study could lead to new approaches in finding missing persons or in determining how long remains have been in a location.

“This study was an important documentation of the types of elements released during human decomposition and how they changed over time,” said DeBruyn. “It contributes to our broader understanding of local environmental changes during human decomposition, which may ultimately help us understand the timing of decomposition in cases where human remains are found outdoors.”

DeBruyn and her students and postdocs have been conducting research at the Anthropological Research Facility for over a decade, investigating the microbiological and environmental changes during human decomposition.

Their team for the study included DeBruyn, Taylor, and Michael Essington from BESS; Scott Lenaghan and Neal Stewart from the Center for Agricultural Synthetic Biology within the UT Institute of Agriculture; Amy Mundorff and Dawnie Steadman of the Forensic Anthropology Center, and Adrian Gonzalez, manager of the Water Quality Core Facility (WQCF) in the Department of Civil and Environmental Engineering.

The WQCF analyzed hundreds of soil samples that originated from underneath deceased human donors—those whose decision to volunteer their remains offers ongoing contribution to the furthering of this investigative science.

More information:
Lois S. Taylor et al, Soil elemental changes during human decomposition, PLOS ONE (2023). DOI: 10.1371/journal.pone.0287094

Provided by
University of Tennessee Institute of Agriculture

Interdisciplinary team studies decomposition effects on soil (2023, August 11)
retrieved 12 August 2023

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Newly planted vegetation accelerates dune erosion during extreme storms, research shows

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OSU College of Engineering researchers at the O.H. Hinsdale Wave Research Laboratory found that dunes with newly planted vegetation scarped faster than bare dunes. Photo provided by Meagan Wengrove, CoE. Credit: OSU College of Engineering

Newly planted vegetation on coastal sand dunes can accelerate erosion from extreme waves, a study involving researchers from the Oregon State University College of Engineering suggests.

The authors note the findings run counter to the widely accepted paradigm that vegetation always acts to reduce erosion on , the first line of storm defense for landscapes that are among the world’s most ecologically important and economically valuable.

The experiments involved building beach dune profiles 70 meters long and 4.5 meters high and subjecting them to storm waves in a 104-meter-long flume at OSU’s O.H. Hinsdale Wave Research Laboratory.

Researchers spent six months growing coastal switchgrass, a common dune plant known scientifically as Panicum amarum, within the flume before beginning wave testing.

“This project required the participation of five from different universities nationwide, about 10 coastal scientists and 15 grad students working together in our large wave flume for almost nine months,” said Pedro Lomonaco, director of the wave research lab. “Various instruments measured the wave conditions, sediment transport, underground water level changes, beach profile evolution and relevant metrics. The experiments we conducted represent a landmark for testing at a large scale.”

OSU College of Engineering researchers at the O.H. Hinsdale Wave Research Laboratory found that dunes with newly planted vegetation scarped faster than bare dunes. Credit: OSU College of Engineering

Findings of the study were published June 14 in Science Advances.

The research is crucial, notes Oregon State’s Meagan Wengrove, because the United States coastline is dotted with communities trying to protect themselves from storms by planting vegetation on dunes in an attempt to make the dunes higher and more stable.

The authors say the existing body of dune research shows that vegetation size, density and diversity are associated with less erosion, but those studies have been limited to relatively small wave events over time scales measured in minutes.

“In our research we found that a newly planted coastal dune that does not have a very established root structure scarped faster than a bare dune with the same sand size and compaction,” said Wengrove, assistant professor of civil and construction engineering.

Scarping is when a , or other hillside, erodes into a steep shape that’s vertical or close to it. A scarped dune is inherently unstable, putting structures and roadways near it at risk and threatening the surrounding ecosystems.

OSU College of Engineering researchers at the O.H. Hinsdale Wave Research Laboratory found that dunes with newly planted vegetation scarped faster than bare dunes. Credit: OSU College of Engineering

“We still need to learn more about how different levels of vegetation establishment influence coastal dune vulnerability to wave-driven erosion, but this work is an important step toward understanding the role vegetation plays,” she said.

The collaboration led by Rusty Feagin of Texas A&M University found that while vegetation initially created a to wave energy during a severe storm situation, it also increased water penetration into the sediment bed, which induced destabilization and sped up scarp formation. “Once a scarp forms, the erosion accelerates even more,” Wengrove said.

More information:
Rusty Feagin, Does vegetation accelerate coastal dune erosion during extreme events?, Science Advances (2023). DOI: 10.1126/sciadv.adg7135.

Newly planted vegetation accelerates dune erosion during extreme storms, research shows (2023, June 14)
retrieved 14 June 2023

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