Soil research collaboration findings relevant to landmine clearing and fracking

“This work demonstrates the importance and impact of experts working together across disciplines, for instance, chemistry, explosives science, soil science and forensic science,”

Blowing up landmines and other undetonated explosives may be safer and more environmentally friendly than physically removing them from contaminated land, according to new research carried out by the University of Dundee, in partnership with colleagues at the James Hutton Institute, Curtin University and ChemCentre, Australia.

Explosives can be a common soil contaminant at a range of sites, including military training facilities, manufacturing plants and post and current conflict zones. If these areas are to be brought back into productive use, then they need to be cleared of the explosive and any toxic residue of explosives which may remain in the soil.

The research, carried out by an interdisciplinary team of scientists from the University of Dundee, the James Hutton Institute in Aberdeen and ChemCentre and Curtin University, both in Australia, saw the team stage a series of controlled explosions to explore how different soils behave and what happens to the explosive residue as a result.

Their results suggest that residues are more quickly and effectively bio-remediated when explosives are detonated rather than when they are chemically or physically removed, a process that incurs both expense and risk.

“Our research investigates what happens to explosives present in soils following an actual detonation and compares this to the fate of explosives spiked into undetonated soils,” said Professor Niamh Nic Daeid, Director of the University of Dundee’s Leverhulme Research Centre for Forensic Science.

“The effects of detonations on the physical properties of the soils were also examined. When explosions occur, the soil is fractured and dispersed in such a way that allows removal of TNT by soil-borne bacteria, resulting in increased effectiveness in the removal of toxins that may cause adverse environmental effects.”

Professor Lorna Dawson, Principal Soil Scientist and Head of Forensic Soil Science, James Hutton Institute, added: “The detonations were shown to increase soil porosity, causing the surface area available for bio-degradation to occur to increase.”

Professor Niamh Nic Daeid said: “This increased porosity is directly related to an increased rate of TNT loss within the detonated soils. This discovery potentially exposes novel remediation methods for explosive contaminated soils where actual detonation of the soil significantly promotes subsequent TNT degradation.”

The findings, published in the journal PLOS One, suggest that pores present within some soil types may act as ‘sinks’ for soil contaminants such as TNT, reducing its availability for subsequent microbial degradation of the contaminant. By physically detonating the soil, these pores increase in size and surface contact area allowing for an increased bio-degradation and consequent reduction of the TNT to occur. The findings may also have possible implications for the fracking industry.

According to Professor Nic Daeid, because of the way the research examined the effects of detonation of subsurface soil, it might also have implications for other high-energy soil disruption, such as fracking, which should be pursued and explored.

“This work demonstrates the importance and impact of experts working together across disciplines, for instance, chemistry, explosives science, soil science and forensic science,” Professor Dawson commented.

Paper: Explosive detonation causes an increase in soil porosity leading to increased TNT transformation, by Holly A. Yu, Niamh Nic Daeid , Lorna A. Dawson, David A. DeTata, Simon W. Lewis. PLOS One, https://doi.org/10.1371/journal.pone.0189177.