Remediating Soil with the Help of Chromatography

Soils are essential for life. They play a key role in the human life support system through a variety of roles. But like many parts of the planet and our ecosystems - we have not always treated soil with the respect necessary for a key component required for human life to thrive. As population grows and the demand for land grows, we need to clean up land we have previously used and abused.

A recent paper published in the journal Energetika reports on how Lithuanian researchers have investigated a new method to help clean up contaminated land. The paper - Remediation of organochlorine pesticides contaminated soil using thermal plasma - describes experimental research into remediating soils polluted with organochlorides using thermal air and water vapour plasmas.

Soils - helping stabilise life on Earth

Soils mainly consist of particles of minerals and rock alongside organic matter. It develops over many years due to the action of different physical, chemical and biological processes. Soils help the environment by cleaning up rainwater and starting the filtering process that eventually leads to clean water coming out of our taps. Soil also help the natural environment to provide protection against flooding by holding excessive rainwater and releasing it slowly. But the main quality we use is that soil provides plants with a foothold for their roots allowing them to absorb nutrients and water from the soil - helping to feed us.

Unfortunately, we have not always left soils in a healthy condition when we have used them. Brownfield sites litter towns and cities where contaminated soil is left after manufacturing industries have left. And some of our previous farming practices have left soils contaminated with the chemical nasties we used to use as pesticides. As some of these residual pesticides can be taken up by the crops that grow on them and harm humans and animals that eat those crops - we need to clean up the soil so we can use it again.

Remediating soils for future use

There are several methods that can be used to remediate soils including bioremediation and air sparging. But these methods are time consuming and are limited in some soil types and environmental conditions. The Lithuanian researchers investigated new methods including thermal air and water vapour plasma. Thermal plasmas provide radicals (OH, H and O ions) that can react quickly and degrade residual pesticides in soil.

The team analysed the concentrations of organochlorides in soil before and after treatment using a variety of methods including gas chromatography-mass spectrometry. The use of mass spectrometry with complex sample matrix is discussed in the article, Recent Advances to Conquer Analytical Challenges with High-Resolution, Accurate Mass Spectrometry.  The team found that organochloride residues were significantly reduced after plasma treatment of the soils - indicating that thermal air or water vapour plasmas could be used to quickly clean up our dirty soils in the future