Microbial community dynamics drive soil functional recovery after in-situ gas-thermal remediation of co-contaminated soil

At present, thermal desorption technology has been widely used in the remediation of contaminated sites, but heating may alter the physical and chemical properties of the soil, posing potential risks to soil health. In this study, in-situ gas-thermal remediation technology was used to repair the co-contaminated soil of a coke plant in Jiangsu Province. The removal of soil pollutants, the change of soil basic properties and the change of microbial community structure were evaluated. The results showed that the removal effect of in-situ gas-thermal remediation was significant, the organic pollutants were basically eliminated, and the concentration of arsenic decreased by 68.15 %. Soil pH recovered to neutral, urease activity increased significantly. The diversity and uniformity of the microbial community decreased, but the structure and function of the community partially recovered to a state similar to that of uncontaminated soil, and Firmicutes, such as Bacillus subtilis and Lysinibacillus, were significantly enriched. The microbial co-occurrence network showed microbial community also becomes more stable, and the soil function was transforming towards ecological restoration type. This study provides new insights into soil functional recovery after in-situ gas-thermal remediation.