Dynamic response of soil ecological function in a contaminated site treated by thermal conductive heating: Pollutants removal, nutrition and microbial community restoration

Thermal Conductive Heating (TCH) is a promising approach for remediating contaminated sites, yet its ecological implications and repercussions are underexplored. To addresses this gap, the eight-month study conducted at a site with a 50-year history of chemical manufacturing that was remediated using TCH. We monitored pollutant dynamics, soil properties, and microbial composition to evaluate the efficacy and ecological process of TCH. Results revealed an initial surge in pollutant levels followed by a decline to remediation targets, confirming the effectiveness of TCH. Concurrently, there was an uptick in total nitrogen, available phosphorus, and exchangeable potassium, attributed to soil organic matter breakdown during heating, subsequently supporting microbial recovery. Although microbial richness and diversity were temporarily suppressed by heating, they rebounded naturally during the cooling phase. Proteobacteria and Firmicutes were the predominant taxa due to their strong adaption to harsh environments, while oligotrophic bacteria became enriched under the nutrient-loss environment. Adverse conditions facilitated energy source (chemoheterotrophy and aerobic chemoheterotrophy), while improving conditions enhanced sulfur cycling. Soil properties and temperature are the dominant factors on bacterial composition and microbial functions. This research furnishes a holistic perspective on soil dynamics under TCH and reveals that soil fertility is vital for ecological restoration post-TCH, paving the way for more informed and sustainable ecological revitalization strategies post-thermal desorption treatments. • Long-term in-situ monitoring was conducted post-TCH at a contaminated site. • Pollutant levels initially increased and then decreased with rising temperatures. • Soil fertility fluctuated due to SOM mineralization and microbial consumption. • Microbial communities exhibited spontaneous recovery following TCH treatment. • Soil fertility is a pivotal factor on post-TCH ecological function restoration.