In a study published in Ecotoxicology and Environmental Safety, Wang et al., investigated the impact of freeze-thaw aged biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More on soil contaminated with di-(2-ethylhexyl) phthalate (DEHP), a common plasticizer. The research focused on Mollisols, a valuable soil type particularly important for grain cultivation in Northeast China, where plastic film use has led to DEHP pollution.  

The authors compared fresh biochar (BC) with freeze-thaw aged biochar (FBC), prepared to mimic winter conditions in Northeast China. They conducted pot experiments to assess how freeze-thaw aging affects biochar’s ability to detoxify soil, improve soil properties, and influence the soil microbial community.  

The results showed that freeze-thaw aged biochar significantly improved Mollisols. After 28 days, FBC reduced DEHP content by an impressive 99.08%. Metagenomic sequencing revealed that FBC increased microbial diversity and abundance, particularly in beneficial bacteria like Proteobacteria, Bacteroides, and Firmicutes.   The study also found that FBC upregulated genes involved in DEHP degradation and nitrogen cycling, indicating that it enhances the soil’s natural ability to recover. Furthermore, experiments with pakchoi, a leafy vegetable, demonstrated the feasibility of using FBC to improve agricultural productivity in high-latitude regions.  

This research provides valuable insights into using biochar, particularly after freeze-thaw aging, to remediate DEHP-contaminated Mollisols. The findings suggest that this approach can improve soil health and support sustainable agriculture in cold regions.  

SOURCE: Wang, L., Zhang, W., Yao, J. X., Qi, Z., Liu, Y., Li, Z., … & Zhang, Y. (2025). Effect of freeze-thaw cycle aging on biochar application in DEHP contaminated Mollisols: Insights from soil properties and microbial community. Ecotoxicology and Environmental Safety, 294, 118082.