Di(2-ethylhexyl) phthalate (DEHP), a complex structure with high toxicity, is a common or-ganic pollutant. This study investigated the effects of fresh biochar (FBC), and freeze-thaw cycled aged biochar (FTC-BC) on DEHP-contaminated soils using a pot experiment. The spe-cific surface area of FBC increased from 145.20 to 303.50 m 2 /g, and oxygen-containing func-tional groups increased from 1.26 to 1.48 mol/g after freeze-thaw cycles, greatly enhancing the adsorption of DEHP by biochar in the soil. The comprehensive radar chart evaluation showed that FBC and FTC-BC reduced DEHP growth stress and improved the soil properties. Compared with FBC, FTC-BC performed better in protecting the normal growth of pakchoi and improving soil properties. In addition, the application of biochar increased the diver-sity and abundance of bacteria in the DEHP-contaminated soil and changed the composi-tion of the soil bacterial community. The partial least squares path model (PLS-PM) showed that adding biochar as a soil remediation agent significantly positively impacted soil nutri-ents and indirectly reduced the DEHP levels in soil and plants by increasing soil microbial diversity. Compared with FBC, FTC-BC creates a more satisfactory living environment for microorganisms and has a better effect on the degradation of DEHP in the soil. This study provides a theoretical basis for future biochar remediation of DEHP-contaminated soils in cold high-latitude regions. (c) 2023 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.
