The global concern for risk control of organic contaminated sites is becoming more and more prominent. Traditional ex situ remediation techniques are costly and damage the site, seriously destroying the soil structure and ecological functions. Therefore, in situ means of combining material injection and microbial remediation have become a potential pathway for the green, economical, and efficient remediation of contaminated sites. In this work, a 200 m2 test block was selected for the coupled injection of slow-release oxygen materials and microbial agents, and long-term monitoring of groundwater was carried out. The results showed that the slow-release materials could release oxygen for a period of 90 days, which provided an oxidizing environment for microorganisms to rapidly degrade BTEX. For the pre-adapted indigenous degradation bacterial agent test group, the degradation degree of BTEX was up to 98% after 40 days of injection. The results of the application on the field scale proved the feasibility of reinforcing biostimulation for remediation of underground organic contamination through the coupled injection of slow-release oxygen materials and microbial agents. The results provided theoretical and technical support for the in situ remediation of petroleum hydrocarbon-contaminated sites.

Herein, magnetic biochar coupled with Acinetobacter lwoffii DNS32 immobilized pellets (DMBC-P) were synthesized through sodium alginate embedding and fixation, which could fast and completely eliminate atrazine from contaminated farmland soil. Characterization results revealed that DMBC-P exhibited a significant abundance of three-dimensional network porous structures, thereby enhancing the stability and specific surface area of DMBC-P. The application of 0.5 % DMBC-P could completely remove 22 mg/kg atrazine from soil within 4 d under the condition of moisture content of 60 % and soil pH of 7.4. After 5 d of remediation, DMBC-P could be easily extracted from the soil by magnetic separation and still had 100 % removal efficiency for atrazine after 3 rounds of recycling. Moreover, DMBC-P effectively alleviated the oxidative damage of atrazine to soybean seedlings through significantly decreasing the activities of various plants antioxidant enzymes by 27 % to 79 %. Meanwhile, analysis of 16S rRNA revealed a significant increase in the relative abundance of functional microflora such as Acidobacteriota and Chloroflexi at the phylum level, which promoted the growth of soybean seedlings. Additionally, pore filling, hydrogen bonding, and 7C -7C stacking were identified as the primary mechanisms responsible for atrazine adsorption onto DMBC-P. Subsequently, the degrading bacteria DNS32 immobilized on DMBC-P was employed to catalyze the decomposition of atrazine into non-toxic cyanuric acid based on LC -MS. Overall, this study provided a reasonable design of magnetic carbon -based bacterial pellet for atrazinecontaminated soil remediation, which could efficiently remove atrazine and be effectively recycled after remediation.