Degradation of four pesticides by ozonation under field conditions and assessment of its influence on soil microbial activity

The application of pesticides is a common practice for pest control. Either its excessive use or by performing improper farming practices, the occurrence of residual levels of these compounds in soil has become a global issue due to their negative impacts on environment and human health. This work was aimed to assess the effectiveness of ozonation technique for the remediation of soils polluted with boscalid, chlorantraniliprole, flonicamid and metribuzin residues at field conditions and the impact of its application on microorganism activity of the soil. Trial was conducted in plots located in a greenhouse, exposing polluted soil to different treatments during the winter season. Four different treatments were applied: S (soil covered with polyethylene film), SOD (film covering and deep-ozonation), SOSD (film covering and superficial-deep-ozonation) and C (no treatment, control). Better degradation efficiency was found for SOSD treatment (dual ozone application), where remaining percentages ranged from 13.2 % to 33.1 %. The main transformation products (TPs) were monitored through the remediation experiment, showing residual levels of six intermediates in all treatments. Further, the overall activity of the soil microbial community was evaluated through basal respiration, with SOSD showing the greatest microbial activity. The results suggest that ozonation could be proposed as an alternative technical approach for the remediation of pesticide polluted soils.