Effectiveness of Activated Carbon for Immobilization of Bromacil and Tebuthiuron Following Accelerated Freeze–Thaw Weathering

The long-term effectiveness of activated carbon (AC) in immobilizing soil-applied herbicides remains a critical concern for effective management practices for sites impacted by residual sterilants, such as bromacil and tebuthiuron. This study evaluates the sustained performance of AC amendments in reducing herbicide mobility and phytoaccessibility. Herbicide concentrations and leaching potential following AC application were assessed. Results demonstrate that AC significantly reduced detectable levels of bromacil and tebuthiuron in soil, with immobilization effects persisting after physical weathering. In many cases, AC amendment lowered phytoaccessible sterilant concentrations below limits outlined in the Alberta Tier 1 Soil Remediation Guidelines. The findings support further evaluation of AC as a remediation strategy under field conditions, with implications for practical reclamation approaches in the Canadian climate. This work advances soil amendment technologies for herbicide immobilization and reduction in herbicide bioavailability.