Soil contamination from per- and polyfluoroalkyl substances, often called forever chemicals, presents a massive global environmental challenge because these synthetic compounds are exceptionally mobile and do not break down naturally. A highly common strategy to manage contaminated soils involves applying carbon-based sorbents that act like chemical magnets to bind the pollutants in place and prevent them from leachingLeaching is the process where nutrients are dissolved and carried away from the soil by water. This can lead to nutrient depletion and environmental pollution. Biochar can help reduce leaching by improving nutrient retention in the soil.   More into groundwater. However, because these cleaning materials are left in the ground indefinitely, scientists have long questioned how natural weathering over decades might alter their performance. To address this uncertainty, the researchers simulated decades of natural physical, chemical, and biological wear using accelerated laboratory weathering methods on six common carbon-based cleaning agents.

The findings revealed that simulated physical weathering, such as repeated wetting and drying cycles, and biological weathering, driven by soil microbes, caused the most significant declines in cleanup performance. Microscopic imaging confirmed that these weathering processes physically block the microscopic pores of the carbon materials through soil particle accumulation and biofilm formation, which limits the available surface area for capturing pollutants. The type of cleaning material used played a major role in how well the treatment held up, with powdered activated carbon proving to be the most durable and resistant to aging, whereas biochar was highly susceptible to losing its binding capacity.

Furthermore, the research demonstrated that when the cleaning materials and soils weathered together, the performance was highly dependent on the soil type. Chemical weathering caused a notable decline in binding efficiency in sandy soils, while physical weathering had a harsher impact on clay-rich soils. Despite these deliberately intense weathering simulations designed to mimic extreme conditions, activated carbon-based materials proved to be remarkably resilient. They successfully maintained high containment levels, trapping more than eighty-five percent of the target compounds even in highly contaminated soils. This work provides crucial evidence that carbon-based stabilization remains a reliable, durable, and highly effective option for the long-term management of contaminated sites under diverse environmental conditions.

Source: Kabiri, S., Bowles, K. C., Bhat, S., & Navarro, D. A. (2026). Effect of physical, chemical, and biological aging on activated carbon and biochar properties and PFAS immobilisation in soils. Journal of Hazardous Materials.