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DOM-mediated interaction of DOM-enzyme-pollutants affected the toxicity of combined aged tire wear particles (aged-TWPs) and polyfluoroalkyl substances (PFASs) in soil under successive extreme weather stress
Summary
Tire dust and "forever chemicals" (PFASs) often end up together in soil, and this study found that during extreme weather like heatwaves and floods, natural organic matter in soil can actually help offset some of the toxic effects these pollutants have on soil bacteria and enzymes. This matters because soil health underpins food safety and ecosystem stability, and understanding how climate extremes interact with pollution can help predict risks to the food chain as extreme weather becomes more common. That said, this research was done in soil, not in humans, so more work is needed to know what this means for direct human health effects.
Extreme weather stress is posing growing threats to ecosystems, as they directly disturb soil moisture and affect the toxicity of pollutants, thereby increasing ecological risks. This study investigated how successive extreme climate stress (heatwave, heatwave-drought, and flood) affected the toxicity of co-exposed aged tire wear particles (aged-TWPs) and polyfluoroalkyl substances (PFASs). Results revealed that the combined contamination (COM) significantly altered bacterial diversity and community composition, with the responses varying across the three successive extreme weather stress. Under three extreme weather stress, compared to the control group, the COM did not significantly induce the oxidative stress and cellular membrane damage caused by the individual contamination. The COM increased the aromaticity, hydrophobicity, and humification degree of dissolved organic matter (DOM), particularly under flood stress. The terrestrial esters within DOM significantly shifted the bacterial community. Under three extreme weather stress, the COM increased activities of selected C/N/P cycling enzymes. Interaction of DOM-Enzyme-Pollutants analysis confirmed that DOM, particularly from COM under flood stress, counteracted pollutants-induced conformational loosen of extracellular enzymes in C/N/P cycles and restored enzyme activities. This study provided novel insights into effects of co-exposure of PFASs and aged-TWPs on soil ecosystem under successive extreme weather stress.