Wildfire smoke, consisting primarily of organic aerosols, has profound impacts on air quality, climate and human health. Wildfire organic aerosol evolves over long-time photochemical oxidation due to the formation and ageing of secondary organic aerosol, which substantially changes its magnitude and properties. However, there are large uncertainties in the long-time ageing of wildfire organic aerosol because of the distinct ageing behaviours of the complex organic emissions. Here we developed an oxidation model that simulates the ageing of wildfire organic emissions in the full volatility range on a precursor level and integrated insights from single-species ageing and wildfire emissions ageing experiments and field plume observations to constrain the long-time ageing of wildfire organic aerosol. The model captured the enhancement of organic aerosol mass (2–8 times) and oxygen-to-carbon ratio (1–4 times) in the wildfire ageing experiments. It also reconciled a long-standing discrepancy between field and laboratory observations of the magnitude of secondary organic aerosol formation. The model indicated large emissions-driven variations in precursor contributions to secondary organic aerosol, which further evolve with long-time ageing. The estimated global wildfire secondary organic aerosol production (139 ± 34 Tg per year) was much higher than previous studies omitting or under-constraining long-time ageing.

International audienceField campaigns were conducted to determine indoor emissions of carbonaceous aerosols and other air pollutants from household fuel burning in southwest China. “1-h peak” concentrations of CO, PM1.0, PM2.5 and PM10 were 14.0 ppm, 200, 220, and 260 µg/m3 for wood and 10.3 ppm, 80, 110, and 180 µg/m3 for coal, respectively. Daily average levels of CO, PM1.0, PM2.5 and PM10 were 5.7 ppm, 100, 110, and 160 µg/m3 for wood and 6.0 ppm, 50, 70, and 100 µg/m3 for coal, respectively. For wood and coal, particle size distribution show a prominent Aitken mode with peaks at around 40–80 nm. Emission factors of BC and OC were 0.57 and 2.69 g/kg for wood and 0.01 and 0.31 g/kg for coal, respectively. The total BC emissions from wood and coal (anthracite) burning in China were 63.3 Gg in 2000 and 81.6 Gg in 2005, respectivel

The efficient degradation of antibiotics in wastewater is critical for addressing global water pollution challenges. Herein, we report a dual-atom Fe-Co catalyst anchored on a nitrogen-doped carbon matrix (FeCo/NC), which demonstrates superior performance in peroxymonosulfate (PMS) activation and tetracycline (TC) degradation. This system achieves a remarkable 91.2% TC removal efficiency, significantly outperforming single-atom catalysts. Mechanistic investigations reveal that FeCo/NC induces a unique spin-state reconstruction, optimizing its electronic structure and shifting the oxidative mechanism from a radical-driven pathway to a singlet oxygen (¹O₂)-dominated nonradical process. Theoretical insights from density functional theory (DFT) calculations confirm the preferred ¹O₂ generation pathway at FeCo active sites, with reduced energy barriers that enhance catalytic activity. Toxicological evaluations validate that TC degradation intermediates exhibit minimal ecological risks, reinforcing the environmental safety of this approach. The long-term stability of the FeCo/NC/PMS system was evaluated via a continuous-flow photocatalytic reactor, the above results reflect the superior catalytic activity and stability of the FeCo/NC/PMS system. This work establishes a paradigm for designing advanced dual-atom catalysts and provides critical insights for developing eco-friendly solutions to antibiotic-contaminated wastewater treatment.

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