Atmospheric Fate of Pesticides: Heterogeneous Reactivity and Degradation Products
Résumé
After application, 20 to 50% of pesticides can enter the atmosphere through spray drift, volatilization, or wind erosion, posing risks to ecosystems and human health. Once airborne, they can partition between the gas and particulate phases. However, regulatory assessments often overlook their slower degradation on particles, underestimating their persistence. This study investigates the atmospheric fate of nine pesticides commonly used in viticulture (Boscalid, Cypermethrin, Cyprodinil, Deltamethrin, Folpet, Pendimethalin, Spiroxamine, Tebuconazole, and Trifloxystrobin). Using a flow reactor, we exposed pesticide-coated silica particles to ozone and OH radicals, revealing atmospheric half-lives ranging from three days (Cyprodinil) to over a month (Folpet). Furthermore, we identified degradation products on particles using LC-Orbitrap-MS/MS and GC-qMS and detected volatile degradation products in the gas phase using SRI-ToF-MS. Notably, the highly toxic phosgene (Cl2CO) was identified as a degradation product of Folpet and Cypermethrin. These findings underscore the importance of integrating particulate-phase reactivity into risk assessments, as it significantly influences pesticide persistence, transport, and the formation of toxic byproducts.
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