Kinetic studies of heterogeneous reactions of particulate phosmet and parathion with NO3 radicals

Heterogeneous atmospheric degradation of current-use pesticides by nitrate radicals

“…Unfortunately, because of the lack of data, these comparisons are done only with other pesticides. Literature data about the heterogeneous degradation of pesticides by NO 3 radicals (Yang et al, 2011;Liu et al, 2012Liu et al, , 2015Wang et al, 2012Wang et al, , 2013 only considered the L-R mechanism. The heterogeneous reactivity of organic compounds with hydroxyl radicals was described by both L-H mechanism (Bagot et al, 2008;Vlasenko et al, 2008;Enami et al, 2014) and L-R mechanism (Socorro et al, 2016).…”

“…Some studies about heterogeneous NO 3 radicals oxidation of pesticides exist, in which kinetic data were obtained with pesticides suspended with azelaic acid as nucleation cores to form aerosols exposed to NO 3 radicals give second-order rate constants ranged between 10 -14 cm 3 molecule -1 s -1 and 10 -12 cm 3 molecule -1 s -1 Liu et al, 2012Liu et al, , 2015Wang et al, 2012Wang et al, , 2013. These values are higher than the second-order rate constants obtained in this study (about 10 -15 cm 3 molecule -1 s -1 ).…”

“…Major atmospheric oxidants are ozone (O 3 ), hydroxyl radicals (OH), and nitrate radicals (NO 3 ). Heterogeneous degradation by ozone and OH radicals was already studied for some pesticides (Borrás et al, 2015;Chen et al, 2016;Socorro et al, 2016;Mattei et al, 2018), but their degradation by nitrate radicals is poorly described (Yang et al, 2011;Liu et al, 2011Liu et al, , 2012Liu et al, , 2015Wang et al, 2012Wang et al, , 2013. Nitrate radicals are present during the night in concentration from a few ppt (Khan et al, 2008;Crowley et al, 2010) up to several hundreds of ppt (Atkinson et al, 1985;Asaf et al, 2010) and could, therefore, have a significant impact on the atmospheric half-life of pesticides.…”

“…Literature concerning the heterogeneous degradation of pesticides by nitrate radical is very scarce. A few studies (Yang et al, 2011;Liu et al, 2011Liu et al, , 2012Liu et al, , 2015Wang et al, 2012Wang et al, , 2013 relate the degradation of mainly organophosphorus pesticides according to degradation rates ranging between of 10 -14 cm 3 molecule -1 s -1 and 10 -12 cm 3 molecule -1 s -1 , which correspond to heterogeneous half-life regarding NO 3 radicals of a few hours. This suggests a significant degradation of pesticides by NO 3 radicals compared to other oxidants.…”

Reactivity of Semivolatile Organic Compounds with Hydroxyl Radicals, Nitrate Radicals, and Ozone in Indoor Air

“…The second-order reaction rate constants of gas-and particle-phase SVOCs with either OH, NO 3 , or ozone reported in previous studies were measured in a laboratory chamber [36] or an atmospheric environmental chamber [37] using the absolute rate method or the relative rate method [38]. Particle-phase SVOCs were experimentally created by adsorbing SVOCs on different types of particle substrates, e.g., silica [39], azelaic acid [40], and diesel soot [41]. In the present study, the available measured second-order rate constants of OH/SVOC, NO 3 /SVOC, and ozone/SVOC reactions in air were retrieved from the literature using the Google Scholar search engine.…”