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1,2,4-Trioxolanes, known as secondary ozonides (SOZs), are key products of ozonolysis of biogenic terpenoids. Functionalized terpenoid-derived SOZs are readily taken up into atmospheric aerosols; however, their condensed-phase fates remain unknown. Here, we report the results of a time-dependent mass spectrometric investigation into the liquid-phase fates of C 10 and C 13 SOZs synthesized by ozonolysis of a C 10 monoterpene alcohol (α-terpineol) in water:acetone (1:1 = vol:vol) mixtures. Isomerization of Criegee intermediates and bimolecular reaction of Criegee intermediates with acetone produced C 10 and C 13 SOZs, respectively, which were detected as their Na + -adducts by positive-ion electrospray mass spectrometry. Use of CD 3 COCD 3 , D 2 O, and H 2 18 O solvents enabled identification of three types of C 13 SOZs (aldehyde, ketone, and lactol) and other products. These SOZs were surprisingly stable in water:acetone (1:1) mixtures at T = 298 K, with some persisting for at least a week. Theoretical calculations supported the high stability of the lactol-type C 13 SOZ formed from the aldehyde-type C 13 SOZ via intramolecular rearrangement. The present results suggest that terpenoid-derived SOZs can persist in atmospheric condensed phases, potentially until they are delivered to the epithelial lining fluid of the pulmonary alveoli via inhaled particulate matter, where they may exert hitherto unrecognized adverse health effects.

A detailed inventory was taken of evaporative emissions from parked gasoline vehicles in the Kanto region of Japan, 2015, based on the theoretical model to evaluate the amount of evaporative emissions. The inventory showed that evaporative emissions were high in metropolitan and urban areas because of the large populations in these areas and the high vehicle parking frequency. Using the new inventory, the sensitivity of evaporative emissions to the concentration of tropospheric ozone and secondary organic aerosol was evaluated using the chemical transport modeling solver, the community multiscale air quality modeling system (CMAQ), coupled with the weather research and forecasting (WRF) model. The calculation results showed that the evaporative emissions from permeation through fuel related parts were more significant in the generation of the tropospheric ozone than those from fuel tank venting. This was because the permeation emissions included a high proportion of high maximum incremental reactivity value components, such as aromatics. Neither of the evaporative emission types were significant secondary organic aerosol generators. Whole reduction of the evaporative emissions contributed an approximate 3 ppb decrease in tropospheric ozone in urban areas during the daytime. This information will contribute to the volatile organic compound (VOC) management strategy employed by governments worldwide.

The α-hydroxyalkyl-hydroperoxides [R-(H)C(-OH)(-OOH), α-HH] produced in the ozonolysis of unsaturated organic compounds may contribute to secondary organic aerosol (SOA) aging. α-HHs' inherent instability, however, hampers their detection and a positive assessment of their actual role. Here we report, for the first time, the rates and products of the decomposition of the α-HHs generated in the ozonolysis of atmospherically important monoterpenes α-pinene (α-P), d -limonene ( d -L), γ-terpinene (γ-Tn), and α-terpineol (α-Tp) in water/acetonitrile (W/AN) mixtures. We detect α-HHs and multifunctional decomposition products as chloride adducts by online electrospray ionization mass spectrometry. Experiments involving D 2 O and H 2 18 O, instead of H 2 16 O, and an OH-radical scavenger show that α-HHs decompose into gem -diols + H 2 O 2 rather than free radicals. α-HHs decay mono- or biexponentially depending on molecular structure and solvent composition. e-Fold times, τ 1/e , in water-rich solvent mixtures range from τ 1/e = 15-45 min for monoterpene-derived α-HHs to τ 1/e > 10 3 min for the α-Tp-derived α-HH. All τ 1/e 's dramatically increase in <20% (v/v) water. Decay rates of the α-Tp-derived α-HH in pure water increase at lower pH (2.3 ≤ pH ≤ 3.3). The hydroperoxides detected in day-old SOA samples may reflect their increased stability in water-poor media and/or the slow decomposition of α-HHs from functionalized terpenes.

Ozone readily reacts with olefins with the formation of more reactive Criegee intermediates (CIs). The transient CIs impact HO x cycles, and they play a role in new particle formation in the troposphere. Oxidation by O 3 occurs both in the gas-phase, in the liquid phase, and at air-water and air-aerosol interfaces. In light of the importance of O 3 in environmental and engineered chemical transformations, we have investigated the ozonolysis mechanisms of a triolefin C 15 -alcohol, nerolidol (Nero, a biogenic sesquiterpene), at the air-water interface in the presence of acetonitrile. Surface-sensitive pneumatic ionization mass spectrometric detection of α-hydroxy-hydroperoxides and functionalized carboxylates, generated by the hydration and isomerization of CIs, respectively, enables us to evaluate the relative reactivity of each C=C toward O 3 . In addition, we compare bulk-phase ozonolysis chemistry to similar reactions taking place at the air-water interface. Our experimental results show that O 3 reacts primarily with the (CH 3 ) 2 C=CH- and -(CH 3 )C=CH- moieties (>∼98%), while the O 3 attack on the terminal -HC=CH 2 site (<∼2%) is a minor pathway during both interfacial and bulk ozonolysis. The presence of functionalized-carboxylates on interfaces but not in bulk-phase reactions with O 3 indicates that the isomerization of the CIs is not hindered at the air-water interface due to the lower availability of water .

Jakarta Greater Area (JGA) has encountered recurrent challenges of air pollution, notably, high ozone levels. We investigate the trends of surface ozone (O3) changes from the air quality monitoring stations and resolve the contribution of meteorological drivers in urban Jakarta (2010–2019) and rural Bogor sites (2017–2019) using stepwise Multi Linear Regression. During 10 years of measurement, 41% of 1-h O3 concentrations exceeded Indonesia' s national threshold in Jakarta. In Bogor, 0.1% surpassed the threshold during 3 years of available data records. The monthly average of maximum daily 8-h average (MDA8) O3 anomalies exhibited a downward trend at Jakarta sites while increasing at the rural site of Bogor. Meteorological and anthropogenic drivers contribute 30% and 70%, respectively, to the interannual O3 anomalies in Jakarta. Ozone formation sensitivity with satellite demonstrates that a slight decrease in NO2 and an increase in HCHO contributed to declining O3 in Jakarta with 10 years average of HCHO to NO2 ratio (FNR) of 3.7. Conversely, O3 increases in rural areas with a higher FNR of 4.4, likely due to the contribution from the natural emission of O3 precursors and the influence of meteorological factors that magnify the concentration. [ABSTRACT FROM AUTHOR]

Ozone (O3) is a pollutant of concern in urban areas because of its effects on health, crops, ecosystems, and materials. Despite efforts to meet the Japanese air quality standard for O3 in the Kanto region, the attainment percentage is close to zero. Considering that O3 formation is sensitive to emissions of volatile organic compounds (VOC) and nitrogen oxides (NOx), this study evaluated a range of reductions in the emissions of both precursors using a regional air quality model (ADMER-PRO) and estimated their benefits measured as the economic change due to O3 concentration differences between scenarios. The simulation period was set during the 2016 O3 season. The results showed that O3 concentrations could be reduced using two approaches: significant reduction in VOC levels combined with minor NOx level changes or significant NOx emission reduction. Significant reduction in NOx levels was the most effective strategy for a generalized decrease in the O3 levels in the Kanto region, and the benefit analysis revealed that the most significant economic impacts could be achieved by adopting the latter approach. [ABSTRACT FROM AUTHOR]

Gaseous I2formation fromthe heterogeneous reactionof gaseous ozone with aqueous iodide in the presence of aqueous ferrousion (Fe2+) was investigated by electron impact ionizationmass spectrometry. Emission of gaseous I2increased asa function of the aqueous FeCl2concentration, and themaximum I2formation with Fe2+was about 10times more than without Fe2+. This enhancement can be explainedby the OH–scavenging by Fe3+formedfrom Fe2+ozonation to produce colloidal Fe(OH)3. This mechanism was confirmed by measurements of aqueous phase productsusing a UV–vis spectrometer and an electrospray ionizationmass spectrometer. We infer that such a pH-buffering effect may playthe key role in general halogen activations. [ABSTRACT FROM AUTHOR]