A numerical experiment on the relative importance of H2O2 O3 in aqueous conversion of SO2 to SO42-

Fung, C.S.; Misra, P. K.; Bloxam, R.; Wong, S.

doi:10.1016/0960-1686(91)90312-u

Cited by 51 publications

(22 citation statements)

References 7 publications

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“…The latter may be oxidized by hydrogen peroxide, ozone, organic peroxides, or catalytic oxygen reactions to bisulphate and sulphate ions, the ionic equilibrium products of sulphuric acid dissociation (Hermann et al, 2000(Hermann et al, , 2005. H 2 O 2 is believed to be the dominant aqueous-phase oxidant of HSO − 3 , but the strongly pH-dependent oxidation by O 3 becomes more important as pH increases or when H 2 O 2 has been depleted (e.g., Fung et al, 1991). The relative contribution of these two oxidants to aqueous-phase sulphate formation is therefore influenced by NH 3 levels.…”

Section: Introductionmentioning

confidence: 99%

Modelling the impacts of ammonia emissions reductions on North American air quality

et al. 2009

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Abstract.A unified regional air-quality modelling system (AURAMS) was used to investigate the effects of reductions in ammonia emissions on regional air quality, with a focus on particulate-matter formation. Three simulations of one-year duration were performed for a North American domain: (1) a base-case simulation using 2002 Canadian and US national emissions inventories augmented by a more detailed Canadian emissions inventory for agricultural ammonia; (2) a 30% North-American-wide reduction in agricultural ammonia emissions; and (3) a 50% reduction in Canadian beef-cattle ammonia emissions. The simulations show that a 30% continent-wide reduction in agricultural ammonia emissions lead to reductions in median hourly PM 2.5 mass of <1 µg m −3 on an annual basis. The atmospheric response to these emission reductions displays marked seasonal variations, and on even shorter time scales, the impacts of the emissions reductions are highly episodic: 95th-percentile hourly PM 2.5 mass decreases can be up to a factor of six larger than the median values.A key finding of the modelling work is the linkage between gas and aqueous chemistry and transport; reductions in ammonia emissions affect gaseous ammonia concentrations close to the emissions site, but substantial impacts on particulate matter and atmospheric deposition often occur at considerable distances downwind, with particle nitrate being the main vector of ammonia/um transport. Ammonia emissions reductions therefore have trans-boundary consequences downwind. Calculations of critical-load exceedances for sensitive ecosystems in Canada suggest that ammonia emission reductions will have a minimal impact on Correspondence to: P. A. Makar (paul.makar@ec.gc.ca) current ecosystem acidification within Canada, but may have a substantial impact on future ecosystem acidification. The 50% Canadian beef-cattle ammonia emissions reduction scenario was used to examine model sensitivity to uncertainties in the new Canadian agricultural ammonia emissions inventory, and the simulation results suggest that further work is needed to improve the emissions inventory for this particular sector. It should be noted that the model in its current form neglects coarse mode base cation chemistry, so the predicted effects of ammonia emissions reductions shown here should be considered upper limits.

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Section: Introductionmentioning

confidence: 99%

Modelling the impacts of ammonia emissions reductions on North American air quality

et al. 2009

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“…1 for the domain used here), and a Gal-Chen vertical coordinate with variable resolution is used. The CRCM vertical levels are staggered on terrain-following Gal-Chen coordinates (Gal- Chen and Sommerville, 1975) and increase in thickness from approximately 60 m at the surface to 3.5 km near the model lid at 29 km. All vertical levels of the CRCM fall within the vertical domain of the driving data provided by the CGCM.…”

Section: Crcmmentioning

confidence: 99%

“…This is followed by the Canadian Aerosol Module (Gong et al, 2003a, b) which resolves aerosol size and chemical speciation using 12 bins (sectional approach) for 9 species (sulphate, nitrate, ammonium, secondary organic aerosol, primary organic aerosol, elemental carbon, sea-salt, crustal material, and aerosol water). Processes treated by the aerosol module include particle microphysics (condensation of sulphate and secondary organic condensable mass, coagulation, nucleation of sulphate aerosols), aqueous-phase chemistry (ADOM aqueous phase mechanism, Venkatram et al, 1988;Fung et al, 1991;using solver of Young and Boris, 1977, for integration), wet deposition (precipitation production and flux from both resolved and sub-grid scales are included in the wet deposition calculation; Gong et al, 2006), inorganic heterogeneous chemistry of sulphate, nitrate and ammonium (HETV solver, Makar et al, 2003), sea-salt emissions (Gong et al, 2003a), and particle settling and deposition (Gong et al, 2003a;Zhang et al, 2001). Sub-grid-scale convective tracer mixing and transport is not included in AURAMS though these processes are resolved when AURAMS is used at high resolution.…”

Section: Auramsmentioning

confidence: 99%

Projections of mid-century summer air-quality for North America: effects of changes in climate and precursor emissions

2012

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Abstract. Ten year simulations of North American current and future air-quality were carried out using a regional airquality model driven by a regional climate model, in turn driven by a general circulation model. Three separate summer scenarios were performed: a scenario representing the years 1997 to 2006, and two SRES A2 climate scenarios for the years 2041 to 2050. The first future climate scenario makes use of 2002 anthropogenic precursor emissions, and the second applied emissions scaling factors derived from the IPCC Representative Concentration Pathway 6 (RCP 6) scenario to estimate emissions for 2050 from existing 2020 projections. Ten-year averages of ozone and PM 2.5 at North American monitoring network stations were used to evaluate the model's current chemical climatology. The model was found to have a similar performance for ozone as when driven by an operational weather forecast model. The PM 2.5 predictions had larger negative biases, likely resulting from the absence of rainwater evaporation, and from sub-regional negative biases in the surface temperature fields, in the version of the climate model used here.The differences between the two future climate simulations and the current climate simulation were used to predict the changes to air-quality that might be expected in a future warmer climate, if anthropogenic precursor emissions remain constant at their current levels, versus if the RCP 6 emissions controls were adopted. Metrics of concentration, human health, and ecosystem damage were compared for the simulations. The scenario with future climate and current anthropogenic emissions resulted in worse air-quality than for current conditions -that is, the effect of climate-change alone, all other factors being similar, would be a worsening of air-quality. These effects are spatially inhomogeneous, with the magnitude and sign of the changes varying with region. The scenario with future climate and RCP 6 emissions for 2050 resulted in an improved air-quality, with decreases in key pollutant concentrations, in acute human mortality associated with air-pollution, and in sulphur and ozone deposition to the ecosystem. The positive outcomes of the RCP 6 emissions reductions were found to be of greater magnitude than the negative outcomes of climate change alone. The RCP 6 scenario however resulted in an increase in the deposition of nitrogen, as a result of increased ammonia emissions expected in that scenario, compared to current ammonia emissions levels.The results of the study raise the possibility that simultaneous reductions of greenhouse gases and air pollution precursors may further reduce air pollution levels, with the added benefits of an immediate reduction in the impacts of air pollution on human and ecosystem health. Further scenarios to investigate this possibility are therefore recommended.

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“…These reactive species play significant roles in atmospheric processes, such as acid precipitation, cycling of HO x radicals, and formation of secondary organic aerosol (SOA). H 2 O 2 is considered to be the most important oxidant for the conversion of S (IV) to sulfuric acid and secondary sulfate in cloud, fog and rain water at pH<5, thus contributing significantly to the acidification of clouds and rain (Penkett et al, 1979;Calvert et al, 1985;Fung et al, 1991;Pena et al, 2001). Organic peroxides such as MHP, HMHP, and PAA are able to oxidize SO 2 , but only when H 2 O 2 is limited (Lind et al, 1987;Zhou and Lee, 1992).…”

Section: Introductionmentioning

confidence: 99%

Atmospheric hydrogen peroxide and organic hydroperoxides during PRIDE-PRD'06, China: their concentration, formation mechanism and contribution to secondary aerosols

et al. 2008

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Abstract. Atmospheric hydrogen peroxide (H 2 O 2 ) and organic hydroperoxides were measured from 18 to 30 July in 2006 during the PRIDE-PRD'06 campaign at Backgarden, a rural site located 48 km north of Guangzhou, a mega-city in southern China. A ground-based instrument was used as a scrubbing coil collector to sample ambient air, followed by on-site analysis by high-performance liquid chromatography (HPLC) coupled with post-column derivatization and fluorescence detection. The H 2 O 2 mixing ratio over the 13 days ranged from below the detection limit to a maximum of 4.6 ppbv, with a mean (and standard deviation) of (1.26±1.24) ppbv during the daytime (08:00-20:00 LT). Methyl hydroperoxide (MHP), with a maximum of 0.8 ppbv and a mean (and standard deviation) of (0.28±0.10) ppbv during the daytime, was the dominant organic hydroperoxide. Other organic peroxides, including bis-hydroxymethyl hydroperoxide (BHMP), peroxyacetic acid (PAA), hydroxymethyl hydroperoxide (HMHP), 1-hydroxy-ethyl hydroperoxide (1-HEHP) and ethyl hydroperoxide (EHP), were detected occasionally. The concentration of H 2 O 2 exhibited a pronounced diurnal variation on sunny days, with a peak mixing ratio in the afternoon (12:00-18:00 LT), but lacked an explicit diurnal cycle on cloudy days. Sometimes a second peak mixing ratio of H 2 O 2 was observed during the evening, suggesting that H 2 O 2 was produced by the ozonolysis of Correspondence to: Z. M. Chen (zmchen@pku.edu.cn) alkenes. The diurnal variation profile of MHP was, in general, consistent with that of H 2 O 2 . The estimation indicated that in the morning the H 2 O 2 detected was formed mostly through local photochemical activity, with the rest probably attributable to vertical transport. It is notable that relatively high levels of H 2 O 2 and MHP were found in polluted air. The unexpectedly high level of HO 2 radicals detected in this region can account for the production of hydroperoxides, while the moderate level of NO x suppressed the formation of hydroperoxides. High concentrations of hydroperoxides were detected in samples of rainwater collected in a heavy shower on 25 July when a typhoon passed through, indicating that a considerable mixing ratio of hydroperoxides, particularly MHP, resided above the boundary layer, which might be transported on a regional scale and further influence the redistribution of HO x and RO x radicals. It was found that hydroperoxides, in particular H 2 O 2 , play an important role in the formation of secondary sulfate in the aerosol phase, where the heterogeneous reaction might contribute substantially. A negative correlation between hydroperoxides and water-soluble organic compounds (WSOC), a considerable fraction of the secondary organic aerosol (SOA), was observed, possibly providing field evidence for the importance of hydroperoxides in the formation of SOA found in previous laboratory studies. We suggest that hydroperoxides act as an important link between sulfate and organic aerosols, which needs further study and should be considered in cu...

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A numerical experiment on the relative importance of H2O2 O3 in aqueous conversion of SO2 to SO42-

Cited by 51 publications

References 7 publications

Modelling the impacts of ammonia emissions reductions on North American air quality

Modelling the impacts of ammonia emissions reductions on North American air quality

Projections of mid-century summer air-quality for North America: effects of changes in climate and precursor emissions

Atmospheric hydrogen peroxide and organic hydroperoxides during PRIDE-PRD'06, China: their concentration, formation mechanism and contribution to secondary aerosols

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