7/2/2023 0 Comments Reactivity of halogensPrecursor of OH in photooxidation chemistry. Those reactive halogensĪre potent oxidizers in addition to removing ozone, which is a normal With the observable consequence being ODEs. The fact that high reactive halogen levels were found to be present, Of these bromine-containing air samples was not understood at the Levels in the Arctic had been noted earlier, but the sources and chemistry 13 The presence of anomalously high particulate and gas-phase bromine Implicated by Barrie and co-workers in 1988. Were discovered in the troposphere in the midlate 1980s, 11, 12 and chemical loss of ozone by halogens, bromine in this case, was Implicated was the high Arctic, where ozone depletion episodes (ODEs) The first region of the troposphere where halogen chemistry was Particulate ionic composition were highly influenced by photochemical That was not the only effect and that these observations of marine Of the weaker acid HCl by deposition of stronger acids such as H 2SO 4 and HNO 3, but later work would show The chloride observations were consistent with displacement Was known that marine aerosol particles were depleted in chlorideĪnd bromide and strongly enriched in iodide as compared to seawater Noted that “.the major pathways of nature’s halogenĬycles are seen only in general terms key transformation processesĪnd rates are not known with any accuracy.” At this time, it Information on the measurements of halogens in the troposphere, but In Cicerone’sġ981 10 review article, he compiled excellent Tropospheric chemistry was not yet discovered. However, the realization that halogens played a role in Sherwood Rowland for their work on stratospheric ozone depletionĬhemistry. Of the 1995 Nobel Prize in Chemistry to Paul Crutzen, Mario MolinaĪnd F. Literature considering how halogen radicals, such as chlorine atoms,Ĭould deplete ozone aloft. In 1974, there was a flurry of activity in the stratospheric chemistry 5, 6 Reactive halogens, on the other hand, generally destroy ozone inĬatalytic cycles, altering the oxidation capacity of the atmosphere. Sunlight, and hydrocarbons produce most tropospheric ozone. Nm region, and cycles involving odd hydrogen radicals (known as HO x = OH + HO 2) and nitrogen oxides Of OH arises from photolysis of ozone in the ∼300–320 Both OH and reactive halogen photooxidation chemistry Interplay between OH-driven and reactive-halogen-driven photooxidation In many regions throughout the troposphere, and there is an important We will show in this Review, reactive halogens have significant influences Removes natural and anthropogenic pollutants primarily through OH-driven Of these compounds, 1− 3 leading to the picture that the Earth’s atmosphere Through studies of carbon monoxide and methane oxidation in the earlyġ970s, it was realized that OH radicals largely controlled the lifetime To be a critical species for tropospheric photooxidation chemistry. Are important oxidizers, the hydroxyl radical (OH) was first realized
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