Photochemical oxidants creation

Photochemical Oxidants Creation Potential. This is a measure of the potential to generate smog and is expressed relative to ethene. 

POCP = photochemical oxidant creation potential (kg ethylene eq) Resource use... 

Photochemical oxidants creation potential. Photochemical smog is caused by the degradation of VOCs and nitrogen and is expressed in kg of ethylene. 

Laser flash photolysis and discharge flow measurements of the reaction rates of OH with several VOC have been made in a project designed to provide data for the determination of the photochemical ozone creation potentials of the VOC. In related studies, the mechanisms of the atmospheric oxidation of a wide range of compounds have been developed. Finally, objective techniques for extensive mechanism reduction, first applied in combustion chemistry, have been applied to tropospheric mechanisms. 

Together with the rate coefficients of primary oxidant attack ( which correspond to the lifetime of the parent compound) NOCON factors may be used in atmospheric chemical - dynamic modelling to derive photochemical ozone creation potentials (POCP - values) for the individual hydrocarbons. POCP- values are expected to be the primary assessment factors in photochemical smog abatement strategies. 

Photochemical ozone creation Ground-level ozone, which has impacts on animal and plant life, is produced by reactions of hydrocarbons and nitrogen oxides to light ( summer smog )... 

If a sensitizer such as benzophenone is added to the polymer, sufficient oxidation can occur simply by exposure to ultraviolet light. In this photochemical treatment, creation of polymeric radicals by proton abstraction occurs readily with the formation of the highly resonance-stabilized diphenylhydroxymethyl radical. 

The non-methane organic compounds emitted from landfills contribute to photochemical smog creation. These compounds combine with nitrogen oxides present in the atmosphere to form the photochemical oxidants (e.g. ozone) (Cardelino Chameides, 2000). 

Thus, the main, long-lived intermediate formed in the atmospheric oxidation of benzaldehyde is nitrophenol. The oxidation involves two NO to NO2 conversions, but one of these NO2 species is then incorporated in the nitrophenol and so the route is inefficient at generating ozone. Furthermore, it leads to scavenging of NO in forming the nitrophenol. The net result is that benzaldehyde has a negative photochemical ozone creation potential, largely because of the NO c scavenging effect (Derwent et al., 1998). 

Paul continued to make major contributions to stratospheric chemistry. For example, he explained how nitric acid clouds cause the Antarctic ozone hole. At the same time, he also turned his attention to the troposphere, which is the air layer that connects with the biosphere and where weather and climate take place. The troposphere is also prone to air pollution, while it is cleaned by oxidation reactions. The self-cleaning capacity relies on the presence of reactive hydroxyl radicals that convert pollutant gases into more soluble compounds that are removed by rain. The primary formation of hydroxyl radicals in turn is from ozone. While most ozone is located in the stratosphere, protecting life on Earth against harmful ultraviolet radiation from the Sun, a small amount is needed in the troposphere to support the self-cleaning capacity. While previous theories had assumed that tropospheric ozone originates in the stratosphere, Paul discovered that much of it is actually chemically formed within the troposphere. The formation mechanism is similar to the creation of ozone pollution in photochemical smog . 

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