The photochemical generation of hydrogen peroxide in natural waters

Abstract-Formation rates and steady-state concentrations of hydroxyl radical (• OH) in illuminated surface water samples collected in west-central Indiana that receive acidic mine drainage runoff are reported. Formation rates for• OH in samples were measured by the addition of 1 ϫ 10 Ϫ3 M benzene prior to illumination in order to effectively scavenge all of the • OH formed, thereby yielding phenol. The• OH formation rates were calculated from the measured phenol formation rates.

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“…2 2 2 2 a q Photochemical formation of H 2 O 2 has been observed in a variety of natural waters exposed to sunlight [19,20]. Once…”

Section: Hydroxyl Radical Formation and Reactionsmentioning

confidence: 99%

Formation of hydroxyl radical (·OH) in illuminated surface waters contaminated with acidic mine drainage

Allen

Lucas

Allen

1996

Enviro Toxic and Chemistry

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“…Photochemical reactions are also a common source of H 2 O 2 in terrestrial [31] and marine [32] aqueous environments. [33] The underlying mechanism is the photo-ionisation or photoexcitation of dissolved organic matter by sunlight, producing free electrons or excited states that can reduce dissolved oxygen to superoxide (Eqn 4, OM, organic matter).…”

Section: Iron In Naturementioning

confidence: 99%

Iron-catalysed oxidation and halogenation of organic matter in nature

et al. 2015

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Environmental context. Natural organohalogens produced in and released from soils are of utmost importance for ozone depletion in the stratosphere. Formation mechanisms of natural organohalogens are reviewed with particular attention to recent advances in biomimetic chemistry as well as in radical-based Fenton chemistry. Iron-catalysed oxidation in biotic and abiotic systems converts organic matter in nature to organohalogens.Abstract. Natural and anthropogenic organic matter is continuously transformed by abiotic and biotic processes in the biosphere. These reactions include partial and complete oxidation (mineralisation) or reduction of organic matter, depending on the redox milieu. Products of these transformations are, among others, volatile substances with atmospheric relevance, e.g. CO 2 , alkanes and organohalogens. Natural organohalogens, produced in and released from soils and salt surfaces, are of utmost importance for stratospheric (e.g. CH 3 Cl, CH 3 Br for ozone depletion) and tropospheric (e.g. Br 2 , BrCl, Cl 2 , HOCl, HOBr, ClNO 2 , BrNO 2 and BrONO 2 for the bromine explosion in polar, marine and continental boundary layers, and I 2 , CH 3 I, CH 2 I 2 for reactive iodine chemistry, leading to new particle formation) chemistry, and pose a hazard to terrestrial ecosystems (e.g. halogenated carbonic acids such as trichloroacetic acid). Mechanisms for the formation of volatile hydrocarbons and oxygenated as well as halogenated derivatives are reviewed with particular attention paid to recent advances in the field of mechanistic studies of relevant enzymes and biomimetic chemistry as well as radical-based processes.

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“…OPs fate in the environment is affected by transport, chemical, and biological processes, the rate of which are largely unknown. Direct and indirect photochemical processes are the methods involved in the photodegradation of pesticides in aquatic environment [22]. Direct absorption of sunlight by the pollutants is accompanied by chemical reactions in a process called direct photolysis, while the indirect photolysis is sometimes initiated through light absorption by natural substances.…”

Section: Hydrolysis Hydrolysis Hydrolysismentioning

confidence: 99%