Free-Radical Oxidants in Natural Waters

Mill, Theodore; Hendry, Dale G.; Richardson, H. Wayne

doi:10.1126/science.207.4433.886

Cited by 227 publications

(115 citation statements)

References 7 publications

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“…Hydrogen peroxide (H202) appears to be ubiquitous in the hydrosphere and has been found in rainwater, seawater and freshwater (Daum 1985;Mill, Hendry and Richardson 1980). In the presence of light, H20 2 can produce .OH radicals (Beltran, Ovejero and Acedo 1993) which can attack the environmental chemicals.…”

Section: Introductionmentioning

confidence: 99%

Photodegradation of phenanthrene in the presence of humic substances and hydrogen peroxide

Wangl

Yediler²,

et al. 1995

Chemosphere

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The photodegradation of phenanthrene in water was investigated for a variety of reaction conditions employing various fulvic acids (FAs) as photosensitizers and hydrogen peroxide as oxidant. All experiments were conducted by using artificial sunlight from Suntest apparatus (Hanau, Germany) as light source. The relative rates of phenanthrene photodegradation for the different experimental conditions were computed. Fulvic acids of different origins influenced the rate of sunlight-induced photodegradation of phenanthrene in different ways. Hydrogen peroxide vigorously enhanced the photodegradation rate of phenanthrene. The photoproducts identified were oxygenated products of aromatic ring, such as 9,10,-phenanthrenquinone, a group of hydroxyphenanthrene with hydroxyl at different position (1,3,4, and 9), 2,2'-biphenyldicarbonic acid, 2,2'-biphenyldialdehyde and 2-phenylbenzaldehyde. It can be consumed that the phenanthrene photodegraded via free radical mechanism.

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Section: Introductionmentioning

confidence: 99%

Photodegradation of phenanthrene in the presence of humic substances and hydrogen peroxide

Wangl

Yediler²,

et al. 1995

Chemosphere

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“…The interaction between ultraviolet (UV) radiation and dissolved organic carbon (DOC) can result in the formation of chemically reactive and biologically toxic compounds, including hydroxyl-and alkyl-peroxyl radicals (Mill et al 1980), superoxides, and hydrogen peroxide (H 2 O 2 ) (Cooper et al 1988). H 2 O 2 is long-lived compared with other oxidants and radicals and is measurable by simple methods, making it a useful marker of DOC photolysis and of the photochemical production of oxidizing agents (Cooper et al 1989b).…”

Section: Introductionmentioning

confidence: 99%

Hydrogen peroxide distribution, production, and decay in boreal lakes

Häkkinen¹,

Anesio²,

Granéli³

2004

Can. J. Fish. Aquat. Sci.

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Abstract:The distribution, production, and decay of hydrogen peroxide (H 2 O 2 ) were studied in 10 boreal lakes of differing physical-chemical characteristics. Diurnal and vertical fluctuations in H 2 O 2 concentration were followed in the lakes by sampling at six depths three times per day. In addition, incubations of water filtered through 0.2-µm mesh were made under artificial irradiation to study the abiotic production and decay of H 2 O 2 . H 2 O 2 concentrations after 8 h of artificial irradiation were significantly correlated with neither absorption coefficients at 320 nm nor with dissolved organic carbon (DOC) concentrations. However, H 2 O 2 concentration increased rapidly with DOC concentration among lakes with DOC concentrations below 10 mg·L -1 . The H 2 O 2 concentration after exposure to ultraviolet radiation was positively related to the half-life of H 2 O 2 , which in turn was negatively correlated with iron and manganese concentrations (r 2 = 0.68 and 0.70, respectively). In situ H 2 O 2 concentrations at the surface of the water column ranged between 30 and 1041 nmol·L -1 and were largely determined by the decay rates of H 2 O 2 and the mixing depth of the water column.

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“…It has been proposed Mill, 1980;Mill et al, 1980) that an additional source of hydroxyl radical is through the photolysis of colored or chromophoric dissolved organic matter (CDOM) (10). Although the precise mechanism by which hydroxyl radical is formed is currently unknown, one possible mechanism may involve the follwing steps ).…”

Section: Introductionmentioning

confidence: 99%

Photophysics and photochemistry of natural waters with emphasis on radical probe development and application

Herbelin¹

1994

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The work presented here consists of a literature review and calculations to estimate the importance of photochemistry to carbon cycling in the oceans, followed by a photophysical study of a series of stable nitroxide radical probes that have been used for the quantitative detection of individual carbon-centered radicals and reducing species in natural waters. Two appendices follow. The first contains preliminary experiments utilizing one of the nitroxide probes in an investigation of hydroxyl radical production rates and steadystate concentrations in seawater. The second consists of an investigation of the singlet lifetimes of humic acids (HA), in order to aid in understanding their photochemical cycling and influence on other compounds.The impact of photochemical reactions on global oceanic carbon cycling was calculated from literature values. The results indicate that between 1 and 13% of all dissolved organic carbon in the oceans is oxidized photochemically. This is a significant flux term, much larger than that of riverine input for example.A photophysical study of nitroxide radical probes was undertaken. For all of the compounds studied, steady-state absorption and fluorescence spectra were identical to those of the parent fluorophores. A decrease in fluorescence lifetime and quantum yield of tens-to hundreds-fold was observed for the paramagnetic compounds relative to their diamagnetic counterparts. Very rapid fluorescence quenching rates (3 to 80 x 1010 s-1 ) were calculated for the fluorescamine moiety of the paramagnetic nitroxide compounds in a variety of solvents. Calculated energy minimized geometries were very similar for all compounds which implies that geometric differences are not responsible for the variations found in fluorescence lifetimes and quantum yields between compounds. Calculated Firster and Dexter overlap integrals do not support deexcitation by these mechanisms. Time-resolved absorption measurements resulted in no evidence for transient species due to either intersystem crossing to the triplet state or charge transfer. Of the mechanisms considered, direct internal conversion to the ground state, is most likely given our results.An investigation of the utility of 3-(aminomethyl)-2,2,5,5-tetramethyl-1-pyrrolidinyloxy free radical (3-amp) for detection and quantification of hydroxyl radicals in natural waters found that the addition of primary probe compounds resulted in the generation of secondary carbon-centered radicals that were successfully trapped by 3-amp. Competition kinetics experiments with dimethyl sulfoxide resulted in a natural scavenger rate constant that matched previous literature results for coastal seawater. As expected, the addition of formate resulted in decreases, and the addition of nitrite in increases, in the hydroxyl radical trapping rate by this method. The resulting quantum yield values were about an order of magnitude higher than previous literature results. However, probablyI IYIIIIYYI Wilkl 4 due to the use of different latitudes at which to estimat...

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Free-Radical Oxidants in Natural Waters

Cited by 227 publications

References 7 publications

Photodegradation of phenanthrene in the presence of humic substances and hydrogen peroxide

Photodegradation of phenanthrene in the presence of humic substances and hydrogen peroxide

Hydrogen peroxide distribution, production, and decay in boreal lakes

Photophysics and photochemistry of natural waters with emphasis on radical probe development and application

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