Light-induced alteration of the photophysical properties of dissolved organic matter in seawater Part I. Photoreversible properties of natural water fluorescence

Kouassi, Aka Marcel; Zika, Rod G.

doi:10.1016/0077-7579(90)90031-b

Cited by 46 publications

(30 citation statements)

References 19 publications

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“…A recovery of fluorescence after incubation under visible light alone was observed in lakes Violon and Ours. This recovery of DOCF could be related to the oxidative regeneration of DOC from particulate carbon and consequent formation of fluorescent materials (Kouassi andZika, 1990). 1922 E. Garcia, M. Amyot, and P. A. Ariya We calculated the fraction of total Hg that could be reduced in surface waters during the period of the day before the plateau in DGM was reached (when oxidation is less important than reduction).…”

Section: Effects Of Different Wavelengths On Losses In Docf and On Dgmentioning

confidence: 98%

Relationship between DOC photochemistry and mercury redox transformations in temperate lakes and wetlands

Garcia

Amyot

Ariya

2005

Geochimica et Cosmochimica Acta

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We compared diurnal variations in dissolved gaseous mercury (DGM) concentration and in losses of dissolved organic carbon fluorescence (DOCF) in four boreal Canadian Shield lakes, in one beaver pond, and in filtered and unfiltered water from a wetland in Lake St. Pierre, a fluvial lake of the St. Lawrence River. These systems were chosen to represent a spectrum of DOC. We also determined the contribution of UVB, UVA and visible light on DGM photo-induced production in the four lakes. Our results showed a strong relationship between DGM concentrations and light intensity and between DGM production and losses in DOCF, in all study sites. We also observed higher rates of DGM formation and of DOCF bleaching in the presence of UV radiation. Under UVB light, production of DGM was higher in clear lakes than in the humic ones. Inversely, in the UVA range, DGM production tended to be higher in humic lakes. We suggest that DOCF bleaching can be used as a proxy for the rate of formation of reactive species that may alter the redox state of mercury in surface waters. We also have indications that DGM production is more important in clear than in humic waters.

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Section: Effects Of Different Wavelengths On Losses In Docf and On Dgmentioning

confidence: 98%

Relationship between DOC photochemistry and mercury redox transformations in temperate lakes and wetlands

Garcia

Amyot

Ariya

2005

Geochimica et Cosmochimica Acta

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“…Fluorescent CDOM (FDOM) is also highly photolabile (Chen and Bada, 1992;Kouassi and Zika, 1990), with average percentage fluorescence losses exceeding both DOC and CDOM absorbance photobleaching . Thus, using the definitions applied here, the FDOM fraction represents the most photolabile DOM component.…”

Section: Dom Photolability Spectrum and Fate Of Terrestrial Dom Imentioning

confidence: 99%

Marine Photochemistry of Organic Matter

Mopper

Kieber

Stubbins

2015

Biogeochemistry of Marine Dissolved Organic Matter

140

134

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“…Since in absorbance processes of dissolved organic matter it is not possible to define an exact quantum yield, because the molar extinction coefficient is not known, we have followed the approach developed by Zika and coworkers cited by Plane et al, 1987, andKouassi et al, 1990. This approach involved defining an apparent monochromatic quantum yield C A , for the overall production process C x = 4>el = fc/2.303/ where k = the photolysis rate constant (s" 1 ); e = the molar extinction coefficient (dm 3 mol" ' cm~ *); / = the cell pathlength (cm); / = the intensity of the incident light (einstein dm" 3 sec" 1 ) calculated from the data of the potassium ferrioxalate as chemical actinometer.…”

Section: Computation Of the Rates Of The Absorbance Processesmentioning

confidence: 99%

Light‐induced destruction of the absorbance property of dissolved organic matter in seawater

Kouassi

Zika

1992

Toxicological & Environmental Chemistry

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The absorption spectra of marine humic substances decrease when they are exposed to a known intensity of monochromatic light at various wavelengths or to a polychromatic source such as sunlight. The results of studies of photochemical bleaching of absorption of marine humic substances are presented and compared to the characteristics of total dissolved organic matter to assess the contribution made by the humic fractions. From the absorbance and apparent quantum efficiency data at specific wavelength and the solar fluxes, a model calculation was used to determine the rates of the change of the photoprocess in the ocean. These parameters were determined for the photochemical degradation of Biscayne Bay (Florida, USA) seawater and humic substances collected in the Gulf of Mexico.

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Light-induced alteration of the photophysical properties of dissolved organic matter in seawater Part I. Photoreversible properties of natural water fluorescence

Cited by 46 publications

References 19 publications

Relationship between DOC photochemistry and mercury redox transformations in temperate lakes and wetlands

Relationship between DOC photochemistry and mercury redox transformations in temperate lakes and wetlands

Marine Photochemistry of Organic Matter

Light‐induced destruction of the absorbance property of dissolved organic matter in seawater

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