Evaluation of primary photoproduct quantum yields in fulvic acid

Bruccoleri, Aldo G.; Pant, Bhuvan C.; Sharma, Dinkar; Langford, Cooper H.

doi:10.1021/es00042a011

Cited by 66 publications

(74 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because the triplet energy of TMP is 332 kJ/mol (Canonica and Hoigne 1995;Canonica et al 1995) and the triplet energy of DOM is on average 170-180 kJ/mol (Bruccoleri et al 1993), a pathway involving energy transfer is very unlikely. For energy transfer to be favorable, the triplet energy of the excited state sensitizer (i.e., DOM) must be higher than the triplet energy of the probe to which it is transferring the energy.…”

Section: Discussionmentioning

confidence: 99%

Evaluating the triplet state photoreactivity of dissolved organic matter isolated by chromatography and ultrafiltration using an alkylphenol probe molecule

Cawley

Hakala

Chin

2009

Limnology & Ocean Methods

View full text Add to dashboard Cite

The triplet state photochemistry of dissolved organic matter (DOM) isolated by XAD and C-18 chromatography and tangential flow ultrafiltration (TFUF) was investigated using 2,4,6 trimethylphenol (TMP) as a molecular probe. Water samples were taken from an Arctic seep adjacent the Oksrukuyik River (OKS) on the north slope of Alaska, USA, where DOM is derived primarily from allochthonous material and from a eutrophic midlatitude wetland, Old Woman Creek (OWC), in northern Ohio, USA, where the DOM is formed from both allochthonous and autochthonous precursors. DOM-mediated TMP photolysis occurred for all samples, but was significantly faster in the OWC isolates. The method used to isolate DOM also influenced TMP photoreactivity, whereby the C-18 and XAD isolated material were typically more reactive than ultrafiltered DOM. Analysis of the isolates by spectroscopy revealed that the materials isolated by chromatography were relatively enriched in aromatic constituents, while the TFUF fraction had the lowest aromaticity based on molar absorptivity at 280 nm. The fluorescence index values revealed differences between OKS and OWC, but no discernable trends were observed among isolates. This study shows that both the manner in which DOM is isolated and the composition of its precursors will influence its triplet state photoreactivity.

show abstract

Section: Discussionmentioning

confidence: 99%

Evaluating the triplet state photoreactivity of dissolved organic matter isolated by chromatography and ultrafiltration using an alkylphenol probe molecule

Cawley

Hakala

Chin

2009

Limnology & Ocean Methods

View full text Add to dashboard Cite

show abstract

“…The deactivation of an electronically excited state of CDOM then occurs via, e.g., ionization of CDOM to produce hydrated electrons (e À aq ) (Blough and Zepp, 1995 and refs. cited therein;Bruccoleri et al, 1993;Wang et al, 2007b;Zepp et al, 1987):…”

Section: Direct Photochemical Transformations Of Cdommentioning

confidence: 99%

“…The organic radical, which may be relatively longlived (Paul et al, 2006), can add molecular oxygen to form a peroxy radical cation (Bruccoleri et al, 1993), Aquat. Sci.…”

Section: Direct Photochemical Transformations Of Cdommentioning

confidence: 99%

Chemical characterization of dissolved organic matter (DOM): A prerequisite for understanding UV-induced changes of DOM absorption properties and bioavailability

2009

View full text Add to dashboard Cite

Abstract. UV-induced transformations of colored dissolved organic matter (CDOM, which is part of dissolved organic matter, DOM) affect CDOM absorption properties resulting in the loss of color (referred to as photobleaching). CDOM photobleaching increases the penetration depths of the damaging UV-B radiation into water bodies and strongly depends on the wavelength of solar radiation and on the pH of aquatic systems. UV-induced transformations also affect DOM availability to bacterioplankton, often enhancing the bioavailability of terrigenous DOM and in turn microbial respiration. The combination of UV-induced enhancement of DOM bioavailability and increased export of terrigeneous DOM into estuaries and coastal waters due to climaterelated changes in continental hydrology could result in a UV-mediated positive feedback of CO 2 accumulation in the atmosphere.The extent and type of CDOM photobleaching and of UV-induced changes in DOM bioavailability depend on (C)DOM chemical composition, which in turn undergoes drastic changes upon UV-induced transformations. Therefore, the chemical characterization of (C)DOM is key for rationalizing UV-induced transformations. In the second section (after the "Introduction"), we review important methods for the elucidation of the chemical composition of (C)DOM. However, this article is not intended to be comprehensive regarding (C)DOM chemical characterization. An important purpose is to provide photochemical bases for the understanding of UV-induced changes of (C)DOM absorption properties and bioavailability (mainly discussed in the sections "Pathways of DOM phototransformations" and "UV-induced changes of the absorption properties of CDOM").

show abstract

“…This is similar to the results obtained by Ž . Bruccoleri et al 1993 for Laurentian fulvic acids, where they found that photoionization was not sensitive to molecular mass. We hypothesize that the larger mass material is more likely to stabilize a free radical, increasing the lifetime and allowing detection by EPR.…”

Section: Photophysical Characteristicsmentioning

confidence: 99%

Photogeneration of singlet oxygen and free radicals in dissolved organic matter isolated from the Mississippi and Atchafalaya River plumes

et al. 2000

View full text Add to dashboard Cite

Ž. The photoreactivity to UV light of ultrafiltered dissolved organic matter DOM collected during cruises along salinity transects in the Mississippi and Atchafalaya River plumes was examined by measuring photogenerated free radicals and Ž 1 . singlet molecular oxygen O photosensitization. Singlet oxygen was detected by its infrared phosphorescence at 1270 nm 2 using both steady-state and time-resolved techniques. The 1 O quantum yields were corrected for self-quenching of 1 O by 2 2 Ž . the DOM substrates. Photogenerated free radicals were monitored by electron paramagnetic resonance EPR . Two size fractions of the dissolved organic matter were examined: material retained with a 3 kDa cut-off filter and material retained with a 1 kDa cut-off filter. The highest 1 O quantum yields were found in the lower molecular mass material. There was 2 little change in the 1 O quantum yields with increasing salinity, indicating that the photosensitizing ability of the estuarine 2 DOM does not decrease as terrestrial DOM is transported to sea and mixes with marine DOM. In contrast to 1 O formation, 2 the steady-state levels of photoproduced free radicals did not significantly differ between high and low molecular mass DOM, and the levels were substantially higher in riverine DOM than along plume salinity transects. This rapid transition in free radical level suggests that terrestrially-derived DOM experiences significant changes in this aspect of its photoreactivity Ž . in low -10 ppt salinity waters. Published by Elsevier Science B.V.

show abstract

Evaluation of primary photoproduct quantum yields in fulvic acid

Cited by 66 publications

References 12 publications

Evaluating the triplet state photoreactivity of dissolved organic matter isolated by chromatography and ultrafiltration using an alkylphenol probe molecule

Evaluating the triplet state photoreactivity of dissolved organic matter isolated by chromatography and ultrafiltration using an alkylphenol probe molecule

Chemical characterization of dissolved organic matter (DOM): A prerequisite for understanding UV-induced changes of DOM absorption properties and bioavailability

Photogeneration of singlet oxygen and free radicals in dissolved organic matter isolated from the Mississippi and Atchafalaya River plumes

Contact Info

Product

Resources

About