Probing the oxidation–reduction properties of terrestrially and microbially derived dissolved organic matter

Fimmen, Ryan L.; Cory, Rose M.; Chin, Yu Ping; Trouts, Tamara D.; McKnight, Diane M.

doi:10.1016/j.gca.2007.04.009

Cited by 147 publications

(153 citation statements)

References 41 publications

(72 reference statements)

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“…The combination of pyrolytic or chemolytic techniques with GC/MS was a major breakthrough in the analysis of DOM. One of the chemolytic reagents used in combination with GC/MS is tetramethyl ammonium hydroxide (TMAH) (Fimmen et al, 2007;Frazier et al, 2005;Hatcher and Clifford, 1994;Wetzel et al, 1995;Zang et al, 2000). Another chemolytic reagent, which was implemented by John I.…”

Section: Bulk Characterization Of Dommentioning

confidence: 99%

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

2009

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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").

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Section: Bulk Characterization Of Dommentioning

confidence: 99%

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

2009

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“…Humic substances referred to as "Pony Lake" humic substances are fulvic acids that originated from a eutrophic pond in Antarctica where organic matter is derived exclusively from microbes, is highly aliphatic, and does not contain lignin (reference no. 1R109F) (18). We also performed experiments with Suwannee River humic substances (fulvic acid, humic acid, and Suwannee natural organic matter fractions).…”

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confidence: 99%

Rhodobacter capsulatus Catalyzes Light-Dependent Fe(II) Oxidation under Anaerobic Conditions as a Potential Detoxification Mechanism

Poulain

Newman

2009

Appl Environ Microbiol

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Diverse bacteria are known to oxidize millimolar concentrations of ferrous iron [Fe(II)] under anaerobic conditions, both phototrophically and chemotrophically. Yet whether they can do this under conditions that are relevant to natural systems is understood less well. In this study, we tested how light, Fe(II) speciation, pH, and salinity affected the rate of Fe(II) oxidation by Rhodobacter capsulatus SB1003. Although R. capsulatus cannot grow photoautotrophically on Fe(II), it oxidizes Fe(II) at rates comparable to those of bacteria that do grow photoautotrophically on Fe(II) as soon as it is exposed to light, provided it has a functional photosystem. Chelation of Fe(II) by diverse organic ligands promotes Fe(II) oxidation, and as the pH increases, so does the oxidation rate, except in the presence of nitrilotriacetate; nonchelated forms of Fe(II) are also more rapidly oxidized at higher pH. Salt concentrations typical of marine environments inhibit Fe(II) oxidation. When growing photoheterotrophically on humic substances, R. capsulatus is highly sensitive to low concentrations of Fe(II); it is inhibited in the presence of concentrations as low as 5 M. The product of Fe(II) oxidation, ferric iron, does not hamper growth under these conditions. When other parameters, such as pH or the presence of chelators, are adjusted to promote Fe(II) oxidation, the growth inhibition effect of Fe(II) is alleviated. Together, these results suggest that Fe(II) is toxic to R. capsulatus growing under strictly anaerobic conditions and that Fe(II) oxidation alleviates this toxicity.

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“…They play an important role in reducing Fe(III) to the more reactive Fe(II). For this to happen, HS can be in an oxidized or in a reduced state [60,185]. Since the sample preparation for the measurements was on air, the natural state for the HS was oxidized.…”

Section: Impact Of Different Extraction Techniquesmentioning

confidence: 99%

“…A difference must also be made between the HS of aquatic and terrestrial origin. Aquatic especially marine HS show a more aliphatic character and the particle sizes are much smaller [60,106]. Due to their size, their many functional groups and their ubiquity, HS belong to the most important organic substances in soils.…”

Section: Introductionmentioning

confidence: 99%

“…They provide nutrition for plants and microbes, not only as source for carbon, but also by mineralizing sulfur, nitrogen and phosphor [54]. HS contribute to the fertility of soils, since they are able to form chelate complexes with single-or multi-valent cations like metal ions [18,60]. They thus play a major role in transport processes, for instance for molecules that would otherwise be immobilized, thereby influencing their bioavailability.…”

Section: Introductionmentioning

confidence: 99%

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Soft x-ray spectromicroscopy of environmental and biological samples

Sedlmair¹

2011

Göttingen Series in X-Ray Physics

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Probing the oxidation–reduction properties of terrestrially and microbially derived dissolved organic matter

Cited by 147 publications

References 41 publications

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

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

Rhodobacter capsulatus Catalyzes Light-Dependent Fe(II) Oxidation under Anaerobic Conditions as a Potential Detoxification Mechanism

Soft x-ray spectromicroscopy of environmental and biological samples

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