Photochemically Induced Changes in Dissolved Organic Matter Identified by Ultrahigh Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Gonsior, Michael; Peake, Barrie M.; Cooper, William T.; Podgorski, David C.; D’Andrilli, Juliana

doi:10.1021/es8022804

Cited by 251 publications

(221 citation statements)

References 40 publications

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“…Probably this mechanism can be disregarded for this work. Similar K C results were found by Merdy et al 51 Solar radiation effect on the complexation capacity of AHS Some studies have already shown that solar radiation is able to degrade natural organic matter 19,48 and to interfere in the interaction of these metal species. However, few studies with the same AHS thematic have been addressed in the literature.…”

supporting

confidence: 80%

“…A decrease of fluorescence intensity due to exposure to natural or artificial radiation was observed by other authors by dissolved organic matter. 19,49,52 Gonsior et al 19 verified a fluorescence intensity reduction of 24% for the Preto River water, in California, and verified a greater degradation in compounds that contain fluorescent chromophore groups. They also observed that a concentration of DOC remained constant during radiation.…”

Section: Fluorescence Spectramentioning

confidence: 98%

“…8,16 These authors showed that radiation alters the complexation capacity that the AHS had when not exposed to radiation previously. [16][17][18][19] The role of solar radiation on the complexation capacity is not well understood mainly in tropical regions of the world where solar radiation is intense. Most studies dealing with the capacity complexation of AHS are made with Cu 2+ .…”

Section: Introductionmentioning

confidence: 99%

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Solar radiation effect on the complexation capacity of aquatic humic substances with metals

Melo

Toffoli

Moreira

et al. 2012

J. Braz. Chem. Soc.

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Este estudo teve como principal objetivo avaliar o efeito da radiação solar sobre a capacidade de complexação das substâncias húmicas aquáticas (AHS) com as espécies metálicas Al 3+ , Cr 3+ , CrO 42-e Ni 2+ . Microcosmos foram montados com AHS extraídas do Rio Preto com concentração de 5,0 mg L -1 de carbono orgânico dissolvido e diferentes concentrações de metais, sendo expostos à radiação solar in situ. As constantes de estabilidade condicional foram de 2,0 × 10 -2 , 1,1 × 10 -5 e 2,6 × 10 -2 para os complexos AHS-Cr 3+ , AHS-Ni 2+ e AHS-CrO 4 2-, respectivamente. Os resultados mostraram que a radiação solar foi responsável por um decréscimo na capacidade de complexação de 15-26% para AHS-Al 3+ , 15-72% para AHS-Cr 3+ , 12-18% para AHS-CrO 4 2-e de 13-42% para AHS-Ni 2+ . Conclui-se que a radiação solar altera a disponibilidade de metais previamente complexados às AHS, tornando-os disponíveis no corpo aquático.This study had as main objective to assess the effect of solar radiation on the capacity of the aquatic humic substances (AHS) to complex Al 3+ , Cr 3+ , CrO 4 2-and Ni 2+ . Microcosms were prepared with AHS from Preto River containing 5.0 mg L -1 of dissolved organic carbon and different concentrations of metal species, being exposed to solar radiation, in situ. Conditional stability constants obtained for the AHS-Cr 3+ , AHS-Ni 2+ and AHS-CrO 4 2-complexes were 2.0 × 10 -2 , 1.1 × 10 -5 and 2.6 × 10 -2 , respectively. The results showed that solar radiation is responsible for decreasing capacity complexation in 15-26% for AHS-Al 3+ , 15-72% for AHS-Cr 3+ , 12-18% for AHS-CrO 4 2-and 13-42% for AHS-Ni 2+ . We can conclude that solar radiation alters metals' availability previously complexed to AHS, making them available in the aquatic body.Keywords: aquatic humic substances, metal complexation, solar radiation, fluorescence IntroductionAquatic humic substances (AHS) have been intensively studied because they play an essential role in biogeochemical processes. 1,2 They can participate in the complexation reactions with metal ions thereby influencing the transport and availability of them in the environment, 2-4 may suffer interactions with organic compounds and thus, reduce or increase its toxicity to the biota, 4,5 can act in redox 6 and photochemical reactions. 7 Aquatic HS are products of the decomposition of vegetal and animal remains from microbiological transformations. They are normally dark colored organic macromolecules with a high molecular weight, a complex structure consisting of aromatic and aliphatic compounds, which have a large number of functional groups containing oxygen, e.g., carboxylates (-COOH), phenolics (aromatics-OH), alcoholics (-OH), quinones (aromatics=O), among others. 1,2 Depending on the water solubility, AHS can be operationally separated into three fractions: fulvic acids that are soluble in all pH range, humic acids that are soluble in alkaline pH and insoluble in acid pH, and humin that is insoluble in all pH range. It is worth noting that the AHS comprise about 40-60% ...

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supporting

confidence: 80%

Section: Fluorescence Spectramentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Solar radiation effect on the complexation capacity of aquatic humic substances with metals

Melo

Toffoli

Moreira

et al. 2012

J. Braz. Chem. Soc.

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“…under the assumption that most DOM oxygen is bound to carbon by a double bond (40,41). In contrast with DBE, the DBE−O distribution is lower in bog than in fen DOM (Fig.…”

Section: Resultsmentioning

confidence: 95%

Changes in peat chemistry associated with permafrost thaw increase greenhouse gas production

Hodgkins¹,

Tfaily²,

McCalley

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

288

362

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Carbon release due to permafrost thaw represents a potentially major positive climate change feedback. The magnitude of carbon loss and the proportion lost as methane (CH 4 ) vs. carbon dioxide (CO 2 ) depend on factors including temperature, mobilization of previously frozen carbon, hydrology, and changes in organic matter chemistry associated with environmental responses to thaw. While the first three of these effects are relatively well understood, the effect of organic matter chemistry remains largely unstudied. To address this gap, we examined the biogeochemistry of peat and dissolved organic matter (DOM) along a ∼40-y permafrost thaw progression from recently-to fully thawed sites in Stordalen Mire (68.35°N,19.05°E), a thawing peat plateau in northern Sweden. Thaw-induced subsidence and the resulting inundation along this progression led to succession in vegetation types accompanied by an evolution in organic matter chemistry. Peat C/N ratios decreased whereas humification rates increased, and DOM shifted toward lower molecular weight compounds with lower aromaticity, lower organic oxygen content, and more abundant microbially produced compounds. Corresponding changes in decomposition along this gradient included increasing CH 4 and CO 2 production potentials, higher relative CH 4 /CO 2 ratios, and a shift in CH 4 production pathway from CO 2 reduction to acetate cleavage. These results imply that subsidence and thermokarst-associated increases in organic matter lability cause shifts in biogeochemical processes toward faster decomposition with an increasing proportion of carbon released as CH 4 . This impact of permafrost thaw on organic matter chemistry could intensify the predicted climate feedbacks of increasing temperatures, permafrost carbon mobilization, and hydrologic changes.H igh-latitude soils in the Northern Hemisphere contain an estimated 1,400-1,850 petagrams (Pg) of carbon, of which ∼277 Pg is in peatlands within the permafrost zone (1, 2). This quantity of 277 Pg represents over one-third of the carbon stock in the atmosphere (ca. 800 Pg) (3). The fate of this carbon in a warming climate-i.e., the responses of net carbon balance and CH 4 emissions-is important in predicting climate feedbacks of permafrost thaw. Although northern peatlands are currently a net carbon sink, and have been since the end of the last glaciation, they are a net source of CH 4 (4, 5), emitting 0.046-0.09 Pg of carbon as CH 4 per year (4, 6, 7). Due to CH 4 's disproportionate global warming potential (33× CO 2 for 1 kg CH 4 vs. 1 kg CO 2 at a 100-y timescale) (8), this is equivalent to 6-12% of annual fossil fuel emissions of CO 2 (8.7 Pg of C) (9). The thaw of permafrost peatlands may alter their CH 4 and CO 2 emissions due to mobilization of formerly frozen carbon, higher temperatures, altered redox conditions, and evolving organic matter chemistry. Changes in carbon emissions, and in CH 4 emission in particular, could have potentially significant climate impacts. CH 4 is produced by two primary mechanisms (10-12),...

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“…The burgeoning use of mass spectrometry in DOM studies has tremendously advanced our molecular-level understanding of DOM dynamics [11][12][13][14][15] . Recent developments in data processing now enable us to analyze the detailed molecular composition of DOM as a function of environmental gradients over a large number of samples.…”

mentioning

confidence: 99%

Chemodiversity of dissolved organic matter in lakes driven by climate and hydrology

et al. 2014

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Despite the small continental coverage of lakes, they are hotspots of carbon cycling, largely due to the processing of terrestrially derived dissolved organic matter (DOM). As DOM is an amalgam of heterogeneous compounds comprising gradients of microbial and physicochemical reactivity, the factors influencing DOM processing at the molecular level and the resulting patterns in DOM composition are not well understood. Here we show, using ultrahigh-resolution mass spectrometry to unambiguously identify 4,032 molecular formulae in 120 lakes across Sweden, that the molecular composition of DOM is shaped by precipitation, water residence time and temperature. Terrestrially derived DOM is selectively lost as residence time increases, with warmer temperatures enhancing the production of nitrogen-containing compounds. Using biodiversity concepts, we show that the molecular diversity of DOM, or chemodiversity, increases with DOM and nutrient concentrations. The observed molecular-level patterns indicate that terrestrially derived DOM will become more prevalent in lakes as climate gets wetter.

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Photochemically Induced Changes in Dissolved Organic Matter Identified by Ultrahigh Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Cited by 251 publications

References 40 publications

Solar radiation effect on the complexation capacity of aquatic humic substances with metals

Solar radiation effect on the complexation capacity of aquatic humic substances with metals

Changes in peat chemistry associated with permafrost thaw increase greenhouse gas production

Chemodiversity of dissolved organic matter in lakes driven by climate and hydrology

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