Ocean Acidification Effect on the Iron-Gallic Acid Redox Interaction in Seawater

Pérez-Almeida, Norma; González, Aridane G.; Santana‐Casiano, J. Magdalena; González‐Dávila, Melchor

doi:10.3389/fmars.2022.837363

Cited by 13 publications

(8 citation statements)

References 120 publications

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“…In order to reveal whether trace •OH was produced that cannot be detected by ESR, coumarin was used as the probe to detect •OH, but the hydroxylated product (7-hydroxy coumarin) was not detected (Figure S6), indicating that negligible •OH was produced during the Fe-PC reactions even in well-oxygenated conditions. In general, ROS can be generated through the oxygenation of Fe(II), but the oxygenation of Fe(II) in the acidic condition is negligible; , in addition, the formation of Fe-PC complexes can protect Fe(II) from oxidation. − This is likely the main reason why ROS was not detected in this study.…”

Section: Resultsmentioning

confidence: 78%

Molecular-Scale Investigation on the Formation of Brown Carbon Aerosol via Iron-Phenolic Compound Reactions in the Dark

Tang

et al. 2023

Environ. Sci. Technol.

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Brown carbon (BrC) is one of the most mysterious aerosol components responsible for global warming and air pollution. Iron (Fe)-induced catalytic oxidation of ubiquitous phenolic compounds has been considered as a potential pathway for BrC formation in the dark. However, the reaction mechanism and product composition are still poorly understood. Herein, 13 phenolic precursors were employed to react with Fe under environmentally relevant conditions. Using Fourier transform ion cyclotron resonance mass spectrometry, a total of 764 unique molecular formulas were identified, and over 85% of them can be found in atmospheric aerosols. In particular, products derived from precursors with catechol-, guaiacol-, and syringol-like-based structures can be distinguished by their optical and molecular characteristics, indicating the structure-dependent formation of BrC from phenolic precursors. Multiple pieces of evidence indicate that under acidic conditions, the contribution of either autoxidation or oxygen-induced free radical oxidation to BrC formation is extremely limited. Ligand-to-Fe charge transfer and subsequent phenoxy radical coupling reactions were the main mechanism for the formation of polymerization products with high molecular diversity, and the efficiency of BrC generation was linearly correlated with the ionization potential of phenolic precursors. The present study uncovered how chemically diverse BrC products were formed by the Fe-phenolic compound reactions at the molecular level and also provide a new paradigm for the study of the atmospheric aerosol formation mechanism.

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Section: Resultsmentioning

confidence: 78%

Molecular-Scale Investigation on the Formation of Brown Carbon Aerosol via Iron-Phenolic Compound Reactions in the Dark

Tang

et al. 2023

Environ. Sci. Technol.

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“…The presence of strong Cu-binding ligands in surface seawaters stabilizes the excess of dissolved copper 21 . Carbohydrates and phenolic compounds can influence metal ion chemistry and bioavailability 2 , 22 . Catechin, sinapic acid and gallic acid were found to increase the persistence of dissolved Fe, regenerating Fe(II) in seawater from 0.05 to 11.92% 23 .…”

Section: Introductionmentioning

confidence: 99%

Characterization of polyphenols and carbohydrates exuded by Phaeodactylum tricornutum diatom grown under Cu stress

Rico,

Santiago-Díaz,

Rivero

et al. 2024

Sci Rep

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This study is focused on analysing polyphenols and carbohydrates released by Phaeodactylum tricornutum (P. tricornutum) diatoms cultured in natural seawater enriched with sublethal and lethal Cu doses. Cu concentrations of 0.31, 0.79 and 1.57 µM reduced cell densities by 37, 82 and 91%, respectively, compared to the control. The total sum of all identified polyphenols and total carbohydrates released by cells grown under lethal Cu levels increased up to 18.8 and 107.4 times, respectively, compared to data from a control experiment. Four different in vitro assays were used to estimate the antioxidant activities of the extracellular compounds: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition, cupric ion reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power and Cu complexing ability (CCA). The highest antioxidant activities were observed in the Cu lethal treatments, where the CCA assay exhibited a greater increase (up to 32.2 times higher than that found in the control experiment) to reduce the concentration of free Cu in the medium and its toxicity. The presence of Cu stimulated the release of polyphenols and carbohydrates to the medium as a detoxification mechanism to survive under lethal levels of Cu regulating its speciation.

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“…Organic matter exuded by marine microorganisms can form Fe(III) complexes that modify Fe(II) oxidation rates and promote the reduction of Fe(III) to Fe(II) in seawater. Under acidifying conditions, some research work has shown that the residence time of the reduced form of essential trace metals increases as their oxidation rate decreases (Pérez-Almeida et al, 2022;Santana-Casiano et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Variations of polyphenols and carbohydrates of Emiliania huxleyi grown under simulated ocean acidification conditions

Rico,

Santiago-Díaz,

Samperio-Ramos

et al. 2024

Preprint

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Abstract. Global environmental changes strongly affect the growth and biochemical composition of microalgae. Cultures of the coccolithophore Emiliania huxleyi were grown under four different CO2-controlled pH conditions (7.75, 7.90, 8.10, and 8.25) to improve understanding of the adaptive mechanisms of these organisms through changes in phenolic compounds and carbohydrate content and composition under ocean acidification (OA) scenarios. The highest algal biomass peaks, 1.07 (± 0.10) and 1.04 (± 0.06) × 108 cells L−1, were observed in the microcosms with intermediate CO2 levels (pH 8.10 and 7.90 respectively). Intra- and extracellular phenolic compounds were identified and quantified by Reverse Phase-High Performance Liquid Chromatography (RP-HPLC). The highest concentrations of total exuded phenolics were found in cultures with lower cell densities, at pH 8.25 (43±3 nM) and 7.75 (18.0±0.9 nM). Accumulation of intracellular phenolic compounds was observed in cells with decreasing pH, reaching the maximum level (9.24±0.19 attomole cell-1) at the lowest pH (7.75). The total carbohydrate content inside the cells increased with decreasing pH from 8.25 to 8.10, remaining constant at pH 7.90, and decreasing at lower pH. The presence of antioxidants was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition and ferric-reducing antioxidant power (FRAP) assays. The highest activity in both tests was exhibited by cells grown at pH 7.75.

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Ocean Acidification Effect on the Iron-Gallic Acid Redox Interaction in Seawater

Cited by 13 publications

References 120 publications

Molecular-Scale Investigation on the Formation of Brown Carbon Aerosol via Iron-Phenolic Compound Reactions in the Dark

Molecular-Scale Investigation on the Formation of Brown Carbon Aerosol via Iron-Phenolic Compound Reactions in the Dark

Characterization of polyphenols and carbohydrates exuded by Phaeodactylum tricornutum diatom grown under Cu stress

Variations of polyphenols and carbohydrates of Emiliania huxleyi grown under simulated ocean acidification conditions

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