Environmental pH and ionic strength influence the electron-transfer capacity of dissolved organic matter

Lu, Qin; Yuan, Yong; Tao, Ya; Tang, Jia

doi:10.1007/s11368-015-1154-y

Cited by 23 publications

(18 citation statements)

References 42 publications

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“…Therefore, reduced soil acidity leads to a decrease in the adsorption capacity of the soil, increased DOM solubility, and higher export of terrestrial DOM (Jardine, McCarthy, & Weber, 1989). The mobilized DOM has high molecular weight and a high sensitivity to ultraviolet (UV) light and photoreactive damage (Lu, Yuan, Tao, & Tang, 2015;SanClements et al, 2012;Timko, Gonsior, & Cooper, 2015). Due to these properties, the mobilized DOM may be less available to bacterial uptake ( Figure 2) (Ekstr€ om et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Global change‐driven effects on dissolved organic matter composition: Implications for food webs of northern lakes

Creed

Bergström

Trick

et al. 2018

Global Change Biology

261

213

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Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial-aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)-the messenger between terrestrial and lake ecosystems-with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.

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Section: Introductionmentioning

confidence: 99%

Global change‐driven effects on dissolved organic matter composition: Implications for food webs of northern lakes

Creed

Bergström

Trick

et al. 2018

Global Change Biology

261

213

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“…For example, the presence of 5 mM Mg 2+ only slightly (6–14%) decreased the rates of ·OH production, and the ·OH production rates in the presence of 20 mM Mg 2+ was similar to or slightly higher than the rates observed in the presence of 5 mM Ca 2+ (Figure , Table S2). The decrease in the production of ·OH caused by Ca 2+ /Mg 2+ was likely due to multiple factors such as (1) blocking of the active site of reduced HA due to complexation and aggregation and (2) suppression of the redox reactivity of reduced HA. ,,,, …”

Section: Resultsmentioning

confidence: 99%

“…In addition, both Ca 2+ and Mg 2+ can increase the ionic strength of solution that neutralizes the negative surface charges of HAs, which could lower the inter- and intramolecular electrostatic repulsions, leading to the molecular shrinking of HAs . This molecule compression has been found to decrease the electron-transfer capacity of HA .…”

Section: Resultsmentioning

confidence: 99%

“…Both Ca 2+ and Mg 2+ ions are abundant in natural waters and may have a significant impact on the properties of HA and HA-Fe(II) complexes. ,, Ca 2+ and Mg 2+ can increase the solution ionic strength and decrease the negative charges of HA, both of which may result in aggregation of HA. − This may subsequently influence the redox reactivity of HA . In natural waters, the concentrations of Ca 2+ and Mg 2+ were found to be typically higher than that of Fe 2+ .…”

Section: Introductionmentioning

confidence: 99%

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Impact of Divalent Cations on Dark Production of Hydroxyl Radicals from Oxygenation of Reduced Humic Acids at Anoxic–Oxic Interfaces

Liao

Yao

Shi

2019

ACS Earth Space Chem.

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Humic acids (HAs) are redox-active and can serve as either electron acceptors or electron donors to participate in multiple redox reactions. In nature water, HA can be intimately associated with divalent cations, such as Fe 2+ , Ca 2+ , and Mg 2+ , through a series of reactions that may in turn affect the redox reactivity of HA. Recent advances have demonstrated that the oxygenation of reduced HA in the dark can produce •OH at anoxic−oxic interfaces. However, little is known about the roles of the divalent cations complexed with HA on the production of •OH from reduced HA. This study provides new knowledge regarding the impact of Fe 2+ , Ca 2+ , and Mg 2+ ions on the dark production of •OH from oxygenation of reduced HA at anoxic−oxic interfaces over a wide range of environmentally relevant conditions. Results show that the rates and yields of •OH production increase with increasing Fe 2+ concentration (0.18−0.89 mM). This is largely attributed to the formation of complexed Fe(II) with HA, which increases the number of Fe(II)/Fe(III) cycles and enhances the decomposition of formed H 2 O 2 , accelerating the rates of Fenton reactions under circumneutral conditions. However, the promotional effect of Fe 2+ on •OH formation is greatly suppressed in the coexistence of high Ca 2+ /Mg 2+ concentration (5−20 mM), likely due to the retarded formation of HA-Fe(II) complexes and competition of HA surface reactive sites by Ca 2+ /Mg 2+ ions. Findings improve the current understanding of the dark production of •OH from reduced HA and provide valuable insights toward understanding of carbon cycling and contaminant fate at anoxic−oxic interfaces.

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“…2The electron transfer capacity of HS depends on the pH, and single electron transfer process between the quinone, semiquinone and hydroquinone in HS is affected by the pH [33,34]. The electron transfer capacity of HS increases with the growth of pH [35]. (3) Oxygen has protective effect on some redox sites of HS which result in the electron transfer capacity of HS is weakened, only few functional groups could transfer electrons [36].…”

Section: Environmental Factorsmentioning

confidence: 99%

Humic substances and its electron transfer capacity during composting: A review

Dai

et al. 2020

E3S Web Conf.

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Humic substances (HS) are important product during composting, which play a key role in the maturity of compost, and its electron transfer characteristics have significant applications in the reduction of pollutants. We focus on the structure and composition characteristics and formation mechanism of HS during the composting. The effects of composting raw materials, additives, microorganisms and oxygen supply conditions on the formation of HS were reviewed. The electron transfer mechanism of compost HS was summarized as well as the structural and environmental factors affect the electron transfer of HS. The applications of HS in soil pollution control and water treatment are introduced. The research directions of HS formation mechanism, electron transfer mechanism and its application are also prospected.

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Environmental pH and ionic strength influence the electron-transfer capacity of dissolved organic matter

Cited by 23 publications

References 42 publications

Global change‐driven effects on dissolved organic matter composition: Implications for food webs of northern lakes

Global change‐driven effects on dissolved organic matter composition: Implications for food webs of northern lakes

Impact of Divalent Cations on Dark Production of Hydroxyl Radicals from Oxygenation of Reduced Humic Acids at Anoxic–Oxic Interfaces

Humic substances and its electron transfer capacity during composting: A review

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