Hydrogen peroxide at the Bermuda Atlantic Time Series Station: Temporal variability of seawater hydrogen peroxide

Avery, G. Brooks; Cooper, William J.; Kieber, Robert J.; Willey, Joan D.

doi:10.1016/j.marchem.2005.03.006

Cited by 59 publications

(48 citation statements)

References 30 publications

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“…These photoproduction rates were similar to those measured by Yuan and Shiller (2001) on a 0.4 μm filtered oligotrophic surface sample (5.4 nM h −1 ) from the south central Atlantic, and to those measured by Yocis et al (2000) on 0.2 μm filtered surface samples collected from the oligotrophic Antarctic (2.1 to 9.4 nM h −1 ). Otherwise, most other published open ocean hydrogen peroxide photoproduction rate data are actually net production rates as they were measured either in situ (Avery et al, 2005;Obernosterer et al, 2001) or on unfiltered samples (Yuan and Shiller, 2005) and include biological sinks together with the photochemical source for H 2 O 2 .…”

Section: Resultsmentioning

confidence: 99%

Probing the photochemical reactivity of deep ocean refractory carbon (DORC): Lessons from hydrogen peroxide and superoxide kinetics

et al. 2015

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Most marine DOC is thought to be biologically-recalcitrant, especially that in the deep ocean pool (N 1000 m). In particular, the deep waters of the North Pacific should contain the most recalcitrant DOC because they do not form locally, with deep DOC having survived long isolation from the surface during global-scale thermohaline circulation. One of the proposed removal pathways involves photochemical reactions when refractory DOC circulates through sunlit surface waters (Mopper et al., 1991). Here, we reevaluate the general photoreactivity of refractory DOC by investigating the photochemical production of two reactive oxygen species (ROS), hydrogen peroxide (H 2 O 2 ) and superoxide (O 2 − ), using controlled irradiations at sea and in the laboratory. The photoproduction of these two ROS were compared between deep and surface water samples collected in the Gulf of Alaska. For irradiated samples, initial superoxide steady-state concentrations ([O 2 − ] ss ) and first-order decay constants (k pseudo ) were similar between surface and deep waters, ranging from~1-4 nM and 4-12 × 10 −3 s −1 , respectively. Initial photoproduction rates were comparable between surface and deep waters, ranging from-173 nM h −1 for O 2 − and from 1-8.3 nM h −1 for H 2 O 2 , indicating that a large portion of photoproduced O 2 − does not lead to H 2 O 2 formation. In fact, the photoproduction ratio of O 2 − to H 2 O 2 averaged 4:1 in paired experiments, instead of the 2:1 stoichiometry expected for O 2 − dismutation to form H 2 O 2 . Continued irradiation for up to 48 h showed photoproduced H 2 O 2 to be much lower in deep samples compared to surface samples with accumulation slowing or stopping in deep samples despite both measurable [O 2 −] ss and photon absorbance by colored dissolved organic matter (CDOM). These results are consistent with a loss of source material (i.e. CDOM) for O 2 − photoproduction and a shift to a predominantly oxidative pathway for O 2 − decay. Low photoproduction rates, loss of continued accumulation with extended radiation, and an apparent loss of O 2 − source material argues that the deep refractory DOC pool is less photochemically reactive than previously suggested.

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Section: Resultsmentioning

confidence: 99%

Probing the photochemical reactivity of deep ocean refractory carbon (DORC): Lessons from hydrogen peroxide and superoxide kinetics

et al. 2015

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“…As superoxide is now recognized to be produced in a wide variety of natural contexts (Shaked and Rose, 2013), a steady flux of superoxide may be sufficient to continually reduce Fe(III) complexes to the Fe(II) form, which combined with observed H 2 O 2 concentrations on the order of tens to hundreds of nanomolar (Kieber and Helz, 1995;Avery et al, 2005) may lead to a continual, albeit slow, production pathway for HO • . …”

Section: Marine Implicationsmentioning

confidence: 99%

Importance of Iron Complexation for Fenton-Mediated Hydroxyl Radical Production at Circumneutral pH

2016

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The reaction between Fe(II) and H 2 O 2 to yield hydroxyl radicals (HO • ), the Fenton reaction, is of interest due to its role in trace metal and natural organic matter biogeochemistry, its utility in water treatment and its role in oxidative cell degradation and associated human disease. There is significant dispute over whether HO • , the most reactive of the so-called reactive oxygen species (ROS), is formed in this reaction, particularly under circumneutral conditions relevant to natural systems. In this work we have studied the oxidation kinetics of Fe(II) complexed by L = citrate, ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) and also measured HO • production using phthalhydrazide as a probe compound at pH 8.2. A kinetic model has been developed and utilized to confirm that HO • is the sole product of the Fe(II)L-H 2 O 2 reaction for L = EDTA and DTPA. Quantitative HO • production also appears likely for L = citrate, although uncertainties with the speciation of Fe(II)-citrate complexes as well as difficulties in modeling the oxidation kinetics of these complexes has prevented a definitive conclusion. In the absence of ligands at circumneutral pH, inorganic Fe(II) reacts with H 2 O 2 to yield a species other than HO • , contrary to the well-established production of HO • from inorganic Fe(II) at low pH. Our results suggest that at high pH Fe(II) must be complexed for HO • production to occur.

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“…[2] Hydrogen peroxide (H 2 O 2 ) is a commonly occurring reactive oxygen species (ROS) of great biological and chemical importance. In marine systems H 2 O 2 was shown to play a central role in the cycling of dissolved organic matter, trace metals, pollutants, and a number of highly reactive free radicals [Avery et al, 2005;Moffett and Zika, 1987]. Open ocean H 2 O 2 concentrations are typically below 100 nM and can reach~300 nM in coastal water [Miller et al, 2005;Petasne and Zika, 1997].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of hydrogen peroxide in a coral reef: Sources and sinks

Shaked

Armoza-Zvuloni

2013

JGR Biogeosciences

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[1] The dynamics of hydrogen peroxide (H 2 O 2 ) was studied in the fringing coral reef off the coast of Eilat, Red Sea. Diurnal changes in H 2 O 2 concentrations in the reef lagoon were typical of photochemically produced species. During the daytime H 2 O 2 accumulated in the lagoon at low tide and exceeded open water concentrations by 100-250 nM. Elevated H 2 O 2 decay kinetics (termed hereafter antioxidant activity) were also recorded in the lagoon at low tide. The observed antioxidant activities were high enough to moderate H 2 O 2 accumulation in the lagoon. In pursuit of the antioxidant source, the ability of corals to release antioxidant activity to their surrounding water was examined in both natural and laboratory settings. Water collected in situ from surfaces of individual corals and next to a coral knoll contained high antioxidant activity. Incubation experiments revealed that many Red Sea corals release antioxidant activity to their external milieu. Besides serving a potential antioxidant source to the reef system, the antioxidant activity detected on coral surfaces enabled corals to lower H 2 O 2 concentrations in their vicinity. The ability of corals to offset exogenous H 2 O 2 was validated in incubations with Stylophora pistillata in the absence of mixing. Conversely, corals subjected to mixing in a beaker were found to release H 2 O 2 , implying that corals may act as both a sink and a source for H 2 O 2 in the reef. This newly described ability of corals to change H 2 O 2 dynamics by releasing both H 2 O 2 and antioxidants may bare important implications for coral physiology and interactions with the environment.

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Hydrogen peroxide at the Bermuda Atlantic Time Series Station: Temporal variability of seawater hydrogen peroxide

Cited by 59 publications

References 30 publications

Probing the photochemical reactivity of deep ocean refractory carbon (DORC): Lessons from hydrogen peroxide and superoxide kinetics

Probing the photochemical reactivity of deep ocean refractory carbon (DORC): Lessons from hydrogen peroxide and superoxide kinetics

Importance of Iron Complexation for Fenton-Mediated Hydroxyl Radical Production at Circumneutral pH

Dynamics of hydrogen peroxide in a coral reef: Sources and sinks

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