A Model to Predict the Steady‐State Concentration of Hydroxyl Radicals in the Surface Layer of Natural Waters

Minero, Claudio; Lauri, Vittorio; Maurino, Valter; Pelizzetti, Ezio; Vione, Davide

doi:10.1002/adic.200790053

Cited by 14 publications

(6 citation statements)

References 33 publications

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“…On the basis of DOC from 10 to 100 mg/L, CH 4 from 0.1 to 1.5 mM, and HS – from 0.05 to 2 mM (assuming [H 2 S] T = [HS – ]), [·OH] ss could plausibly range from 5.7 × 10 –19 to 3.2 × 10 –18 M in porewaters (Figure ), assuming a steady dissolved oxygen concentration of 52 μM. This concentration range could have an effect on the chemistry and degradation rates in the environment and corresponds to the lower range of [·OH] ss in sunlit surface waters. , Even though the modeled sulfidic system has a lower [·OH] ss , ·OH in sulfidic waters could lead to consistent degradation that does not depend on solar conditions. The steady state concentration is most dependent on [H 2 S] T , as expected.…”

Section: Resultsmentioning

confidence: 99%

Determination of Hydroxyl Radical Production from Sulfide Oxidation Relevant to Sulfidic Porewaters

Lombardo

Vindedahl

Arnold

2020

ACS Earth Space Chem.

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Hydroxyl radical (·OH) production from the reaction between aqueous total sulfide ([H2S]T = [H2S] + [HS–] + [S2–]) and dissolved oxygen is potentially an environmentally important reaction when anoxic, sulfidic water is exposed to oxygen. Using hydroxyterephthalate (hTPA) formation from the reaction of terephthalic acid (TPA) with ·OH as a probe for ·OH production, hydrogen peroxide was verified as an essential intermediate, and the production of free ·OH, versus lower energy hydroxylating agents, was established. The optimal conditions for the quantification of ·OH production kinetics and yield were determined by varying TPA and total sulfide concentrations. An initial total sulfide concentration of 10 μM and TPA concentration of 2 mM was used to find a yield of 15 mmol of ·OH per mole [H2S]T. Additionally, a pseudo-first-order model elucidated a maximum rate of production of 1.04 (±0.05) × 10–4 moles of ·OH per hour per mole of [H2S]T. Experiments with sulfidic wetland porewaters containing up to 294 mg/L of dissolved organic carbon (DOC) revealed that [H2S]T, and not reduced DOC, was the dominant source of ·OH. A simple model considering a water containing [H2S]T, DOC, and methane exposed to a constant concentration of oxygen (∼50 μM) gave steady state values of [·OH] ranging from 5.7 × 10–19 to 3.2 × 10–18 M. The results indicate that [H2S]T should be considered a source of dark formation of ·OH in addition to ferrous iron and reduced DOC.

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Section: Resultsmentioning

confidence: 99%

Determination of Hydroxyl Radical Production from Sulfide Oxidation Relevant to Sulfidic Porewaters

Lombardo

Vindedahl

Arnold

2020

ACS Earth Space Chem.

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“…[25,147] Exceptions may be represented by the (presumably rare) cases in which inorganic carbon is an important COH scavenger and nitrate and/or nitrite are very minor sources. [148] The evolution of this scenario is modeled in Figure 2, in which the steady-state [COH] is plotted as a function of nitrite and DOC.…”

Section: Hydroxyl Radicals (Coh)mentioning

confidence: 99%

Indirect Photochemistry in Sunlit Surface Waters: Photoinduced Production of Reactive Transient Species

Vione

Minella

Maurino

et al. 2014

Chemistry A European J

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376

294

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This paper gives an overview of the main reactive transient species that are produced in surface waters by sunlight illumination of photoactive molecules (photosensitizers), such as nitrate, nitrite, and chromophoric dissolved organic matter (CDOM). The main transients (˙OH, CO3(-˙) , (1)O2, and CDOM triplet states) are involved in the indirect phototransformation of a very wide range of persistent organic pollutants in surface waters.

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“…Sampling locations and dates are reported elsewhere 9,11,12 or can be provided on request. The samples were collected from the water surface layer with Pyrex glass bottles, and kept refrigerated during transport to the laboratory.…”

Section: Methodsmentioning

confidence: 99%

“…[1][2][3][4] Additionally they play an important role, together with nitrite, in water photochemistry and photobiology concerning both the transformation of dissolved molecules [5][6][7][8][9][10][11][12] plus the connected possible production of harmful compounds, 13,14 and the penetration of radiation inside the water column. [15][16][17] DOM also plays a crucial role in defining the water solubility and bioavailability of toxic metal species and complexes, and of organic pollutants.…”

Section: Introductionmentioning

confidence: 99%

Spectrophotometric Characterisation of Surface Lakewater Samples: Implications for the Quantification of Nitrate and the Properties of Dissolved Organic Matter

et al. 2007

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Filtered lakewater samples, mainly collected in the province of Torino (Piedmont, NW Italy) were characterised from a spectrophotometric point of view. Spectral data were then used for the direct determination of nitrate by three-wavelength photometry, which should account for the spectral interference by dissolved organic matter (DOM), and the results compared with nitrate quantification by ion chromatography. The spectrophotometric method proved very suitable for nitrate measurement, with unity slope (micro +/- sigma = 0.99 +/- 0.03) of the correlation plot (spectral vs. ion chromatography data) up to 0.1 mM nitrate, and with r2 = 0.97 for 26 data points. Lakewater spectra were also used for the characterisation of DOM by means of the specific absorption at 285 and 254 nm (absorbance vs. NPOC, the latter to quantify the DOM amount), and the E2/E3 and E3/E4 indexes. The latter two make only use of radiation absorption data (250 vs. 365 and 300 vs. 400 nm). It could be concluded that lakewater DOM is mainly composed of autochthonous material (biologically produced aliphatic compounds and only a minor fraction of aromatic groups), with generally low molecular weight and degree of aromaticity. Some exceptions could be found in high-mountain lakes, but it should also be considered that NPOC measurement cannot be avoided if DOM origin is to be studied. From the absorption spectrum alone it is possible to get indication on the aromaticity degree of radiation-absorbing DOM, but most of the autochthonous DOM would escape spectrophotometric characterisation.

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A Model to Predict the Steady‐State Concentration of Hydroxyl Radicals in the Surface Layer of Natural Waters

Cited by 14 publications

References 33 publications

Determination of Hydroxyl Radical Production from Sulfide Oxidation Relevant to Sulfidic Porewaters

Determination of Hydroxyl Radical Production from Sulfide Oxidation Relevant to Sulfidic Porewaters

Indirect Photochemistry in Sunlit Surface Waters: Photoinduced Production of Reactive Transient Species

Spectrophotometric Characterisation of Surface Lakewater Samples: Implications for the Quantification of Nitrate and the Properties of Dissolved Organic Matter

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