Electron paramagnetic resonance (EPR) and stable isotope records of paleoenvironmental conditions during peat formation

Jezierski, Adam; Skrzypek, Grzegorz; Jezierski, Piotr; Paul, Debajyoti; Jędrysek, Mariusz Orion

doi:10.1016/j.saa.2007.09.024

Cited by 13 publications

(10 citation statements)

References 9 publications

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“…Previous studies suggested that the g -factors less than 2.00300 were typical for (C-centered) free radicals 23,24 . Oxygen-centered (O-centered) free radicals usually possess the g -factor larger than 2.00400, such as semiquinone or phenoxyl radicals 25,26 . And radical signals with g -factors of 2.00300–2.00400 are attributed to a combination of the C-centered and O-centered EPFRs 26 .…”

Section: Resultsmentioning

confidence: 99%

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Assessing the effect on the generation of environmentally persistent free radicals in hydrothermal carbonization of sewage sludge

Zhu

Wei

Liu

et al. 2019

Sci Rep

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Environmentally persistent free radicals (EPFRs) have attracted increasing research interest in recent years. Herein, the generation of EPFRs during the hydrothermal carbonization of sewage sludge (SS) was studied. First, the surface morphology, functional groups, constituent elements and free radicals were characterized for a holistic description of the raw SS and the selected hydrochar obtained from hydrothermal carbonization of SS (SHC). Then, the impact of hydrothermal temperature, residence time and initial pH on the formation of EPFRs was explored in detail through the investigation of g-factors and intensities of EPFRs identified in SHC. The results have shown that the formation of EPFRs was affected by the factors mentioned above, in which the impact of temperature is the greatest. Two types of EPFRs were spotted in the hydrochar, oxygen-centered (O-centered) and carbon-centered (C-centered) EPFRs, which were caught in 120–150 °C and 260–280 °C, respectively. Moreover, the intensities of Electron Paramagnetic Resonance (EPR) signals enhanced with increasing hydrothermal temperature. Whereas, residence time and initial pH only affected the amount of EPFRs in a manner. Additionally, the half-life of the O-centered EPFRs and the C-centered EPFRs was determined as long as 160.45 days and 401.10 days, respectively, indicating that EPFRs are stable in a long time.

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Section: Resultsmentioning

confidence: 99%

“…Oxygen-centered (O-centered) free radicals usually possess the g -factor larger than 2.00400, such as semiquinone or phenoxyl radicals 25,26 . And radical signals with g -factors of 2.00300–2.00400 are attributed to a combination of the C-centered and O-centered EPFRs 26 . Obviously, the EPR spectrum of SHC 180-2-7 in Fig.…”

Section: Resultsmentioning

confidence: 99%

Assessing the effect on the generation of environmentally persistent free radicals in hydrothermal carbonization of sewage sludge

Zhu

Wei

Liu

et al. 2019

Sci Rep

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“…In contrast, the non-contaminated/background soil samples exhibited a much weaker signal, a doublet signal for the Georgia soil (g-factors: ~2.00340 and ΔHp-p: ~8.0 Gauss), a singlet signal for the Montana soil (g-factors: ~2.00290 and ΔHp-p: ~6.0 Gauss), and a singlet signal for the Washington sediment (g-factors: ~2.00270 and ΔHp-p: 9.0 Gauss). Such narrow lines with the g-factors between 2.003–2.008 are typical of the organic radicals [5, 26–31]. Based on the intensity of the observed radical signals relative to the mass of the sample, the radical concentration in the contaminated soils and sediments were ~30x, ~12x, and ~2x higher than the non-contaminated counterpart at the Georgia, Montana, and Washington sites, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Radical signals with g-factors of 2.003 and above are attributed to oxygen-centered radicals or carbon-centered radicals with a nearby heteroatom, such as oxygen or halogen that increases the spin-orbit coupling constant [5, 26–31]. Considering the similar source of the soil contamination for the Georgia and Montana sites, the increase in intensity of the radical signal for contaminated soils along with the similarities of the spectral parameters the single paramagnetic signal was attributed to pentachlorophenoxyl as a result of the PCP contamination history.…”

Section: Resultsmentioning

confidence: 99%

“…Such narrow lines with the gfactors between 2.003 and 2.008 are typical of the organic radicals. 5,[26][27][28][29][30][31] Based on the intensity of the observed radical signals relative to the mass of the sample, the radical concentration in the contaminated soils and sediments were $30Â, $12Â, and $2Â higher than the non-contaminated counterpart at the Georgia, Montana, and Washington sites, respectively.…”

Section: Detection Of Epfrsmentioning

confidence: 99%

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Assessment of environmentally persistent free radicals in soils and sediments from three Superfund sites

Cruz

Cook

Dellinger

et al. 2014

Environ. Sci.: Processes Impacts

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We previously reported the presence of environmentally persistent free radicals (EPFRs) in pentachlorophenol (PCP) contaminated soils at a closed wood treatment facility site in Georgia. The reported EPFRs were pentachlorophenoxyl radicals formed on soils under ambient conditions via electron transfer from PCP to electron acceptors in the soil. In this study, we present results for soil and sediment samples from additional Superfund sites in Montana and Washington. Paramagnetic centers associated with different chemical environments were characterized by distinct g-factors and line widths (ΔHp-p). EPFR concentrations in contaminated samples were ~30x, ~12x, and ~2x higher than background samples at the Georgia, Montana, and Washington sites, respectively. EPR signals in the Montana contaminated soils were very similar to those previously observed for pentachlorophenol contaminated soils at the Georgia site, i.e., g = 2.00300 and ΔHp-p = 6.0 G, whereas signals in the Washington sediment samples were similar to those previously observed for other PAH contaminated soils, i.e., g = 2.00270 and ΔHp-p = 9.0G. Total carbon content measurements exhibited direct correlation with EPFR concentration. The presence of radicals in sites contaminated a decade to a century ago suggests continuous formation of EPFRs from molecular contaminants in the soil and sediment.

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Preservation of primary stable isotope signatures of peat-forming plants during early decomposition — observation along an altitudinal transect

2010

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Electron paramagnetic resonance (EPR) and stable isotope records of paleoenvironmental conditions during peat formation

Cited by 13 publications

References 9 publications

Assessing the effect on the generation of environmentally persistent free radicals in hydrothermal carbonization of sewage sludge

Assessing the effect on the generation of environmentally persistent free radicals in hydrothermal carbonization of sewage sludge

Assessment of environmentally persistent free radicals in soils and sediments from three Superfund sites

Preservation of primary stable isotope signatures of peat-forming plants during early decomposition — observation along an altitudinal transect

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