Electrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat

Exposure to oxygen and aerobic biological activity during drought periods alters the availability of terminal electron acceptors (TEA) in the peat catotelm layer. We investigated the changes in the electrochemical and chemical characteristics of humic acids (HA) induced by subjecting air-dried sphag...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Carlo Bravo, Rosanna Toniolo, Marco Contin, Maria De Nobili
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	humic acids peat redox changes electron donating capacity electron transfer kinetic constants Agriculture S
Acceso en línea:	https://doaj.org/article/f578664533e34c4cbc31b4e274e1e71f
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:f578664533e34c4cbc31b4e274e1e71f
record_format	dspace
spelling	oai:doaj.org-article:f578664533e34c4cbc31b4e274e1e71f2021-11-25T18:09:33ZElectrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat10.3390/land101111892073-445Xhttps://doaj.org/article/f578664533e34c4cbc31b4e274e1e71f2021-11-01T00:00:00Zhttps://www.mdpi.com/2073-445X/10/11/1189https://doaj.org/toc/2073-445XExposure to oxygen and aerobic biological activity during drought periods alters the availability of terminal electron acceptors (TEA) in the peat catotelm layer. We investigated the changes in the electrochemical and chemical characteristics of humic acids (HA) induced by subjecting air-dried sphagnum peat to biological oxidation or reduction during a 90-day incubation experiment. Structural modifications of HAs from anaerobically (HA<sub>red</sub>) and aerobically (HA<sub>ox</sub>) incubated peat were investigated by ATR-FTIR, UV–vis, and EEM fluorescence spectroscopy. Number and strength of acid groups were characterized by titration, while changes in redox properties were characterized by cyclic voltammetry and quantified by coulometry with mediated electrochemical oxidation (MEO). Exposure to oxygen had small effects, but compared to anaerobic incubation, decreased by 20% the capacity of HA to reduce the radical ion of 2,2′-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS<sup>●−</sup>), passing from 2.77 ± 0.13 mmol<sub>e-</sub> g<sub>HA</sub><sup>−1</sup> in HA<sub>red</sub> to 2.21 ± 0.10 mmol<sub>e-</sub> g<sub>HA</sub><sup>−1</sup> in HA<sub>ox</sub>. Pseudo-first-order electron transfer kinetic constants were 13.3 ± 1.2 s<sup>−1</sup> for HA<sub>ox</sub> and 16.7 ± 1.4 s<sup>−1</sup> for HA<sub>red</sub>. Alterations in the hydrological status of the catotelm have minor effects on the actual in situ availability of organic TEA, but if coupled to intensified biological activity they may result in significant variations of greenhouse gases emissions.Carlo BravoRosanna TonioloMarco ContinMaria De NobiliMDPI AGarticlehumic acidspeatredox changeselectron donating capacityelectron transfer kinetic constantsAgricultureSENLand, Vol 10, Iss 1189, p 1189 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	humic acids peat redox changes electron donating capacity electron transfer kinetic constants Agriculture S
spellingShingle	humic acids peat redox changes electron donating capacity electron transfer kinetic constants Agriculture S Carlo Bravo Rosanna Toniolo Marco Contin Maria De Nobili Electrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat
description	Exposure to oxygen and aerobic biological activity during drought periods alters the availability of terminal electron acceptors (TEA) in the peat catotelm layer. We investigated the changes in the electrochemical and chemical characteristics of humic acids (HA) induced by subjecting air-dried sphagnum peat to biological oxidation or reduction during a 90-day incubation experiment. Structural modifications of HAs from anaerobically (HA<sub>red</sub>) and aerobically (HA<sub>ox</sub>) incubated peat were investigated by ATR-FTIR, UV–vis, and EEM fluorescence spectroscopy. Number and strength of acid groups were characterized by titration, while changes in redox properties were characterized by cyclic voltammetry and quantified by coulometry with mediated electrochemical oxidation (MEO). Exposure to oxygen had small effects, but compared to anaerobic incubation, decreased by 20% the capacity of HA to reduce the radical ion of 2,2′-Azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS<sup>●−</sup>), passing from 2.77 ± 0.13 mmol<sub>e-</sub> g<sub>HA</sub><sup>−1</sup> in HA<sub>red</sub> to 2.21 ± 0.10 mmol<sub>e-</sub> g<sub>HA</sub><sup>−1</sup> in HA<sub>ox</sub>. Pseudo-first-order electron transfer kinetic constants were 13.3 ± 1.2 s<sup>−1</sup> for HA<sub>ox</sub> and 16.7 ± 1.4 s<sup>−1</sup> for HA<sub>red</sub>. Alterations in the hydrological status of the catotelm have minor effects on the actual in situ availability of organic TEA, but if coupled to intensified biological activity they may result in significant variations of greenhouse gases emissions.
format	article
author	Carlo Bravo Rosanna Toniolo Marco Contin Maria De Nobili
author_facet	Carlo Bravo Rosanna Toniolo Marco Contin Maria De Nobili
author_sort	Carlo Bravo
title	Electrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat
title_short	Electrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat
title_full	Electrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat
title_fullStr	Electrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat
title_full_unstemmed	Electrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat
title_sort	electrochemical and structural modifications of humic acids in aerobically and anaerobically incubated peat
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/f578664533e34c4cbc31b4e274e1e71f
work_keys_str_mv	AT carlobravo electrochemicalandstructuralmodificationsofhumicacidsinaerobicallyandanaerobicallyincubatedpeat AT rosannatoniolo electrochemicalandstructuralmodificationsofhumicacidsinaerobicallyandanaerobicallyincubatedpeat AT marcocontin electrochemicalandstructuralmodificationsofhumicacidsinaerobicallyandanaerobicallyincubatedpeat AT mariadenobili electrochemicalandstructuralmodificationsofhumicacidsinaerobicallyandanaerobicallyincubatedpeat
_version_	1718411596137496576

Electrochemical and Structural Modifications of Humic Acids in Aerobically and Anaerobically Incubated Peat

Ejemplares similares