Effects of charging on the chromophores of dissolved organic matter from the Rio Negro basin

Mingquan Yan 1 Gregory V. Korshin 2 Francis Claret 3 Jean-Philippe Croué 4 Massimiliano Fabbricino 5 Hervé Gallard 6 Thorsten Schäfer 7 Marc F. Benedetti 8
1 Peking University [Beijing]
2 Department of Civil Engineering, University of Washington
3 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
4 Université de Poitiers
5 Università degli studi di Napoli Federico II
6 Eaux, Géochimie organique, Santé (E1)
IC2MP - Institut de Chimie des Milieux et Matériaux de Poitiers
7 KIT - Karlsruhe Institute of Technology
8 IPGP - Institut de Physique du Globe de Paris
Abstract : This study demonstrates that the deprotonation of dissolved organic matter (DOM) originating from a small creek characteristic for DOM-rich waters located in the Rio Negro basin can be quantified based on measurements of pH effects on its absorbance spectra. The method was ascertained by the data of Near-Edge X-Ray Absorbance Spectroscopy (NEX-AFS), potentiometric titration to quantify the structural and compositional differences between the colloidal and hydrophobic fractions that contribute 91% of black-water creek DOM. Changes in the absorbance spectra of the DOM fractions caused by deprotonation quantified via numeric deconvolution which indicated the presence of six well-resolved Gaussian bands in the differential spectra. The emergence of these bands was determined to be associated with the engagement of carboxylic and phenolic functionalities and changes of inter-chromophore interactions in DOM molecules. Interpretation of the data based on the NICA-Donnan approach showed that behavior of DOM chromophores was consistent with results of potentiometric titrations. Similar trends were observed for changes of the spectral slope of the DOM absorbance spectra in the range of wavelengths 325-375 nm (DSlope(325-375)). The behavior of DSlope(325-375) values was modeled based on the NICA-Donnan approach and correlated with potentiometrically-estimated charges attributed to the carboxylic and phenolic groups. The correlations between DSlope(325-375) and charges of low- and high-affinity protonation-active groups in DOM were monotonic but not linear and had important differences between the colloidal and hydrophobic fractions.
Keywords : Amazon river Absorbance Deprotonation Dissolved organic matter NEXAFS NICA-Donnan model
Type de document :
Article dans une revue
Water Research, IWA Publishing, 2014, 59, pp.154-164. 〈10.1016/j.watres.2014.03.044〉
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https://hal-brgm.archives-ouvertes.fr/hal-01174189
Contributeur : Anne-Marie Pouget <>
Soumis le : mercredi 8 juillet 2015 - 15:36:43
Dernière modification le : mercredi 19 septembre 2018 - 01:34:36

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BRGM | UNIV-POITIERS | INSU | IC2MP | INC-CNRS | IPGP | USPC

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Mingquan Yan, Gregory V. Korshin, Francis Claret, Jean-Philippe Croué, Massimiliano Fabbricino, et al.. Effects of charging on the chromophores of dissolved organic matter from the Rio Negro basin. Water Research, IWA Publishing, 2014, 59, pp.154-164. 〈10.1016/j.watres.2014.03.044〉. 〈hal-01174189〉

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