Comparison of the properties of standard soil and aquatic fulvic and humic acids based on the data of differential absorbance and fluorescence spectroscopy

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This study compared effects of pH, ionic strength and complexation with Mg2+ on the chromophores and fluorophores of aquatic and terrestrial NOM exemplified by the standard isolates Suwannee River fulvic and humic acid (SRFA and SRHA) and Pahokee Peat fulvic and humic acids (PPFA and PPHA) provided by the International Humic Substance Society (IHSS). The intensity of the differential spectra of the NOM isolates increased monotonically with pH. These spectra comprised contributions of similar chromophore systems associated with the carboxylic and phenolic moieties. The intensity of SRFA and PPFA fluorescence changed non-monotonically vs. pH indicating that the deprotonation of the phenolic fluorophores decreased their emission yields. Examination of the effects of pH on the slopes of the log-transformed absorbance of NOM showed that the influence of deprotonation on the conformations of PPFA and PPHA molecules was less prominent than those for SRFA but not dissimilar to those of SRHA. Changes of the differential spectra and spectral slopes showed that Mg2+/PPFA and Mg2+/PPHA complexation was more effected by electrostatic interactions while the involvement of phenolic groups was notable for SRFA. The observed trends highlight similarities and differences in the properties of the chromophores and fluorophores in the standard isolates of soil and aquatic NOM. These results necessitate further systematic comparison of the properties of NOM isolates and those of unaltered NOM.

Medienart:

E-Artikel

Erscheinungsjahr:

2020

Erschienen:

2020

Enthalten in:

Zur Gesamtaufnahme - volume:261

Enthalten in:

Chemosphere - 261(2020) vom: 28. Dez., Seite 128189

Sprache:

Englisch

Beteiligte Personen:

Liu, Siqi [VerfasserIn]
Benedetti, Marc F [VerfasserIn]
Han, Weiqing [VerfasserIn]
Korshin, Gregory V [VerfasserIn]

Links:

Volltext

Themen:

Aquatic NOM
Benzopyrans
Comparative Study
Differential absorbance spectroscopy
Fluorescence
Fulvic acid
Humic Substances
I38ZP9992A
Journal Article
Magnesium
Potentiometry
Protonation
Soil
Soil NOM
XII14C5FXV

Anmerkungen:

Date Completed 13.11.2020

Date Revised 13.11.2020

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.chemosphere.2020.128189

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM316822590