Heterogeneity as a concept in the interpretation of metal ion binding by humic substances. The binding of zinc by an aquatic fulvic acid

Humic substances are soil and fresh-water components that play an important role in the binding and transport of both organic and inorganic contaminants. Transport of the contaminants due to ground- and fresh-water dynamics is directly related to the risks associated with contaminations. The mobility of soluble humic substances is related to their interaction with soil mineral particles. Some key references for the binding of organic and inorganic contaminants and for the binding of humics to mineral particles are presented. Humic substances also play a role in the analysis of the contaminants in natural waters and with remediation of water or soil polluted with pesticides, heavy metal ions, and radionuclides. These aspects are illustrated with some examples. The problems that are encountered with the modeling of the binding of contaminants to humics and of heavy metal ions in particular are illustrated by considering the nonideal competitive adsorption model (NICA) extended with electrostatic interactions. The NICA-Donnan model gives quite good results for the description of metal ion binding, as is illustrated for metal ion binding to purified peat humic acid (PPHA). Finally, some remarks are made with respect to the use of the NICA-Donnan model in general purpose speciation programs and of simplified versions of the model for predictions under restricted environmental conditions.

Download Full-text

Computational scheme for the prediction of metal ion binding by a soil fulvic acid

Analytica Chimica Acta ◽

10.1016/0003-2670(94)00491-4 ◽

1995 ◽

Vol 302 (2-3) ◽

pp. 309-322 ◽

Cited By ~ 8

Author(s):

J.A. Marinsky ◽

M.M. Reddy ◽

J.H. Ephraim ◽

A.S. Mathuthu

Keyword(s):

Fulvic Acid ◽

Metal Ion ◽

Computational Scheme ◽

Ion Binding ◽

Metal Ion Binding

Download Full-text

Data Treatments for Relating Metal-Ion Binding to Fulvic Acid as Measured by Fluorescence Spectroscopy

ACS Symposium Series - Humic and Fulvic Acids ◽

10.1021/bk-1996-0651.ch008 ◽

1996 ◽

pp. 108-124 ◽

Cited By ~ 1

Author(s):

Michael D. Hays ◽

David K. Ryan ◽

Stephen Pennell ◽

Lisa Ventry Milenkovic

Keyword(s):

Fluorescence Spectroscopy ◽

Fulvic Acid ◽

Metal Ion ◽

Ion Binding ◽

Metal Ion Binding

Download Full-text

Determination of metal ion binding parameters for humic substances

Journal of Electroanalytical Chemistry ◽

10.1016/s0022-0728(00)00186-8 ◽

2000 ◽

Vol 488 (1) ◽

pp. 1-16 ◽

Cited By ~ 25

Author(s):

Raewyn M. Town ◽

Montserrat Filella

Keyword(s):

Humic Substances ◽

Metal Ion ◽

Ion Binding ◽

Binding Parameters ◽

Metal Ion Binding

Download Full-text

Fluorescence Analysis of Cu(II), Pb(II) and Hg(II) Ion Binding to Humic and Fulvic Acids

Materials Science Forum ◽

10.4028/www.scientific.net/msf.851.135 ◽

2016 ◽

Vol 851 ◽

pp. 135-140 ◽

Cited By ~ 3

Author(s):

Vojtěch Enev ◽

Irena Türkeová ◽

Jana Szewieczková ◽

Leos Doskocil ◽

Martina Klučáková

Keyword(s):

Humic Substances ◽

Stability Constants ◽

Metal Ion ◽

Fluorescence Analysis ◽

Fulvic Acids ◽

Ion Binding ◽

Conditional Stability ◽

Metal Ion Binding ◽

The Stability ◽

Conditional Stability Constants

Abstract. The aim of this work was to study molecular and quantitative aspects of metal ion binding to humic substances (HS). The object of our study was characterization of two standards of humic substances (Elliott Soil standard HA 1S102H and Elliott Soil standard FA 2S102F). All samples of IHSS standards HS were characterized by elemental analysis (EA), ultraviolet-visible spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR) and steady-state fluorescence spectroscopy. Chemical parameters on the complexation of Cu (II), Pb(II) and Hg(II), including the conditional stability constants and the percentage of fluorophores participating in the complexation, were estimated by the modified Stern–Volmer equation. The stability constants (log Ka) of Me(II)–ESHS complexes range from 3.70 to 5.15 in the order: Hg–ESHA>Cu–ESHA>Pb–ESHA>Cu–ESFA>Pb–ESFA. With respect to the ESHA, ESFA, which showed the smallest contents of O-containing functional groups (e.g. hydroxyl, carbonyl, ester, especially carboxyl groups on the aromatic ring) and the lowest humification degree, the ESFA was characterized by much smaller stability constants. Our findings suggest that soil HS belongs to class of important organic ligands for complexation with heavy metal ions and may significantly affect the chemical forms, mobility, bioavailability and ecotoxicity of heavy metals in the soil environment.

Download Full-text