OXIDATION OF HUMIC SUBSTANCES PRIOR TO THE DETECTION OF PCBs AND PAHs IN NATURAL WATERS BY FLUOROMETRY ON SOLID SORBENT

2005 ◽  
Vol 25 (5) ◽  
pp. 407-419 ◽  
Author(s):  
L. Belfatmi ◽  
S. Ait Lyazidi ◽  
M. Lamotte ◽  
Ph. Fornier de Violet
Keyword(s):  
Humic Substances ◽  
Natural Waters ◽  
Solid Sorbent

scholarly journals Interactions of hydrophobic metal complexes and their constituents with aquatic humic substances

2007 ◽  
Vol 4 (5) ◽  
pp. 323 ◽  
Author(s):  
Amiel Boullemant ◽  
Jean-Pierre Gagné ◽  
Claude Fortin ◽  
Peter G. C. Campbell
Keyword(s):  
Metal Complexes ◽  
Humic Substances ◽  
Natural Waters ◽  
Hydrophobic Interactions ◽  
Equilibrium Dialysis ◽  
Fulvic Acids ◽  
Suwannee River ◽  
Dissolved Humic Substances ◽  
Ph Range

Environmental context. Lipophilic metal complexes, because they can readily cross biological membranes, are especially bioavailable. However, in natural waters these complexes do not necessarily exist in a free state, i.e. they may bind to the organic matter (humic substances) that is present in natural waters. It follows that the in situ bioavailability of lipophilic metal complexes will tend to be less than that measured in simple laboratory experiments. Abstract. The ability of dissolved humic substances (HS: fulvic and humic acids) to complex cationic metals is well known, but their interactions with neutral lipophilic metal complexes are little understood. In the present study, we have examined the behaviour of two such complexes ( Cd  L 2 0 -->Cd L02: L = DDC = diethyldithiocarbamate, or L = XANT = ethylxanthate) in the presence of Suwannee River Humic and Fulvic acids. Interactions between the neutral complexes and the humic substances were assessed by excitation-emission matrix (EEM) fluorescence spectroscopy at pH 5.5 and 7.0, and by equilibrium dialysis experiments (500 Da cut-off). The EEM measurements were carried out by titrating the humic substances (6.5 mg C L–1) with Cd, in the absence or presence of ligand L (1 µM DDC or 100 µM XANT). Given the very high stability constants for the complexation of cadmium by DDC and XANT and the excess ligand concentration, virtually all (>96%) of the Cd added to the L + HS matrix was calculated to be present as the neutral Cd L 2 0 -->CdL20 complex over the entire pH range tested. For both humic substances, addition of DDC or XANT alone led to shifts in the fluorescence spectra at both pH values, indicating that the DDC– and XANT– anions likely interact by electrostatic or hydrogen bonding within the humic molecules. The subsequent addition of Cd to these L + HS systems resulted in a disproportionately large enhancement of the fluorescence intensities of individual EEM peaks, this fluorescence enhancement being only slightly decreased by the shift from pH 7.0 to 5.5. We interpret this enhancement as evidence that the two neutral complexes associate with the humic substances, presumably by forming ternary complexes (Ln-Cd-HS). Hydrophobic interactions between the humic substances and the neutral complexes may also contribute, but to a lesser extent, as demonstrated by partitioning calculations based on the lipophilicity of the neutral complexes. The association of the neutral complexes with Suwannee River Humic Acid was confirmed by dialysis experiments.

Study of chlorothalonil photodegradation in natural waters and in the presence of humic substances

Chemosphere ◽  
2002 ◽  
Vol 48 (9) ◽  
pp. 939-945 ◽  
Author(s):  
Vasilios A. Sakkas ◽  
Dimitra A. Lambropoulou ◽  
Triantafyllos A. Albanis
Keyword(s):  
Humic Substances ◽  
Natural Waters

Effect of Humic Substances on Americium (III) Retention onto Silica

1988 ◽  
Vol 127 ◽  
Author(s):  
Valerie Moulin ◽  
Denise Stammose
Keyword(s):  
Ionic Strength ◽  
Humic Substances ◽  
Safety Assessment ◽  
Natural Waters ◽  
Major Influence ◽  
Liquid Interfaces ◽  
Aquifer Systems ◽  
Humic Materials ◽  
Solid Liquid ◽  
Influence Of Ph

ABSTRACTThe migration/retention phenomena of radionuclides in geological systems are of great interest for the safety assessment of a nuclear disposal. Interactions at solid/liquid interfaces play a significant role in the speculation and transport of radionuclides in aquifer systems. Oxide surfaces and humic substances which occur in natural waters in large concentration ranges (from few mg/1 to several hundred mg/1) may have a major influence on radionuclides behaviour. For this purpose, studies have been carried out on a ternary system: oxide-humic substances-americium (III). The influence of pH, ionic strength and humic concentration on the adsorption of americium onto silica has been investigated. The ionic strength of the solution (0.1 and 0.01) has little effect on the americium adsorption. In the presence of humic materials, the fixation of americium is enhanced at low pH (pH<5) whereas, at higher pH (pH>5), the adsorption is lowered and dependent of humic concentration.

Interaction of ions of heavy metals and organic toxicants with humic substances in system ‘atmospheric precipitation - lysimetric waters - lake waters’ of the Reserve of the European Territory of Russia: climatic, technogenic, geochemical fact

2021 ◽  
Author(s):  
Marina Dinu
Keyword(s):  
Heavy Metals ◽  
Organic Matter ◽  
Humic Substances ◽  
Natural Waters ◽  
Atmospheric Precipitation ◽  
Organic Substances ◽  
Alkaline Lake ◽  
Autochthonous Organic Matter ◽  
Lake Waters ◽  
Lysimetric Waters

&lt;p&gt;The reactions of toxicants with organic substances of a humic nature are complex and depend on many geochemical factors. Differences in the mechanisms of the selected toxicants binding with organic natural substances of various natural waters - atmospheric precipitation, lake waters (acidic and alkaline), lysimetric waters are especially interesting. Due to significant concentration differences, features of functional groups and size distribution of components, the inactivation features of humic substances are selective and highly variable. We studied the waters of an acid lake near the city of Valday (Valday National Park, conditionally a background lake) and alkaline lake Valday (city of Valday, local technogenic influence). Near each lake there was a sediment collector (a container for collecting atmospheric precipitation) and a lysimeter (a container under the soil for collecting soil moisture) under the humus horizon (about 20 cm). Particular attention was paid to soil (lysimetric) waters with varying degrees of anthropogenic impact. We considered the behavior of a large group of heavy metals, as well as benzopyrene. To assess the composition and qualitative features of organic substances, gas chromatography-mass spectrometric methods of analysis were used. Chromatographic methods were used to assess the molecular weight distribution of the components. Possible reaction mechanisms were studied by IR spectral methods. Evaluation of the reactivity of organic substances was carried out by the methods of dynamic light scattering (zeta potential, MM, size) using the &quot;Zeta-sizer nano&quot;. In addition to humic substances in the waters, the contents of autochthonous organic matter were estimated, especially in an alkaline lake, which in some periods prevailed over humic ones. In addition to humic substances in the waters, the contents of autochthonous organic matter were estimated, especially in an alkaline lake, which in some periods prevailed over humic ones. For separation, exchange technique and fluorometric evaluations were used. We conducted research in the period 2015-2020, sampling was carried out in spring, summer, autumn. Thus, we studied the circulation (in miniature) of changes in the protective properties of humic substances, depending on a large number of factors.&lt;/p&gt;

Humic Substances of Natural Waters and Their Importance for Aquatic Ecosystems: a Review

2004 ◽  
Vol 40 (3) ◽  
pp. 102-110 ◽  
Author(s):  
P. N. Linnik ◽  
T. A. Vasilchuk ◽  
R. P. Linnik
Keyword(s):  
Humic Substances ◽  
Aquatic Ecosystems ◽  
Natural Waters
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