Approaches to metal speciation analysis in natural waters

2005 ◽  
pp. 55-73 ◽  
Author(s):  
G. M. P. Morrison
Keyword(s):  
Natural Waters ◽  
Metal Speciation ◽  
Speciation Analysis

Dynamic features of speciation analysis by adsorptive stripping techniques

2010 ◽  
Vol 7 (3) ◽  
pp. 242 ◽  
Author(s):  
Raewyn M. Town ◽  
Herman P. van Leeuwen
Keyword(s):  
Ligand Exchange ◽  
Natural Waters ◽  
Environmental Fate ◽  
Metal Speciation ◽  
Speciation Analysis ◽  
Dynamic Features ◽  
Natural Systems ◽  
Surface Active ◽  
The Stability ◽  
Kinetic Features

Environmental context.The environmental fate and bioavailability of metal ions in natural waters is determined by their thermodynamic stability and kinetic features, both of which are distributed. Competing ligand exchange – adsorptive stripping (CLE-AdS) is a technique that measures a certain portion of these complexes as determined by the stability of the selected competing ligand and the dynamic features of the sample complexes that remain following ligand exchange. Exploitation of CLE-AdS to determine a spectrum of sample complexes requires insight into its thermodynamic and kinetic windows. Abstract.The kinetic features of the accumulation step of competing ligand exchange – adsorptive stripping (CLE-AdS) in metal speciation methodology are elaborated. During the adsorptive accumulation process, the flux of the surface active complex MLad towards the electrode may be modified by the coupled conversions of ML and M into MLad. An immediate consequence is that the accumulation flux of MLad can be greater than that corresponding to its mere bulk concentration: a labile ML contributes fully to the MLad accumulation, and a further flux enhancement can arise if ML is more mobile than MLad (DML > DMLad). Applying the conventional lability criterion, we present a framework for interpretation of CLE-AdS measurements in the presence of kinetic contributions from sample ML to the adsorptive accumulation of MLad. Measured accumulation fluxes for a kinetic case are well described by the presented theoretical framework. The dynamic analysis provides the basis for exploitation of CLE-AdS over a wider kinetic window than has been used to date. Consideration of the dynamics of sample species during the adsorptive accumulation step is fundamental for interpretation of metal speciation by CLE-AdS in complex natural systems that contain a distribution of complexes of different stability, lability, and mobility.

scholarly journals Speciation Analysis of Heavy Metals in Natural Waters: A Review

2001 ◽  
Vol 84 (6) ◽  
pp. 1763-1769 ◽  
Author(s):  
Konstantinos Fytianos
Keyword(s):  
Heavy Metals ◽  
Potential Risk ◽  
Natural Waters ◽  
Metal Speciation ◽  
Chemical Species ◽  
Speciation Analysis ◽  
Analytical Procedures ◽  
Detailed Presentation

Abstract Metal speciation in natural waters is of increasing interest and importance because toxicity, bioavailability, environmental mobility, biogeochemical behavior, and potential risk in general are strongly dependent on the chemical species of metals. This paper provides an overview of the need for speciation of heavy metals in natural waters, the chemical and toxicological aspects of speciation, and the analytical procedures for separation and the different techniques for final determination that are used today. The trends and developments of speciation are also discussed. Finally, the case of chromium (Cr) was selected for a detailed presentation because the speciation of this metal has attracted a great deal of interest in view of the toxic properties of Cr(VI).

Contribution of organic arsenic species to total arsenic measurements using ferrihydrite-backed diffusive gradients in thin films (DGT)

2012 ◽  
Vol 9 (1) ◽  
pp. 55 ◽  
Author(s):  
Heléne Österlund ◽  
Mikko Faarinen ◽  
Johan Ingri ◽  
Douglas C. Baxter
Keyword(s):  
Thin Films ◽  
Natural Waters ◽  
Arsenic Speciation ◽  
Inorganic Arsenic ◽  
Speciation Analysis ◽  
Arsenic Species ◽  
Future Studies ◽  
Organic Arsenic ◽  
Arsenic Determination ◽  
Diffusive Gradients

Environmental contextBoth the mobility and toxicity of arsenic in natural waters are related to the aqueous species distribution. Passive sampling using ferrihydrite-backed diffusive gradients in thin films (DGT) devices has in previous studies been characterised to measure labile inorganic arsenic, and the possible contribution of organic species has been disregarded. This study shows that the two most prevalent organic arsenic species might be included in DGT measurements, which should be taken into consideration when evaluating DGT data in future studies. AbstractIn previous publications discussing arsenic determination using ferrihydrite-backed diffusive gradients in thin films (DGT) devices, organic arsenic forms have been disregarded, even though it is known that the two most prevalent in natural waters, dimethylarsinate (DMA) and monomethylarsonate (MMA), may adsorb to ferrihydrite and thereby be included in the measurement. In this work the accumulation of DMA and MMA, as well as inorganic arsenite and arsenate, to ferrihydrite-backed DGT devices was investigated. It could be demonstrated that MMA, and under acidic conditions also DMA, adsorbed to the binding layer and might therefore contribute to the total mass of measured arsenic. Diffusion coefficients were measured for all four species to enable quantification of DGT-labile concentrations of organic and inorganic arsenic. Elution of the analytes from the ferrihydrite binding layer was performed using 1 mL of 1 M NaOH to facilitate arsenic speciation analysis using chromatographic separation. Average recovery rates were between 87 and 108 %. This study shows that the contribution of DMA and MMA to the total accumulated mass must be taken into consideration when evaluating DGT data in future studies.

Metals speciation in Arctic lake under pollution impact (1980-2019): in-situ measurements, experimental estimates, model calculations

2020 ◽  
Author(s):  
Marina Dinu
Keyword(s):  
Membrane Filtration ◽  
Natural Waters ◽  
Metal Speciation ◽  
Wide Spectrum ◽  
Material Balance ◽  
Acidity Constant ◽  
Model Calculations ◽  
Membrane Pore ◽  
Arctic Lake ◽  
The Impact

<p>An important fundamental block in the geochemical studies is the evaluation of the equilibrium distribution of metals in water and the influence of environmental conditions on the spetiation. It is important to understand the difference between the behavior of nanoparticles, dissolved particles, colloid particles, and suspended particles. The research deals with study and assess of geochemical processes of metal speciation in Arctic lake in the zone of metallurgical waste and other areas, where natural processes prevail. Consecutive and parallel membrane filtration methods were used to compare of the results of water analysis in the Imandra lake. The membrane pore sizes were: 8 µm, 1.2 µm, 0.45 µm, 0.2 µm. The following filterates characteristics were used: (microfiltration-based) mechanical suspension and oxidized contaminants (>8 μm, 1.2 μm, 0.45 μm, 0.2 μm, 0.1 μm); and (ultrafiltration-based) colloid, bacteria, viruses, etc (less than 0.1 μm).</p><p>Industrial effluents lead to the formation of higher concentrations of elements (Ni, Cu, Pb) in their labile forms as were found. In the wastewater-mixing zone, the concentrations of most elements are evenly distributed in depth. In areas that are more distant, there was a significant increase in the concentration of elements in the near-bottom horizon in comparison with the surface waters (Fe by more than 3 times). The obtained results showed that numerous elements had diverse distribution by speciation in the point located closer to the source of wastewaters. This indicates a significant influence of adsorption process on the system balance by such elements as Fe, Cu, and rare earth elements.</p><p>The impact of the regional geochemical and anthropogenic speciation and the possible influence of the climatic factor on the metals speciation were showed.   The authors did not have data on the metals speciation in the chosen points for the whole period of monitoring from 1980 until present. However, ElementPhasMigration (certificate 2017662509, Dinu M.I.) software was used to calculate the shares of labile and non-labile metal speciation during the years of the highest pollution (beginning of the 1990s) and during the current period of the ecosystem restoration.    </p><p>The software used mathematic modeling of chemical reactions happening in the natural waters and was based on the main laws of analytical and physical chemistry: material balance equation, equilibrium constant, equations of electrical neutrality, equations of proton balance, and competing reactions.</p><p>On the one hand, the initial data comprised a significant number of physicochemical parameters of the environment (more than 10 metal ions, рН, content of organic and non-organic anions, etc.). On the other hand, it included diverse mathematical tools for consecutive calculation of acidity constant of organic acids, conditional constants of complexes stability, the share of strong and weak acids in the system, etc. The software solved the tasks on the evaluation of the metal speciation depending on the physical and chemical parameters of the environment and provided the data on the balance speciation of a wide spectrum of elements in the system. The final stage of the calculations included the results verification with the field data.      Financing RFS 18-77-00018</p>

scholarly journals A tribute to Jacques Buffle: founding father of dynamic metal speciation analysis

2009 ◽  
Vol 43 (19) ◽  
pp. 7157-7158
Author(s):  
Herman P. van Leeuwen ◽  
Kevin J. Wilkinson ◽  
Raewyn M. Town
Keyword(s):  
Metal Speciation ◽  
Speciation Analysis ◽  
Founding Father

“Enological” Metal Speciation Analysis

1998 ◽  
Vol 60 (2) ◽  
pp. 134-142 ◽  
Author(s):  
Zoltán Murányi ◽  
Lajos Papp
Keyword(s):  
Metal Speciation ◽  
Speciation Analysis

Dynamic Speciation Analysis of Heterogeneous Metal Complexes with Natural Ligands by Stripping Chronopotentiometry at Scanned Deposition Potential (SSCP)

2004 ◽  
Vol 57 (10) ◽  
pp. 983 ◽  
Author(s):  
Raewyn M. Town ◽  
Herman P. van Leeuwen
Keyword(s):  
Metal Complexes ◽  
Humic Substances ◽  
Metal Binding ◽  
Metal Speciation ◽  
Speciation Analysis ◽  
Deposition Potential ◽  
Stripping Chronopotentiometry ◽  
Determination Of Parameters ◽  
Apparent Stability

Stripping chronopotentiometry at scanned deposition potential (SSCP) allows chemical heterogeneity in metal speciation to be unambiguously identified. In the labile regime, use of the Freundlich binding isotherm allows straightforward determination of parameters to describe the apparent stability and heterogeneity of metal complexes with humic substances. The extent of heterogeneity of metal binding by several humic substances follows the order Cu(ii) >> Pb(ii) > Cd(ii). The lability of metal complexes decreases from the foot to the top of the wave, and the greater the degree of heterogeneity, the more readily lability is lost. In the kinetic current regime, the Koutecký–Koryta approximation allows an expression to be obtained for the SSCP wave that provides a good estimate of the experimental data for metal complexes with moderate degrees of heterogeneity.

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