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| Titel |
The role of particle-size soil fractions in the adsorption of heavy metals |
| VerfasserIn |
Saglara Mandzhieva, Tatiana Minkina, David Pinsky, Аbdulmalik Batukaev, Valeriy Kalinitchenko, Svetlana Sushkova, Viktor Chaplygin, Zaurbek Dikaev, Viktor Startsev, Serojdin Bakoev |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100977
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| Publikation (Nr.) |
 EGU/EGU2014-17007.pdf |
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| Zusammenfassung |
| Ion-exchange adsorption phenomena are important in the immobilization of heavy metals
(HMs) by soils. Numerous works are devoted to the study of this problem. However, the
interaction features of different particle-size soil fractions and their role in the immobilization
of HMs studied insufficiently. Therefore, the assessment of the effect of the particle-size
distribution on the adsorption properties of soils is a vital task. The parameters of Cu2+, Pb2+
and Zn2+ adsorption by chernozems of the south of Russia and their particle-size
fractions were studied. In the particle-size fractions separated from the soils, the
concentrations of Cu2+, Pb2+, and Zn2 decreased with the decreasing particle size. The
parameters of the adsorption values of k (the constant of the affinity)and Cmax.(the
maximum adsorption of the HMs) characterizing the adsorption of HMs by the southern
chernozem and its particle-size fractions formed the following sequence: silt > clay
> entire soil. The adsorption capacity of chernozems for Cu2+, Pb2+, and Zn2+
depending on the particle-size distribution decreased in the following sequence: clay
loamy ordinary chernozem clay loamy southern chernozem> loamy southern
chernozem> loamy sandy southern chernozem. According to the parameters of the
adsorption by the different particle-size fractions, the heavy metal cations form a
sequence analogous to that obtained for the entire soils: Cu2+ ≥ Pb2+ > Zn2+.
The parameters of the heavy metal adsorption by similar particle-size fractions
separated from different soils decreased in the following order: clay loamy chernozem>
loamy chernozem> loamy sandy chernozem. The analysis of the changes in the
parameters of the Cu2+, Pb2+, and Zn2+ adsorption by the studied soils and their
particle-size fractions showed that the extensive adsorption characteristic – the maximum
adsorption (Cmax.) – is a less sensitive parameter characterizing the adsorption
capacity of the soils than the intensive characteristic of the process – the adsorption
equilibrium constant (k).The ratio between the content of exchangeable cations
displaced from the soil adsorbing complex (SAC) into the solution and the content of
adsorbed HMs decreased with the increasing concentration of adsorbed HMs. These
values could be higher (for Cu2+ and Pb2+), equal, or lower than 1 (for Zn2+) and
depend on the properties of HMs. At the first case, this was due to the dissolution of
readily soluble salts at low HM concentrations in the SAC. In the latter case, this was
related to the adsorption of associated forms HMs and the formation of new phases
localized on the surface of soil particles at high HM concentrations in the SAC.
Soil solution equilibrium (SSE) accords to the soil fine fraction composition. SSE
thermodynamics causes the ratio of free and associated forms of ions and ion’s activity in soil
solution influencing composition, concentration and adsorption of HMs salts by
SAC.
This study was supported by the Russian Foundation for Basic Research, project no.
12-05-33078,14-05-00586_a, grant of President of MK-6448.2014.4 |
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