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| Titel |
In situ remediation of Cd, Cu and Zn contaminated topsoils by different amendments |
| VerfasserIn |
Thomas Hanauer, Stephan Jung, Diedich Steffens, Levan Navrozashvili, Besik Kalandadze, Peter Felix-Henningsen |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250045592
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| Zusammenfassung |
| Trace metal contamination of soils in the vicinity of metal mines and industrial sites is very
common in industrial countries. Due to the extent of these contaminations polluted most soils
cannot be cleaned through conventional remediation techniques (e.g. dig and dump). Thus
the most appropriate option to minimize the hazard of transferring metals into the
food chain is an in situ immobilization of these elements by amendments. In situ
immobilization does not mean a reduction of the total metal content, but rather
enhancement of the natural attenuation mechanisms concerning metal mobility and
bioavailability or the formation of new inorganic or organic phases. It decreases exposure
by one or a combination of different processes such as sorption, redox reaction,
precipitation, ion exchange, complexation, excesses of competing elements and
humification
Within the framework of a research project between the Justus Liebig University of
Giessen and the Ivane Javakhishvili University Tbilisi State University, research has
been conducted on in situ immobilization of Cd, Cu and Zn in the A-horizon of
Kastanozems contaminated from non-ferrous metal mining, in Southeast Georgia.
These soils are characterized by high contents of clay, Fe- and Mn-oxides, organic
matter and also a neutral pH, resulting in a high cation exchange capacity. In spite of
that, the examined soil show high contents of mobile metals exceeding action and
trigger values due to the German Federal Soil Protection and Contaminated Sites
Ordinance.
Aim of the study was the reduction of the mobile fractions of Cd, Cu and Zn along with
the reduction of plant uptake. Four different amendments were tested in order to achieve these
goals: elementary Fe, a natural Georgian zeolith, Divergan® (a synthetic polymer) and a
Biochar product. The amendments were mixed in different concentration levels to 4 kg of the
soil and incubated in a climate chamber. After five weeks a significant decrease in
the NH4NO3 extractable metals were measured in comparison to the control. The
Divergan® amendment lowered the Cd content even below the detection limit. The other
amendments reduce the Cd content significantly but not below the action value. The Cu
content was significantly reduced with the Fe amendment (minus 19%) and the
Divergan® amendment (minus 77%). The Zn content was significantly reduced by all
amendments.
Furthermore, Spinacia oleracea L., Brassica napus L. and Triticum aestivum L. were
grown in succession in the pots. The control pots showed severe toxic chlorotic symptoms on
leaves and growth depression for S.olercea and B.napus but not for T.aestivum. The
amendment pots all showed more or less severe chlorotic symptoms up to none
symptoms, but growth increased in all treatments. The dry weight increased within the
amendment pots (up to >20 fold in case of B.napus) and metal concentrations in
plant tissue decreased in comparison to the control pots (minus 85% in case of
Cd and B.napus). In conclusion Divergan® worked best in reducing the mobile
fraction as well as plant uptake of Cd, Cu and Zn in the contaminated Kastanozem. |
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