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| Titel |
Impact of non-ferrous metal mining on soil functions in the Mashavera valley, Georgia |
| VerfasserIn |
Thomas Hanauer, Levan Navrozashvili, Sylvia Schnell, Diedrich Steffens, Besik Kalandadze, Tengiz Urushadze, 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 |
250045590
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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. While extensive knowledge concerning the consequences
and distribution of metal contamination of soils and their effects on the food chain exists in
the western industrial states, such examinations of affected regions in the former Eastern Bloc
were either not conducted or not published.
The study area is located in the valley of the Mashavera River in the region of the town
Bolnisi, about 80 km south of the capital Tbilisi. It is a rural area with very fertile soils
(Kastanozems and Chernozems) of approx. 800 km2 in size. Cereals, vegetables and fruits are
grown for the conurbations of Eastern Georgia under irrigation due to the continental climate.
The river water used for irrigation is polluted with eroded mining waste from a Cu and Au
mine in the mountainous region of the middle reaches of the Mashavera River since end of
the 1970s. Furthermore, wastewater from a floatation plant, erosion material from floatation
waste deposits, and acid mine drainage has led to high concentrations of dissolved and
suspended sulfidic metals in the river water. It can be estimated that annual transfer of metals
by irrigation water is in the range of several g ha-1 in case of Cd and several kg ha-1 in
case of Cu and Zn. Most of the irrigated soils under different land use display a
strong enrichment of these metals. The concentrations of total amounts increase
with the intensity of irrigation with highest amounts in vegetable gardens. A high
proportion of the metals belong to the supply fraction, unspecifically and specifically
adsorbed and dissolvable in EDTA. Due to the narrow correlation of this fraction with
the mobile and potential-plant available fraction a high long-term risk potential
for the food chain exists. Although the soils display a high sorption capacity, the
metal concentrations at most of the investigated sites exceed the precaution and
trigger values defined in the German Federal Soil Protection and Contaminated Sites
Ordinance.
Food crops grown on these soils show Cu and Zn concentrations toxic for plant growth
and chlorosis as well as growth inhibitions can already be observed. European food safety
thresholds for Cd are partly exceeded, especially in vegetables like Spinacia olerachea
up to the 2.5 fold. Furthermore soil-microbial enzyme and respiration activity is
restrained by the high Cd, Cu and Zn concentrations. Due to this nutrient-cycle might be
disturbed.
Hence, actual ecological impact of the metal contamination in the Mashavera valley is
alarming and immediate measures (e.g. restriction of land use) are necessary to protect the
residents. |
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