RESEARCH OF HETEROTROPIC BACTERIA SHARE AT DESTRUCTION OF CLAYS AND
ROCKS IN BIOFORMING OF AL GELS AT LOCALITIES AT PODLUZI (SOUTHERN MORAVIA,
CZECH REPUBLIC)
Libuse Durdova 1 , Iveta Styriakova 2
X Institute of Hydrodynamics, Academy of Sciences of the Czech Republic, Pod Patankou 5/30, 16612
Prague, Office Brno: Krenova 52, 602 00 Brno, Czech Republic, E-mail: durdlib@volny.cz
1 Department of Biotechnology, Institute of Geotechnics of the Slovak Academy of Sciences,
Watsonova 45, 043 53 Kosice, Slovakia, E-mail: bacil@saske.sk
At the edge of wellfield Podluzi at the Quatternary of the Morava river with exploitation of drinking groundwater (60l/s) were drilled in 1988-1990 monitoring borewells of indication system VIS - VIS 21.
Groundwater at wellfield itself is of hydrocarbonate type and is exploited from 38 hydrologic wells (HV
2A- HV 40) and at northern part of wellfield there was found increase of sulphate concentration (even over 300 mg/l). At majority of monitoring boreholes VIS the concentration of sulphates is 60-100 mg/l, only at the northern part at VIS 20 a VIS 21 sulphate concentration is 350 –550 mg/l. At all hydrologic wells and VIS borewells there was found to the depth 10 m petrgrapic profil: Holocene flood soil,
Pleistocene sand and gravel and Neogene bedrock clay. Monitoring VIS borewells had to indicate and to be used for sanitary pumping of contamination from oil field, which was never started.
After 15 years was verified in VIS borewells layer of sediments and sludges as tick as 2 m.
Exceptional is borewell VIS 21 without sediments. Sediments contained precipitates with Fe minerals
(by X-raxy verified: goethite, magnetite, pyrite, lepidocrockite, greygite), and elemental Al (spots verified by electron microprobe from tens to several hundreds micrones), white alumogels (49,6%
Al
2
O
3
.nH
2
O) at which was verified by 27 Al MAS nuclear magnetic resonance presence of ε –Keggin polyoxocation AlO
4
Al
12
(OH)
24
(H
2
O)
12
7+ (aq) [Al
13
]. These hydrophilic colloids composed of Al
13 nanoclusters can on their surface accumulate heavy metal cations.
We have used for processes simulation at natural conditions at Morava river watershed natural clays for explanation of genesis of Al rich precipitates and we had affected them for 3 months by solutions of several chemical composition, different pH, and concentration of heterotropic bacteria. While pH, eletrolytical conductivity, starting and final Al concentration was monitored, we have used the following media:
- abiotic model solution with composition adequate to water from VIS borewells from Podluzi
(extracted from VIS 20, VIS 21)
- biotic model solution with composition adequate to water from VIS borewells from Podluzi with remarkable enrichment by organic matter and concentration of heterotropic bacteria gained from cultivation from gels and sludge from borewells VIS
- solution with composition adequate to water from VIS borewells from Podluzi, but with autochtonic bacteria and with remarkable enrichment by organic matter
The direction of these experiments with biodestruction of clay and pH change in medium is depending on the carbon sources, as the breakdown of carbon matter is resulting in acidification. The breakdown of aminoacids and organic acids is leading to an decrease in pH and then aluminium from silicate particles is mobilised into the solution. Electron dispersion X-ray analysis (EDS) studies of the heterotropic bacteria showed the aluminium was associated with cell walls, and appeared to accumulate specifically within exopolysaccharides (gels, EPS). It has been suggested that EPS production is a strategy to neutralise the toxic effects of aluminium on bacteria. The formation of Al particles within EPS also influences other bacterial ability of destruction of the clay and silicate particles of rocks.