C - Lublin
C - Lublin
C - Lublin
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BIODEGRADATION OF ORGANIC CHEMICALS IN SOIL IN THE<br />
PRESENCE OF ACTIVATED CARBON<br />
Vasilyeva G.K., Strijakova E.R., Subocheva S.A., Nikolaeva S.N.<br />
INTRODUCTION<br />
One of the reasons for low effectiveness of soil bioremediation is the high<br />
toxicity of chemical contaminants to microbes and plants. The amendment to soil<br />
with some natural adsorbents can reduce chemical toxicity. Activated carbon (AC)<br />
is one of the best adsorbents for many organic chemicals because of its<br />
hydrophobicity, high specific surface, and microporous structure.<br />
The objective of this research is to demonstrate the reduction in toxicity of<br />
three classes of pollutants (chloroanilines, polynitroaromatics and polychlorinated<br />
byphenils) and to study mechanisms of their accelerated biodegradation and<br />
detoxification in soil in the presence of activated carbon.<br />
RESULTS AND DISCUSSION<br />
Laboratory experiments with 3,4-dichloroanilines (DCA), 2,4,6-tirinrotoluene<br />
(TNT) and polychlorinated biphenyls (PCB) were conducted with several types of<br />
soil from Russia and the USA. Soil samples were artificially or naturally<br />
contaminated with these chemicals with the initial concentrations from 500 to<br />
15000 mg/kg. Some samples were inoculated with microorganisms able to degrade<br />
these chemicals (e.g. Pseudomonas aeruginosa reducing TNT and some<br />
commercial rizosphere microorganisms degrading PCB) or with strains able to use<br />
these chemicals as a sole source of carbon, nitrogen and energy (Pseudomonas<br />
denitrificans and other strains growing on DCA). A fractionated analysis of the<br />
soil was carried out to determine water extractable, solvent extractable and<br />
unextractable (bound) fractions of the chemicals. HPLC, GC and chromatomassspectrometer<br />
were used for analytical determination of the chemicals and their<br />
metabolites in soil.<br />
It was demonstrated that these microorganisms could grow in highly<br />
contaminated soils and transformed the chemicals only after soil amendment with<br />
appropriate brand and dose of activated carbon. The adsorbent maintained low<br />
toxic concentrations of the chemicals in soil solution to degrading microorganisms<br />
and plants. Meantime the adsorbed chemicals were mostly available to degrading<br />
microorganisms, however the rates of degradation of the chemical residues were<br />
slower than those at the beginning of the process. Nevertheless the toxicity of the<br />
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