TIME VARIATION OF SOME CHEMICAL AND MICROBIOLOGICAL OIL POLLUTED SOIL PROPERTIES UNDER BIO-REMEDIATION TECHNOLOGY ACCELERATED BY BACTERIAL INOCULUM PUBLISHEDMihaela LUNGU, R. LĂCĂTUŞU, O. ANICĂI, C. ANA, Rodica Doina LAZĂR, Nineta RIZEA, Mihaela Monica ALDEA, Venera Mihaela STROE, Tatiana PASCU PASCU
Researches have been carried on in order to elaborate a platform for oil pollution risk assessment, in the framework of the PN 2 Project No.11036/2007 BIOREGIS. a bio-remediation technology accelerated by bacterial inoculum has been applied on a former petroleum park, at Sfinţii Voievozi, Dâmboviţa County. The experiment mainly approaches bio-electro-kinetic remediation techniques to extract organic pollutants from soil by stimulating the direct movement of the contaminants and of the bacteria towards the carbon source pollutants. The technology is insufficiently investigated, especially as in situ real experiments, due to the complexity of the physical and chemical changes undergone by soil and by the contaminants.Some chemical and micro-biological changes are studied in the present paper, in order to asses the soil evolution under the bio-electro-kinetic remediation techniques impact. Laboratory analyses were performed to determine the soil properties, as follows: the organic carbon by the Walkley-Black method modified by Gogoaşă, total nitrogen by the Kjeldahl method, nitrates – potentiometric determination with electron-selective electrode, mobile phosphorus and potassium contents, extracted in ammonium acetate-lactate and colorimetric respectively flamphotometric determinations, soil reaction (pH), potentiometric determination in 1:2,5 aqueous suspension and soluble salts contents, conductometric determination in aqueous extract. Microbiological analyses were performed as well, namely quantitative and taxonomic determinations of bacterial micro flora, using Topping growing medium.The evolution of the soil chemical and microbiological properties has been studied, by sampling and laboratory analyses carried out at different time intervals. Under these circumstances the variation of the soil macro-elements contents had a generally increasing tendency and strong fluctuations, especially influenced by the groundwater level variation due to rainfall. The nitrates content is alarming as it reaches over 900 mg·kg -1 , more than 15 times higher than the normal content in vegetable growing soils. The reaction remained slightly alkaline throughout the experiment, with a slight decreasing tendency in the control samples due to ammonium nitrate fertilization. The pH values at the end of the experiment were smaller than the initial ones in all three sampling points.All the samples present slight and moderate salinisation; chlorides predominate. The salinisation intensity alternates between slight and moderate. Sodium chlorine clearly predominates in the soluble salts composition.An increase of the total microorganisms number is noticed, respectively bacteria, reported per gram of dry soil, towards the end of the monitoring period.
organic contaminants, bio-electro-kinetic remediation, soil chemical properties, soil micro-biological properties