The soil contaminated with petroleum products must be excluded from the crops and treated to reclamation processes. Natural processes of decomposition of hydrocarbon compounds go very slow, so it is necessary to use bioaugumentation or stimulation in order to accelerate the return of the soil to high culture. In this study the effect of hydrogen peroxide on the process of cleaning soil strongly contaminated with pertochemicals was investigated. For this purpose, a pot experiment lasting 60 days was carried. The dynamics of changes in the population of fi lamentous fungi, yeasts and bacteria were examined and also content of aliphatic hydrocarbons (n-alkanes), monoaromatic and polycyclic aromatic hydrocarbons (PAHs). Experimental use of hydrogen peroxide in the process of biodegradation of petroleum compounds assisted in the analyzed soil led to an increase of the number of grampositive bacteria during the test. Stimulation of oil products biodegradation by hydrogen peroxide also increased by 35% decomposition effi ciency of aliphatic hydrocarbons (C8-C40) and about 50% PAH's in comparison to control samples without hydrogen peroxide. There was no infl uence of hydrogen peroxide on the content of monoaromatic hydrocarbons (BTEX) with respect to controls, although in the end of experiment, the total concentration decreased by about 50% compared to the initial content.Keywords: soil, remediation, petrochemicals, hydrogen peroxide. INTRODUCTIONCrude oil products (petrochemicals) may transform in the environment as a result of physico-chemical as well as biological processes. Attenuation (natural processes to decrease concentrations of contaminants in soil) consists in degradation of petrochemicals by autochthonic microorganisms which use them as a main source of carbon . The process may take even several hundred years 5. The fi nal attenuation products are typically carbon dioxide, inorganic substances and biomass.Biodegradation of soil-contaminating petrochemicals depends on site specifi c conditions such as physical and chemical properties of soil, concentration and structure of the petrochemical contamination, concentration of biogenic compounds, temperature, oxygen content, humidity, soil reaction and activity of the microbial consortia 6, 7. Soil bioremediation processes may be enhanced by the use of such techniques as bioaugmentation and/or biostimulation 5, 8 with oxygen or/and correcting soil reaction and enrichment with biogenic compounds facilitating the development of autochthonic microbial communities.The rate of the biodegradation process is to a large extent determined by oxygen delivery to the soil. It can be applied either directly to subsurface (oxygen injection) or in a form of chemical compounds such as ozone or hydrogen peroxide. Due to its properties and decomposing to yield only oxygen and water, hydrogen peroxide is considered environmentally friendly powerful oxidizer, often applied in chemical clean-up processes of soils with pH 3-5 (Fenton reaction) 9, 10, 11, 12. Reactive forms of oxygen r...

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The activity of soil microorganisms affects soil fertility and structure, what leads to satisfactory crop yields, thanks to changes in the decay of organic matter. Their activity may be impaired as a result of application by farmers both fertilizers and pesticides. The degradation of cellulosic biomass represents an important part of the carbon cycle within the biosphere. Cellulolitic microorganisms are responsible for this decomposition, as they produced the enzymes of the cellulase complex. The aim of the study was to compare the cellulolytic activity of soil with Roundup and modified using urea phosphate and / or manure. The pot experiment was conducted under laboratory conditions. The studied material was brown soil (pH of 5.5) fertilized with manure and/or urea phosphate. To each earthenware vase were fed 0.5 kg of the tested soil supplemented with 1% carboxymethyl cellulose. The cellulolytic activities of soil in different experimental variants were expressed in % of C using a colorimetric Petkov method. Modification of soil cellulolytic activity varied considerably depending on the additive manure and/or urea phosphate and Roundup. The lowest soil cellulolytic activity was observed in the presence of manure and urea phosphate, and the highest in the soil with manure and Roundup. The objects of Roundup independently of the other additives urea phosphate stimulate the activity of the cellulolytic microflora compared to objects containing only urea phosphate. The presence of manure in soil treated with Roundup clearly accelerated degradation of cellulose, what can be used in agriculture in the degradation of crop residues. The study shows that pesticides and fertilizers have a big impact on cellulolytic activity in soil. Changes in cellulolytic activity can be used as an ecological indicator of soil pollution level.

Abstract:The selection of bioremediation techniques is important for purifi cation of contaminated soil for agricultural use. Studies on soil contaminated with petroleum substances have indicated that the applied method of remediation has a bigger impact on the development of oat seedlings than the level of contamination. A yeast inoculum appeared to be a technique which was the friendliest to vegetation of oat.

The influence of Yarrowia lipolytica inoculum on biodegradation of hydrocarbons, and changes in microbiota composition in the soil contaminated with petroleum have been investigated. The material under study was contaminated clay soil, containing petroleum-derived substances at approximately 17 000 [mg/kg d. m.]. Microbiological analysis was carried out by the cultivation method and the content of individual hydrocarbons (n-aliphatic, BTEX and PAHs) was determined by the GC/MS method. The largest decrease of oil-derived substances, versus the control sample, was recorded at the beginning of the process. During the first 30 days, the yeast inoculation caused most effectively removal of n-aliphatic hydrocarbons and PAHs (approximately 80% reduction), however, the content of BTEX increased nearly three times. After 60 days of the process, PAHs concentration further decreased (by 40%), concentration of n-aliphatic hydrocarbons decreased a little, however the content of BTEX increased by 10%, compared to the initial concentration. Stimulating the biodegradation process with the yeast inoculum influenced the increase of the bacteria count, mainly Gram-positive, with simultaneous decrease of fungi number.