The aim of the research was to compare the effects of various petroleum products, biodiesel, diesel oil, fuel oil and unleaded petrol on soil dehydrogenases, and to evaluate biostimulation with compost and urea in the restoration of homeostasis of the soil contaminated with these products. The obtained results allowed for defining the weight of dehydrogenases in monitoring of the environment subjected to pressure from petroleum hydrocarbons. The studies were carried out under laboratory conditions for 180 days, and loamy sand was the soil formation used in the experiment. The petroleum products were used in the following amounts: 0, 2, 4, 8 and 16 g kg−1 DM of soil. Indices of the influence of the petroleum product and the stimulating substance on the activity of dehydrogenases were calculated. It was proved that the petroleum products affect soil dehydrogenases in various ways. Biodiesel, diesel oil and fuel oil stimulate these enzymes, while petrol acts as an inhibitor. Among the substances tested regarding biostimulation of soils contaminated with petroleum products, compost is definitely more useful than urea, and therefore, the former should be used for the remediation of such soils. Stimulation of dehydrogenases by compost, both in contaminated and non-contaminated soils, proves that it may accelerate microbiological degradation of petroleum-derived contaminants.

The main aim of our work was to evaluate the effect that the soil contamination with zinc, copper and cadmium has on the number of (CFU) Azotobacter, organotrophic bacteria and Streptomyces. The results of the experiment revealed their role in the CFU modification and the impact on the level of soil contamination with heavy metals. Organotrophic bacteria have a similar tolerance to the heavy metals as Streptomyces, since the lowest resistance characterizes the Azotobacter. The toxicity of the examined heavy metals can be ranked as follows (from the most sensitive to the least): Azotobacter>organotrophic bacteria>Streptomyces. It can be concluded that the succession of the microorganisms is determined by the soil fertility, which stimulates both the characteristics and biochemical transformations, that occur in it through the mechanisms involved in reducing the negative impact of the heavy metals on the number of microorganisms.Keywords: cadmium, copper, number of microorganisms, soil, zinc StreszczenieCelem pracy było określenie wpływu zanieczyszczenia gleby cynkiem, miedzią i kadmem na liczebność bakterii organotroficznych, promieniowców z rodzaju Streptomyces oraz bakterii z rodzaju Azotobacter. Wyniki eksperymentu wykazały wpływ testowanych metali ciężkich na liczebność badanych mikroorganizmów. Istotny okazał się zarówno poziom zanieczyszczenia jak i czas ekspozycji. Zarówno bakterie organotroficzne jak i promieniowce, wykazały podobny zakres tolerancji na metale ciężkie. Najmniejszą opornością charakteryzowały się bakterie z rodzaju Azotobacter. Wrażliwość drobnoustrojów względem badanych soli metali ciężkich można uszeregować w następujący sposób (od najbardziej wrażliwych): Azotobacter > bakterie organotroficzne > promieniowce z rodzaju Streptomyces. Liczebność mikroorganizmów glebowych uwarunkowana jest żyznością gleby, która działa stymulująco na przemiany biochemiczne w niej zachodzące poprzez mechanizmy warunkujące zmniejszenie negatywnego działania metali ciężkich.

Development of a standard dosimetric facility with protection against external radiation background for the metrological support of highly sensitive radiation monitoring devices in accordance with the requirements of international standards .