engleski

IMPACT OF CRUDE OIL POLLUTION ON NITROGEN CYCLING AND DEHYDROGENASE ACTIVITY IN SOIL

Soil is a unique natural environment characterized by enormous abundance of microorganisms and complex interactions among microbial processes, soil properties and plant roots. Microbial abundance, diversity and activity are considered to be important indicators of soil health. Since the soil microorganisms respond to changes in their environment very fast, they are also considered as very useful indicators of unfavourable changes in soil caused by different pollutants. All phases of crude oil exploitation are accompanied by interventions and procedures hazardous to the environment. The main aim of the present study was to evaluate the microbial response to changes in soil caused by addition of crude oil and drilling fluids as well. The impact of these pollutants on abundance of microorganisms involved in nitrogen cycle as well as on dehydrogenase activity was studied. The field trial was set up on luvisol contaminated with crude oil and drilling fluids. Oilseed rape, winter wheat, winter barley were used as test plants. The results revealed marked variability in abundance of ammonifiers although pronounced regularity was less expressed. Low values of the most probable number of nitrifiers were determined in all trial treatments. Besides, the results clearly showed that nitrifiers were more susceptible to soil pollution than other groups. Among particular pollutants clear differences were found. Significantly lowest dehydrogenase activity was determined in the soil treated with the highest amounts of drilling fluids. The results revealed that microorganisms involved in nitrogen cycling strongly differ in their overall susceptibility to pollutants as well as in their particular response to crude oil and drilling fluid pollution. Detrimental effect of soil pollution on dehydrogenase activity was less expressed in comparison to particular groups of microorganisms involved in nitrogen cycle.

soil pollution; crude oil; nitrogen cycle; dehydrogenase activity

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