Petroleum and petroleum-derived products can contribute to the inhibition of growth and development of plants. Soil contamination by these compounds either hampers or makes difficult the intake of water and mineral salts from the substrate, and also breaks a number of metabolic processes. As a result of the deficiency of chlorophyll and nutrients, the affected plants grow deformed roots, shoots, leaves, and flowers, and show numerous chloroses and necroses.
The objective of our research was to determine the effects of petrol, used engine oil, and diesel oil on select morphological parameters of Vicia faba L., and on the content of select nutrients and heavy metals in the leaves of plants. The effect of the bioremediation process initiated by biopreparation ZB-1 on the above-mentioned parameters was also determined. The analyzed plants were obtained from the Experimental Station of the University of Agriculture in Cracow, located in Mydlniki near Cracow. In June 2010, the soil placed in special containers was contaminated with petroleum-derived substances at a quantity of 6,000 mg per 1 kg of dry mass, by pouring it on the soil. Half of the objects were subjected to bioremediation. The evaluation of the morphology of plants and the structural elements of yield was made at the stage of technological maturity of broad bean seeds. The evaluation of heavy metals content was conducted using flame absorption spectrometry. The carbon, nitrogen, and sulphur content was determined in a Variomax CNS analyzer. The results of the experiment showed that diesel oil had the most adverse effects on the morphological parameters of plants. Engine oil caused a decrease in the nitrogen, carbon, and sulfur contents in the leaves of plants, but on the other hand this substance, like other petroleum-derived compounds, increased the content of most heavy metals. The effect of biopreparation was diverse and depended on the type of substance and on the analyzed parameter.
The conducted experiment showed that petroleum-derived substances continued to adversely affect the growth of plants even three years after soil contamination. Additionally, it increased the accumulation of harmful substances in the organs of plants which could, in turn, seriously impact the economy and human health. However, the intensity of the impact depends on the type of derivative. Bioremediation supported by the use of microorganisms is an advantageous solution that permits the improving of the growth parameters of plants, as well as offsetting the harmful effects of petroleum-derived products upon the majority of the analyzed elements.