EFFECT OF POLLUTION WITH PETROLEUM ON SOME SOIL CHARACTERISTICS AND PLANT GROWTH

Petroleum products are complex mixtures of hundreds of hydrocarbon compounds. Petroleum has been recognized as a potential environmental contaminant. This research was undertaken to evaluate the effect of petroleum hydrocarbon on soil characteristics and seeds germination in arid lands. Results indicated that bulk density and real density of the polluted samples are relatively higher and lower respectively then the corresponding values of the unpolluted soils. Percent ages of the clay fraction obtained with and without removing the cementing agents showed high and low values for % clay fraction respectively. Low calcium carbonate content was found in the polluted samples as a result of solubilization effects of the petroleum products on calcium carbonate particles. ECe values were very high in the polluted samples (ECe = 28.6 - 82.5 dS/m) and very low in the unpolluted samples (ECe = 2.75 - 2.79 dS/m). Soluble calcium and sulphat ions were the dominant ions in the saturation extract of unpolluted soil samples. Organic matter contents were high (4.94%) in the polluted soil and Low in the unpolluted soil (0.54%). Soil polluted with hydrocarbon was very high (7.13-7.5%) in the unpolluted soil and very low (0.63-0.71%) in the polluted soil. Total elemental contents shows that the most important metals with regard to potential hazards in the contaminated soils, are Cr, Pb, and Ni. Other heavy metals indicated low to medium concentration either in petroleum polluted or the non polluted soils. The concentration of toxic elements in the tested soils could be derived from petroleum pollution and/or from it's chemical weathering particularly under the relatively low pH of the polluted soils. Results indicated no barley seed emergence after 14 days in the polluted soil even after several leaching to alleviate the high level of salt concentrations in the polluted soil. The data reflect the serious effects of petroleum products on the deterioration of soil characteristics which reflected on the emergence of barley seeds.