the effect of plants' growth at different densities on soil petroleum hydrocarbons remediation

abstract petroleum pollution is one of the most common and dangerous pollutions that is due to petroleum industries such as refineries, and consequently of oil pipes and tanks leak causing environmental pollutions. one of the newest born technologies in this area is phytoremediation, in which plants are used for decreasing of petroleum pollution. this technology is used for remediation of soil, underground and waste water pollution, because of low expenses and simple application. in this research bioremediation system by three plants barley, vetch and bean at three levels of density, with three replications in factorial experiments, randomized complete block design (rcbd) was used. in three steps of plant growth, concentration of total petroleum hydrocarbons (tphs) of soil was measured. statistical analysis showed that the amount of soil remediation had a direct relation with increasing plant density levels. the maximum remediation belonged to barley which in it's maximum density level, it reduced the amount of pollution up to 45.78%. generally, because of high resistance of barley to petroleum pollution and it’s ability for remediation of pollution, barley was recognized as the best plant among the evaluated treatments for remediation of petroleum polluted soils.