Study phytoremediation of soils polluted with heavy metals and oil pollutants in agricultural lands

High concentration of oil contaminant in soils beside a devastated effect on ecosystems caused more uptakes of pollutants by plants and then entrance to human and other live organisms food chains. This phenomenon occured various diseases to humans and other organisms. Such pollutants can also cause problems for human health and the environment through ground water contamination as well. The existent methods for remediation of contaminated soil are often too costly and therefore cheaper methods for the decontamination of polluted soils can help refine and efficient use of such lands .One of the most modern and low cost techniques for remediation of contaminated soils is using plant (Phytoremediation). In addition to its lower cost, Phytoremediation is consistent with the nature and requires less equipment rather than the other methods. Due to the possibility of soil contamination caused by the war in the Persian Gulf in the border provinces of Iran and its survey to human health, plants and the environment, This project was carried out in two phases. In the first phase (the greenhouse phase) was determined the absorption rate of Lead and Cadmium and the ability of wheat and canola in remediation of the polluted and was designed as a factorial and completely randomized project with three replication. Factors included of : 1- Lead (Pb) at three levels( 0, 150, 500 mgkg-1 soil) and 2- cadmium (Cd) in three levels( 0, 3, 10 mgkg-1 soil). Then, in second phase (field phase), investigation on the possibility of using plants for remediation of soils polluted with heavy metals and petroleum contaminants in three agro-ecological areas of agricultural land in the provinces of Bushehr, Fars, Khuzestan and kohgyloyeh and boyerahmad with the treatment of different types of plant species (a crop, a vegetable and two pasture plants prevailing in each province) was implemented. For this purpose, physical and chemical properties, concentrations of heavy metals and petroleum contaminants in the soil before planting were analyzed. After harvest, concentrations of heavy metals and petroleum contaminants in the soil and plants (crops vegetative organs and seed, pasture vegetative organs and fruits and vegetative organs of vegetable products) were measured. Data obtained from experiments were statistically analyzed by SAS software. Greenhouse phase results showed that the effects of Lead, Cadmium and Lead and Cadmium interaction effects were significant on the concentration of Lead and Cadmium in straw and grain of wheat and Rapeseed at one percent level. The highest concentration of Cadmium in straw and grain of wheat and Rapeseed was obtained by 10 mg/kg of Cadmium and 500 mg/kg of lead treatment. It was also shown that the most lead concentration in wheat straw and seed obtained from 0 mg/kg of Cadmium and 500 mg/kg of Lead treatment whereas, it was in the treatment of 3 and 10 mg/kg Cadmium and 500 mg/kg Lead for Rapeseed. The field phase data showed that the pollution concentrations in vegetative and reproductive organs of plants were less than 0.1 mg/g in Fars Province, significant changes between different plants. In the case of heavy metals, the highest concentration of Cadmium was accounted in rice. Lead capture, was only observed in secale plant. Also, Nickel was more accumulated in vegetative organs of watermelon and secale respectively. Bushehr province results showed that among hydrocarbon contaminants, only Fluorene had significant changes in soils of the treatments, where castor plant had the most uptake of this material. Most Cadmium accumulation happened in the shoots and fruits of tomato plants by 175.5 and 105.3 micrograms per kg respectively. The highest concentration of Nickel was measured in castor and wheat seed by 1793.3 and 1245 micrograms per kg, respectively. Khuzestan province results showed that only the concentration of pyrene in melon seeds and Anthracene in vegetative organs of corn were more than 0.1 mg/kg whereas other oil pollutants (PAHs) were trace. The highest concentration of Vanadium was seen in the shoot of melon (3078 mg/kg). Also, the highest Nickel accumulations were measured in melon seeds and shoots by 14410 and 7328 micrograms per kg respectively. kohgyloyeh and boyerahmad results showed that the concentration of three oil pollutants; Fluorene Pyrene, Benzo [g, h, i] and Perylene showed significant difference at five percent level in soils. The highest mean concentrations of three contaminants were measured in soil that was planted by barley and their lowest concentrations were in stipa cultivated soil. Also, there was significant difference at one percent level between two heavy metals accumulation (Nickel and Cadmium) of plants in above soils. The largest accumulation of Nickel and Cadmium were seen in stipa and barley seed, respectively. Keywords: Phytoremediation, pollution, heavy metals, oil contaminants, wheat, canola, vegetable and pasture plants