the effect of phytoremediation on the reduction of heavy metals in greenhouse scale

In recent years, the issue of heavy metal contaminated soils is one of the biggest environmental problems. the environmental protection agency (epa) identifies nickel and lead as two of the most important environmental pollutants. the phytoremediation of metal-contaminated soils is a low cost method for soil remediation. this study was conducted to investigate the status of soil contamination in gachsaran oil refinery using the pollution coefficients, the degree of contamination (dc), and the modified degree of contamination (mcd) indices. in order to evaluate the efficacy of alfalfa for phytoremediation of the lead and nickel from the oil-contaminated soil, transfer coefficients, bio concentration, and bioaccumulation factors were used. four areas ranging from 0 to 500 meters, 500-1000 meters, 1000-1500 meters, and 1500-2000 meters were selected from the polluted site. then, five soil samples were collected from each area. the inductively coupled plasma‐optical emission spectroscopy (icp-oes) was used to determine heavy metals. the analysis of the environmental indicators of the studied area showed a significant degree of contamination for nickel and lead. due to the higher biostatic and bioaccumulation factors of nickel (0.3 and 0.31, respectively) compared to those of lead (0.09 and 0.11, respectively), alfalfa plant showed greater ability in refining nickel contaminant both in aerial and root organs. conclusion: in sum, the findings indicated higher ability of alfalfa plant in the phytoremediation of nickel than lead in oil-contaminated soil. finally, the alfalfa is suggested for purifying other contaminants.