feasibility of sunflower (helianthus annus l.) plantation in low to moderately contaminated brownfields to achieve remediation objectives

phytoremediation has gained increasing attention in recent years because of its ability to clean up and redevelop brownfield sites. petroleum hydrocarbon-contaminated sites are among most prevalent industrial sites in iran as one of the top oil producers in the world, which are in great need of remediation to prevent associated environmental and human health risks. a greenhouse study was conducted to identify the tolerance of sunflower ( helianthus annus l.) and its growth parameters under various scenarios. additionally, remediation potential of sunflower in spiked soil with low to moderately gasoline-contaminated soil was evaluated. results indicated that sunflower is a tolerant plant species in low to moderately gasoline-contaminated soil with remarkable biomass establishment in contaminated soil and acceptable phytoremediation potential. sunflower was found to tolerate gasoline contamination up to the maximum applied concentration of 5000 mg/kg. however, sunflower biomass and height slightly decreased in presence of gasoline in soil which were not significant in most cases (p>0.05). significant reduction of gasoline under the influence of sunflower was obtained in all vegetated treatments when compared to non-vegetated treatments (p<0.05). phytoremediation effectiveness of sunflower did not vary significantly with increasing contamination level in soil (p>0.05). results of the present research indicated that gasoline content of soil cannot be considered as a controlling factor affecting phytoremediation potential of sunflower when soil is polluted with low to moderate levels of gasoline.  soil remediation with sunflower can be considered as a promising approach to manage moderately gasoline-contaminated sites.