Effects of petroleum hydrocarbon pollution on plant's growth and efficiency of plants in hydrocarbon removal from soil

Phytoremediation is an emerging cost-effect green technology that can be a promising solution to remediate hydrocarbon-polluted soil. Screening native tolerant plant species for growing on weathered, petroleum hydrocarbon-contaminated soil is a key factor for successful phytoremediation which is considered here. This study investigated the effect of hydrocarbon pollution with initial concentration of 40000 mg/kg of soil on growth characteristics of 5 plant species; Alfalfa (Medicago sativa L.), Castor bean (Linum usitatissumum L.), Sunflower (Helianthus annuls L.), Flax (Linum usitatissumum L.), and Maize (Zea mays L.) (With / without organic fertilizers). Plant growth was monitored on days 10, 20, 30, 60, and 90. At the end of the experiment, soil samples in which plant species had grown well were analyzed for total petroleum hydrocarbons (TPHs) removal by GC-FID (eight soil samples with three replicates). Oil pollution depressed growth of surveyed plants significantly. Sun flower and maize had better growth characteristics than other species. Among the cultivated plants in hydrocarbon contaminated soil, maximum shoot height, root length, dry biomass of root and shoot were achieved in Sun flower (treatment I-25.5 cm), Castor bean (treatment H-26 cm), Sun flower (treatment I- 4.2 gr), and Maize (treatment E-2.6 gr), respectively. In addition, among the used organic fertilizers in this study, peat fertilizer had the best influence on growth parameters of plant species cultivated in hydrocarbon contaminated soils. Maximum phytoremediation potential was achieved in flax (63.87 percent removal). Flax reduced TPHs concentration by up to 35000 mg/kg of soil in a three-month experiment. Results confirmed that phytoremediation holds promise as an efficient treatment technology for TPHs contaminated soil.