بررسي اثر گياه پالايي بر كاهش هيدروكربن هاي نفتي (TPH) در يك خاك آهكي

An Investigation of the Effect Phytoremediation on Dissipation Rate of Total Petroleum Hydrocarbons in a Lime Soil

Phytoremediation is a remediation technique that either involves plant uptake, transformation, accumulation, and / or volatilization of soil and aqueous-phase contaminant or acts by stimulation of microbial activity in the rhizosphere of the plant. In this study the effect of planting tall fescue (Festuca arundinaceu), alfalfa (Medicago sativa) on dissipation rate of total petroleum hydrocarbons (TPH) from soil contaminated with different levels of light crude oil was investigated. Tall fescue, alfalfa and a mixture of the two were planted in 800g pots of either uncontaminated and contaminated (1, 3, 5, 7 and 10 percent crude oil) soil, and kept to be grown in lab for 4 months. Soil samples from the phytoremediation experiments were collected at 0, 30, 60 and 120 days after the start of experiment and sorted at 4°C before being tested for the dissipation rate of TPH. The dissipation rate of TPH was significantly different in planted as compared with unplanted soil in all percentages of crude oil content. The highest decrease in TPH concentration occurred during the first month of growth. Dissipation rate of TPH decreased with enhanced oil concentration. The most dissipation was observed in soil with one percent of crude oil and thatwhich was planted with a mixture of tall fescue and alfalfa (75.5%). The lowest dissipation (18.8%) occurred in unplanted soil contaminated with a ten percent of crude oil. In this study it was demonstrated that the dissipation rate of TPH was faster in planted soil than in unplanted soil, despite the fact that the difference between dissipation rates in planted and unplanted soil decreased with enhanced crude oil concentration. It is postulated that decreased dissipation rate in high crude oil concentrations is a result of decreased plant biomass.