Potentialities of six plant species on phytoremediation attempts of fuel oil-contaminated soils - PAHs impacts on bioconcentration and translocation factors

Abstract

To assess the phytoremediation potential of 6 plant species - Eleusine indica, Cynodon dactylon, Alternanthera sessilis, Commelinpa benghalensis, Cleome ciliata and Asystasia gangetica - on a soil contaminated with fuel oil (82.5 ml/kg of soil), experimentations have been conducted from March to August 2016. Only 3 plants (E. indica, C. dactylon and A. sessilis) survived and developed throughout the 150 days of experimentation. Only E. indica plants growing on polluted soils exhibited the best visual scores (3 to 4) throughout the study. C. dactylon stems in polluted soils were more reddish than those growing on unpolluted soils. Plants of A. sessilis growing on contaminated soils had a significantly greater stunting compared to its control (unpolluted). The relative growth indexes (RGI) of the growth parameters measured during the study shows similarities between plants of E. indica and C. dactylon on polluted and unpolluted soils; unlike A. sessilis, whose plants had significant growth delays compared to the control on contaminated soils. Soils physicochemical parameters do not present any difference between the beginning and the end of the experiments; excepted nitrogen levels which are significantly higher at the end than at the beginning of experimentation in all soils. TPHs concentration in soils have been reduced to more than 80% for E. indica and C. dactylon, to 77% for A. sessilis and 57% in non-planted soil. Bioconcentration and translocation factors values helped to understand the bioavailability and the soil-plant transfer of different classes of PAH established in this study according to their physicochemical properties. They also indicate that E. indica and A. sessilis promoted rhizodegradation and phytoextraction of hydrocarbon-polluted soils whereas C. dactylon was only implicated into rhizodegradation. However, E. indica and C. dactylon out-yielded A. sessilis in the phytoremediation capacity of fuel oil-contaminated soils.