Application of Festuca arundinacea in phytoremediation of soils contaminated with Pb, Ni, Cd and petroleum hydrocarbons

Abstract

Phytoremediation is a promising "green technique" used to purify contaminated soils. The performed phytoremediation experiments assisted by the fertilization process involving pots of F.arundinacea grown on soils with diverse concentrations and types of contaminations produced the following decreased percentages after 6 months: Pb (25.4-34.1%), Ni (18.7-23.8%), Cd (26.3-46.7%), TPH (49.4-60.1%). Primarily, TPH biodegradation was occurring as a result of basic bioremediation stimulated by adding optimal volumes of biogenic substances and corrections in the soil reaction, while phytoremediation improved this process by 17.4 - 23.1%. The highest drop in a range of 45.6 - 55.5% was recorded for the group of C₁₂-C₁₈ hydrocarbons, with the lowest one for C₂₅-C₃₆, amounting to 9.1-17.4%. Translocation factor values were: TF<1 and ranged, respectively, for: Pb (0.46-0.53), Ni (0.29-0.33), and Cd (0.21-0.25), which indicate that heavy metals absorbed by Festuca arundinacea they mainly accumulated in the root of the tissue in descending order: Cd <Ni <Pb, showing poor metal translocation from roots to shoots. Co-occurrence of petroleum pollutants (TPH) in contaminated (Pb, Cd, Ni) soils results in reducing their contents in Festuca arundinacea roots. The process of phytoremediation of contaminated soil using F.arundinacea assisted with fertilization was monitored by means of toxicological tests: Microtox SPT (inhibition of the luminescence of V. fischeri), Ostracodtoxkit F (mortality, growth inhibition Heterocypris incongruens) and MARA (growth of 11 microorganisms) and Phytotoxkit F (germination assessment, inhibition root growth: Sorghum saccharatum, Lepidium sativum and Sinapis alba). The sensitivity of toxicological tests used was comparable and increased in the order: MARA<Ostracodtoxkit<Microtox. The performed phytotoxicity tests have indicated variable sensitivity of the tested plants on contaminants occurring in the studied soils, following the sequence: L. Sativum<S. saccharatum<S. alba. The obtained results indicate a decrease in soil toxicity during phytoremediation assisted by the fertilization process using Festuca arundinacea, which correlates with a decrease in the amount of harmful impurities contained in soils subjected to phytoremediation.

Keywords: Festuca arundinacea; Heavy metals; Phytoremediation; Soil; Total petroleum hydrocarbons; Toxicological test.