The potential of common duckweed (Lemna minor) in phytoremediation of phenanthrene and pyrene

The distribution of polycyclic aromatic hydrocarbons (PAHs) as a group of toxic and persistent aromatic pollutants in the environment is rapidly enhancing. These compounds have adverse impacts on the health of living organisms. Hence, in the present study, we investigated the potential of duckweed (Lemna minor) as an aquatic plant species for uptake, accumulation, and biodegradation of phenanthrene and pyrene under controlled conditions. L. minor plants were treated with 10 and 20 mg L-1 concentrations of phenanthrene and pyrene at the experimental duration of ten days. According to the results obtained, the toxicity of phenanthrene and pyrene contaminants on L. minor was influenced by the different initial PAHs concentrations. An increase in phenanthrene and pyrene concentration significantly decreased all studied growth parameters such as fresh weight, dry weight, and RFN and also photosynthetic pigment contents of the plant. Phenanthrene and pyrene concentrations were measured using high-performance liquid chromatography (HPLC) technique after 10 days of exposure to the PAHs. The results revealed that L. minor species could bioaccumulate effectively both typical PAHs. Furthermore, the gas chromatography-mass spectroscopy (GC/MS) technique explained the biological degradation of phenanthrene and pyrene by L. minor in the present research, and accordingly, several intermediate by-products were identified.