Polycyclic Aromatic Hydrocarbon in Vegetables Grown on Contaminated Soils in a Sub-Saharan Tropical Environment – Lagos, Nigeria

Abstract

Diet has been established as a major source of exposure to Polycyclic aromatic hydrocarbon for humans (PAHs) especially nonsmokers. Therefore their presence in plants constitute a major health concern. This research aims at determining the concentration and profile of sixteen US-EPA priority PAHs in tropical edible vegetables (Corchorus olitorius (Ewedu), Celosia argentea (Soko), Amaranthus cruentus L (Grain amaranthus/Tete), Telfairia occidentale (Ugwu), Basella alba (Amunu tutu/White Spinash), Lactuca Sativa (Lettuce), Allium ascalonicum (Spring Onions/Alubasa elewe), Talinum Triangulare (Water leaf)), grown on potted contaminated soils. Vegetable grown on potted contaminated soils and contaminated soils were extracted using n-hexane/acetone mixture in ultrasonic bath. Extracts were purified using C18 solid-phase extraction cartridge (5 mL). Resultant extracts were quantified for PAHs on an Agilent 6890 Gas chromatography/mass spectrometer (GC/MS). Total PAH concentration in contaminated soils and plants grown on them were 200 - 250,000 ng g−1 and 100-5,000 ng g−1, respectively. Two and three ringed PAHs which are the less toxic were the dominant PAH type present in most of the plant parts. Telfairia occidentale (Ugwu) consistently grew on all the soils samples which suggest it possess some potential for phyto remediation. Lactuca sativa (Lettuce) had few growth only the least contaminated soils. Its ability to grow on soils with low contamination makes it a potential bio indicators for polluted soils.