Abstract
Arable lands irrigated with wastewater in Bauchi and its environs were sampled and the soil, wastewater and the edible parts of the vegetable were analyzed for heavy metal content using atomic absorption spectrometry (AAS). Results obtained from the analysis revealed the presence of heavy metals in the nine studied areas which indicates that the vegetables acquired the metal ions from the system. The concentration of available heavy metals increased in this order, Buzaye > Kogin Hayin Gada > Kogin Bundili > Kogin Kamfani > Kofar Gombe > Bayara > Yelwa Tudun > Gubi > Bayar Rafin na Daya for both soil and wastewater analysis and were above WHO/FAO permissible threshold for edible foods. The concentration of extractable heavy metal in the system however was increased during the pot experiment by charging the wastewater with dilute salt solutions of heavy metal chloride. The plants subjected to pot experiments were watered periodically using the contaminated wastewater. Indigenous ectomycorrhizal fungi were introduced to the pot experiment to determine the efficiency as sequestering agent for the significantly increased heavy metal ions in the system. Obtained data reveals that the ectomycorrhizal fungi did diminish access of heavy metals into the edible part of the vegetables suggesting that ectomycorrhizal fungi formed complex chelate ligands and/or adsorbed the metal ions on the chitin within the fungal cell walls. The bioaccumulation efficiency was calculated and discussed.

Key words: Bioaccumulation efficiency Ectomycorrhizal fungi Heavy metals Wastewater Amaranth caudatus Hibiscus sabdariffa