Biochemical transmutation in Lumbricus terrestris and phytoextraction of heavy metals from the swamp of Challawa industrial layout, Kano, Nigeria

Discharge of untreated industrial effluents has been associated with soil contamination. Biochemical alterations in Lumbricus terrestris and remediation capacity of Azadirachta indica tree from industrial effluent discharge locations in Challawa (A and B) and Kura village (control location C) were assessed. Levels of nitrate, phosphate, iron, chloride, and hardness at locations A and B were significantly (p < 0.05) higher than those at location C, but their sulfate concentrations were significantly (p < 0.05) weaker. pH and magnesium concentration at location A were significantly higher than those at locations B and C. Levels of Fe, Cu, Zn, Pb and Mn in soils at the discharge locations were significantly (p <0.05) higher than those of C. Azadirachta indica tree (AIT) had a translocation factor (TF) > 1 for Pb and Zn, while its biological concentration factor (BCF) was > 1 for Fe. Values of biological accumulation coefficient (BAC) for AIT and soil contamination factor (CF) were <1 for the metals. Bioindicators of oxidative stress (MDA, GST, CAT and SOD) in earthworm supernatants from the discharge locations were significantly higher (p < 0.05) compared to that at location C, while their GSH levels were significantly (p < 0.05) lower. Acetylcholinesterase (AChE) activity in earthworm supernatants from discharge locations was significantly lower (p < 0.05) in comparison with the control. Trends in results revealed that AIT may be useful for extraction and stabilization of heavy metals in polluted soils. Also, the biochemical alterations in L. terrestris may serve as sensitive bioindicators of soil contamination.