Biochemical changes in L. terrestris, physicochemical parameters and heavy metal contents in soil and phytoremediation quotient of Talinum triangulare were investigated. Soil samples, T. triangulare roots and stems and earthworms were obtained in two oil exploration environs (A and B) of Ugberikoko and Oton Village (control; site C) in Delta State and were subjected to chemical and biological analyses. Results obtained showed that cadmium, lead, copper, manganese, zinc, iron and nickel levels in soil were significantly (p < 0.05) higher in sites A and B compared to site C whereas arsenic and cobalt were below detection limit. The pH, nitrate, sulphate, phosphate, hardness and magnesium contents were significantly (p < 0.05) higher in sites A and B compared to site C. The heavy metal content in roots and shoots of T. triangulare were significantly (p < 0.05) higher in sites A and B compared to site C. The order of mobility and bioavailability of the metals analysed shows that Mn > Cu > Fe > Zn > Cr. Oxidative stress indicators such as MDA, GST, CAT and SOD were significantly (p < 0.05) elevated in the supernatant of earthworms from sites A and B when compared with site C whereas GSH level was significantly (p < 0.05) lowered in sites A and B compared to site C. The activity of acetylcholinesterase was significantly lowered (p < 0.05) in sites A and B compared to C. This result suggests that earthworm may be a good candidate for the assessment of soil pollution and that T. triangulare could be used for commercial and environmental friendly phytoremediation.
Key words: Lumbricus terrestris, Talinum triangulare, heavy metals, physicochemical parameters, phytoremediation, petroleum flow station.
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