Relative toxicity of Lead and Nickel on acid and alkaline phosphatase in epigeic earthworm Eisenia fetida (Savigny,1826)

Abstract

Among the soil fauna, earthworms are not only acting as bioindicator to determine soil pollution but also they provided with some specific enzymatic biomarker to decode the soil contamination. In the present heavy metal toxicity study, the LC50 of lead (Pb) and nickel (Ni) were determined in both artificial and natural ground soil by acute toxicity test (14 days) in Eisenia fetida. Low observed effective concentration (LOEC) of mixture of both metals (Pb and Ni) were also determined through repetitive experimental acute toxicity test. In the chronic toxicity test (28 days), the experimental set up had been arranged as control (C), T1(1506.25 mg Pb), T2 (3012.5mg Pb), T3 (193.75mg Ni), T4 (387.5mg Ni), T5 (753.125mg Pb and 96.875mg Ni) and T6(1506.25mg Pb and 193.75mg Ni) per Kg of dry soil. After end of chronic periods, specific activity of acid and alkaline phosphatase were determined in the earthworm tissue. The mean difference of recorded specific activity values of both enzymes were significant (P<0.05) and also showed a significant negative correlation (P<0.05) between the specific activity both enzymes.