Bioaccumulation of Pb (Lead) in the Muscles of Danio rerio and its Effect on the Anti-oxidant Enzyme Catalase in the Mining Vicinity of Kolar Gold Fields

Abstract

Background: The study has a bifold objectives, firstly to determine the concentration of lead (Pb) in the pond water and bioaccumulation of the lead in the muscles of Danio rerio raised with the same pond water. Secondly, the study seeks to investigate its effect on the anti-oxidant enzyme catalase in Danio rerio, within the vicinity of a historical gold mine region located in the Kolar Gold fields (KGF), Karnataka, India. Methods: To achieve the objectives, the study employed Thermo Scientific’s Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and ICP-AES using Iteva software to evaluate and statistically analyze the distribution of lead in the pond water and and ICP-OES to evaluate the concentration of lead in the muscles sample. Four sample sites (A, B, C and D) were selected based on their proximity to residential area. Pond water samples were analyzed between April and October 2022 following a southwest monsoon rain. Result: During the study in the pond water, sample site B and D exhibited an exceedingly high Pb concentration during October with 0.98 mg/L against 0.21 and 0.16 mg/L in April 2022 against the maximum permissible value of 0.05 mg/L by WHO 2008 and USEPA 2009, followed by site A and C. The control sample had a normal range of 0.01 mg/L. The concentration of Pb in the muscles on day 30 of October was exceedingly high in the sample site D with 1.9 mg/Kg against 1 mg/Kg on day 30 of April followed by the sample sites B,C and A, which is far above the threshold value as per the regulatory bodies (WHO 2008). The increase in the concentration of the lead decreases the catalase enzyme in the brain region of Danio rerio, the value goes down drastically from 112.3 (µM H2O2 utilized/min/mg protein) to 105.8 in sample site D between day 30 of April and October months, to that of the control value being stable from 151.7 to 150.94 (µM H2O2 utilized/min/mg protein). The outcome of this experiment will facilitate the assessment of pond water contamination levels and the likelihood of contaminants entering the aquatic environment, resulting in the bioaccumulation of heavy metals in the aquatic organisms. The above results clearly indicates the effect of south-west monsoon rain in increasing the levels of lead concentration in the pond water during the month of October to that of April, which indirectly affects the physiology and metabolism of the fishes raised in the contaminated habitat of Kolar Gold Fields.