Effect of heavy metals toxicity on mortality, bio-molecules and antioxidative enzymes of Eudrilus eugeniae
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Date
2020
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CCSHAU,HiSAR
Abstract
Earthworms are potentially the most important constituents of the soil biota in respect of soil formation and maintenance of structure and fertility of soil. Recent years have witnessed the contamination of soil ecosystem by heavy metals, which are considered to be one of the major environmental issues. Earthworms are terribly affected by soil pollution because of their strong interaction with soil. Heavy metals in increased concentrations have a variety of harmful effects on the viability, density, cocoon production, sexual development and growth of worms. The present study was carried out to investigate the effect of heavy metals on mortality, bio-molecules and antioxidative enzymes of E. eugeniae. The results showed the acute toxicity of two heavy metals individually as well as in combination of different concentrations on earthworms in a dose dependent manner which was evaluated in terms of mortality, growth (length and weight), cocoon production, bio-molecules and antioxidative enzymes. Maximum reduction in length (4.30 cm) and weight (0.42 g) of earthworm was seen in case of soil treated with Zn-0.1 ppm as compared to control. Maximum mortality of earthworms was 30% and number of cocoons reduced upto 29.67 in case of Zn-0.1 ppm contaminated soil. The maximum reduction in bio-molecules i.e. 19.63% in crude protein 28.57% in carbohydrate and 42.41% in crude lipid concentration was seen in earthworms treated with Zn-0.1 ppm. In case of antioxidative enzymes, there was an increase in the activities of antixidative enzymes due to oxidative stress induced by heavy metals. SOD (Superoxide dismutase) and POD (peroxidise) showed a maximum increase in activity at highest concentration of Zn (0.1 ppm) which was 10.26 U/mg protein and 0.77 U/mg protein respectively. Thus the study proves that zinc is more toxic and detrimental to earthworms as compared to cobalt.