Comparative Bio-accumulation Potential of Chromium and Cadmium and Their Toxic Effects on Morphology of Earthworm’s Species, Pheretima posthuma

Abstract

İn this study research was conducted to investigate the accumulative ability and devastating effect of Chromium sulfate (CrSO₄) and Cadmium chloride (CdCl₂) on the growth of earthworm (EW), Pheretima posthuma. An experimental trial conducted in the Labortory of the Department of Zoology, Wildlife and Fisheries, University of Agriculture Faisalabad. After acclimatization, earthworms reared in jars were divided into five groups with three replicates, Group A controlled, Group B was given 200mg/kg CrSO₄, Group C was given 300 mg/kg CrSO₄, Group D was given 200mg/kg CdCl₂, Group E was given for 300mg/kg CdCl₂ treated-soil, respectively. The flame spectrophotometer was used for the quantification of absorption of heavy metals. After 30 days post-exposure, the highest Cr accumulation (8.88±0.07 mg/kg ) was detected in group C while highest accumulation of Cd (7.81±0.09 mg/ kg) was detected in group E. Furthermore, it was noted that these significant accumulations resulted in weight and length reduction. The highest weight reduction (-1.23±0.02g) was observed in group C while the lowest weight reduction (-1.15±0.01g) was observed in group E. Similarly, the highest length reduction (-1.82±0.03cm) was observed in group C while lower length reduction (-1.745±0.24cm) was noted in group E. It was evident that Cr has a more deleterious effect on earthworm growth than Cd. The control showed weight gain (0.26±0.05g) and length gain (1.98±0.27cm). The result of the study were statistically significant (P<0.05). Taken together, it was concluded that earthworm has great potential for bio-accumulation of available heavy metals (Cd and Cr) in the soil and Cr has a higher potential for bio-accumulation than Cd. Although earthworm has a great tendency to survive in a heavy metal environment, their body mass is reduced due to heavy metal toxicity. This study aims to understand the storage of heavy metals in earthworms and to investigate their bioaccumulation ability. This study aims to how heavy metals are stored in earthworms and investigate their capacity for bioaccumulation.