Accumulation of Heavy Metals by Earthworms Exposed to Soil Contaminated with Thermal Power Station Condensate and Used Transformer Oil in Delta State, Nigeria

Abstract

Changes in soil properties that reduce environmental services always result in a decline in soil quality. A variety of stressors, which may be physical, chemical, or biological and originate from both human and natural causes, could lead to these modifications. Using conventional laboratory methods, this study examined the physicochemical properties and heavy metal concentrations of soil samples from the condensate dump site and the electric transformer site in Delta State, Nigeria, as well as the earthworms introduced into the soil samples at varying degrees of contamination. The majority of the physicochemical parameters were higher in the condensate dump site soil than in the electrical transformer site soil, according to the findings. The heavy metals analysis in condensate, electrical transformer oil, soil samples from condensate dump site, and electrical transformer sites shows metal concentrations ranging from Cu 0.03-7.54ppm, Zn 0.12 - 4.33ppm, As 1.26 8 4.88ppm, Cd 0.01 -1.72ppm, Pb 2.10 - 4.22ppm, Hg 0.25 -2.19ppm, Fe 0.29 -2.34ppm, and Cr 0.12-1.8ppm. The earthworm accumulated metals from the soil in a contamination-percentage-dependent manner. Except for cadmium, which was above the DPR-established limit, the soil's heavy metals were all within the acceptable DPR limits. The study revealed that exposure to thermal power station condensate and used transformer oil resulted in heavy metal accumulation in earthworms, highlighting the environmental risks associated with soil contamination and the need for proper monitoring of industrial waste disposal practices.