Effects of coal ash containing elevated uranium decay chain radionuclides on native Octodrilus lissaensis in landfills, focusing on element transfer, radiation dosage, and toxicity assessment.

In this study, the effects of long-term exposure of native earthworms (Octodrilus lissaensis Michaelsen, 1891) that inhabit the disposal site of coal ash with enhanced content of uranium decay chain radionuclides were investigated. The concentrations of V, Fe, Ni, As, Se, Rb, Mo, Sn, Sb, Th and Hg were significantly higher in earthworms from the disposal site, while those of Na, K, Ca, Mn and Co were lower compared to the control. The activity concentrations of 238U, 226Ra, 210Pb and 210Po were six to nine times higher than those in the control group. The mean dose rate of ionizing radiation to the earthworms in the disposal site was 18.3 μGy h-1, slightly exceeding the threshold value of 10 μGy h-1. No significant difference was observed between the earthworm groups for soluble proteins. However, lipid peroxidation in earthworms from coal ash site increased as evidenced by 30 % higher malondialdehyde levels than in control. Additionally, a significant induction of glutathione S-transferase activity and inhibition of catalase was detected in the coal ash group compared to the control group. Considering the long-term presence of O. lissaensis on the coal ash disposal site, these earthworms seem to have adapted to such conditions, despite the increased bioaccumulation of contaminants and consequent changes in toxicity and oxidative stress parameters.