The aim of the study was to evaluate biological effects of snail exposure to soil collected from a coal mining area in Zimbabwe. Land snails, Achatina Fulica, collected from a relatively pristine environment and reared under laboratory conditions (for 1 year) were exposed for 45 days to the soils collected from four different sites. Heavy metals were assayed in soils and sail tissues whilst stress enzyme activities were assayed in snail tissues. Levels of cadmium and zinc measured in the soils were found to be 0.92 ± 0.21 mg/kg and 193.50 ± 79.83 mg/kg respectively above the world health organization maximum permissible limits of 0.8 mg/kg and 50 mg/kg. Cadmium and zinc were found to be approximately 4 fold higher in snail tissues exposed to the soil compared to snail tissues exposed to reference soils. The activities of superoxide dismutase, catalase, glutathione peroxidase and DT diaphoresis were significantly increased in snails exposed to soils from the coal mining area compared to the control soil (p<0.05). The highest enzyme activities were recorded in snails exposed to soil close to coal processing plant (Site C) and close to coal fired power plant (Site D). Metallothionein concentrations were highest in snail tissue exposed to soil from site D. Our results show that invertebrates exposed to soil at the coal mining area are under oxidative stress. There is need, therefore, to continually assess contaminants in soils at coal mining areas.
Published Date: 2023-08-29; Received Date: 2023-01-31
