Document Type : Research Paper
1 2Associate Professor, Department of Environment, Faculty of Natural Resources and Environment, University of Birjand, Birjand, Iran
2 aDepartment of Environmental Engineering, Faculty of Natural Resources and Environment, University of Birjand, Birjand, Iran
Inevitably, less than 0.1% of pesticides used for pest control reach their target pests and the rest enter the environment and pollute water resources causing adverse effects on fish. This study aimed to investigate the acute toxicity and histopathological damage of paraquat at different pH, hardness and temperatures on Gambusia holbrooki. Acute toxicity of paraquat was performed for 96 h and the physicochemical parameters were adjusted viz. pH 5, 7 and 10, hardness 0, 200 and 400 mg/L and temperature 18, 25 and 30 °C. Then, the histopathological effects of paraquat on gill tissue and intestine of Gambosia holbrooki were then evaluated after 21 days. Acute toxicity of Paraquat herbicide on Gambusia fish at pH = 5, 7 and 10, equal to 13.80, 17.78 and 15.48 mg / l, hardness = 0, 200 and 400 mg / l, equal to 7.94, 19.49 and 36.30 mg / l and temperatures = 18, 25 and 30 ° C were 64.56, 51.28 and 25.70 mg / l, respectively. Histopathological lesions of paraquat toxin in the gills of Gambusia holbrooki at pH= 5 mg/l included hyperplasia, curvature, a fusion of lamellae and lamellar synechiae. Histopathological lesions of paraquat toxin in the intestine of Gambusia holbrooki demonstrated swelling and a higher number of goblet cells, necrosis and erosion. According to the present study results, it can be safely concluded that acute toxicity concentrations of paraquat herbicide can have adverse effects on gills and intestines of Gambusia holbrooki, the severity of which depends on the physicochemical properties of the aquatic environment.