Temporal variation in water quality of selected earthen ponds of Effurun, Delta State, Nigeria

Abstract

This study assessed the temporal variations in water quality parameters in six earthen ponds in Effurun, Delta State, Nigeria, over six months, focusing on aquaculture suitability. pH remained stable (6.47–6.87) within NESREA standards (P > 0.05). Electrical conductivity (455.13 ± 207.11 µS/cm) and total dissolved solids (264.50 ± 102.20 mg/l) were below regulatory limits but increased significantly by June due to seasonal effects (P < 0.05). Turbidity (108.19 ± 44.09 NTU) and Total suspended solids (80.71 ± 44.40 mg/l) exceeded NESREA limits, peaking in April and February, likely due to sediment resuspension (P < 0.05). Potassium (0.67 ± 0.20 mg/l) and Alkalinity (20.42 ± 8.97 mg/l) showed moderate variations (P > 0.05), while Salinity (0.21 ± 0.08 g/L) and Sulfate (67.01 ± 13.84 mg/l) remained within acceptable limits (P > 0.05). Dissolved oxygen (6.14 ± 1.06 mg/l) met aquaculture requirements, and Biochemical oxygen demand (3.53 ± 1.07 mg/l) indicated low organic pollution (P > 0.05).Heavy metal concentrations exhibited no significant seasonal variations (P > 0.05). Iron ranged from 10.23 to 10.71 mg/l, Arsenic remained at 0.03 mg/l, and Cadmium varied slightly (0.32–0.33 mg/l). Nickel and vanadium were undetectable, while Barium (0.07 mg/l), Cobalt (0.02 mg/l), Chromium (0.11 mg/l), and Manganese (0.07 mg/l) showed minimal fluctuations. Zinc declined from 0.13 mg/l in January to 0.09 mg/l in March before stabilizing. Lead (0.03 mg/l) and Selenium (0.05–0.06 mg/l) remained stable.These findings highlight seasonal influences on some parameters but overall stability in heavy metal concentrations, underscoring the need for continuous monitoring to support sustainable aquaculture.