Ecological risks Assessment of heavy metals from the Kidaro Creek, Niger Delta Nigeria

Abstract This study assessed the concentrations, distribution, and ecological risks of selected heavy metals (Pb, Cd, Ni, V, Cr, and As) in surface water and sediments of Kidaro Creek, Niger Delta, Nigeria during the dry and wet seasons. Surface water and sediment samples were collected from three stations and analyzed using standard analytical procedures. The concentrations of Pb, Cd, Ni, Cr, and V in surface water ranged from 0.355–1.761, 0.119–0.258, 0.320–0.505, 0.045–0.366, and 0.029–0.359 mg/L respectively in the dry season, and 0.284–1.669, 0.008–0.025, 0.214–0.381, 0.278–0.567, and 0.045–0.366 mg/L in the wet season, exceeding World Health Organization (WHO) limits for drinking water, while As ranged from 0.006–0.014 mg/L (dry season) and 0.040–0.181 mg/L (wet season). In sediments, Pb, Cd, Ni, Cr, V, and As ranged from 12.98–47.96, 0.41–3.82, 0.600–7.49, 2.259–12.060, 0.247–5.409, and 0.005–0.129 mg/kg in the dry season and 14.62–49.98, 0.013–0.380, 0.457–9.55, 1.362–13.937, < 0.001–0.007, and 0.492–1.220 mg/kg in the wet season. Ecological risk assessment showed extremely high contamination in surface water, with contamination factors ranging from 10.63–435.0 in the dry season and 1.10–228.67 in the wet season, while sediment CF values were generally low (0.011–2.146). Surface water pollution load index (PLI) ranged from 47.72–152.38 in the dry season and 2.89–25.69 in the wet season, whereas sediment PLI ranged from 0.073–0.137 (dry season) and 0.012–0.026 (wet season). The potential ecological risk index (PERI) for surface water ranged from 11105.67–22501.33 in the dry season and 1796.33–3293 in the wet season, indicating extremely high ecological risk, while sediment PERI values ranged from 25.62–145.85 (dry season) and 4.81–16.66 (wet season), indicating generally low ecological risk. Cadmium contributed the largest share of ecological risk (86% in dry season and 53.9% in wet season in surface water; >90% in sediments). The findings indicated that Kidaro Creek is significantly impacted by heavy metal pollution, largely driven by anthropogenic inputs associated with petroleum-related activities in the Niger Delta. Continuous environmental monitoring and effective pollution management strategies are necessary to safeguard the aquatic ecosystem and surrounding communities.