Behavioural dynamics of water quality parameters and human exposure assessment of trace metals in Agulu Lake Water, South-East Nigeria

Lakes in South-East Nigeria are vital for domestic and agricultural water use, yet increasing anthropogenic pressures raise concerns about trace metal contaminations and associated health risks. A total of 100 water samples were collected from ten stations of Agulu Lake during dry and rainy seasons. Fifteen water quality parameters, including trace metals, were analyzed. Multivariate indices; heavy metal pollution index (HPI), toxicity load, and hazard index (HI); were applied to evaluate contamination levels and potential human health risks. The dominant trace metals were Cr (range: 0.11–1.20 mg/L) and Pb (range: 0.33–1.08 mg/L) during the dry season, whereas in the rainy season Cr (range: 0.51–1.43 mg/L) and Pb (range: 0.29–0.51 mg/L) remained the most prevalent. NO₃^- and NO₂^- peaked at the IEN and OYT stations in the dry season. HPI indicated Cd and Pb as the major contributors to water quality deterioration. Toxicity loads of Cr, Mn, and Cu reached 589,536.5, 141,405.6, and 196,262.4 in the dry season, with notable seasonal shifts. The HI values for all sampling locations were greater than 1, designating the lake as a high-risk zone. Agulu Lake water is unsafe for human consumption due to trace metal contamination, primarily from Cd, Cr, and Pb. Identification and control of point sources of pollution are urgently required to protect public health.