Spatio-temporal variations and pollution status of heavy metals in Ahi River, Ohiya, Umuahia, Nigeria

The levels of heavy metals in the environment have seriously increased during the last few decades due to human activities. Aquatic environment is a major recipient of heavy metal pollution. Heavy metal content of Ahi River was studied between May and October 2023 in three stations, compared with national standards to determine the water’s suitability for drinking. The water samples were collected and analysed using standard methods. The eight evaluated heavy metals and concentrations were: Iron (0.93-2.83 mg/L), Zinc (0.61-0.90 mg/L), copper (0.1-0.9 mg/L), lead (0.05-0.34 mg/L), chromium (0.08-0.64 mg/L), cadmium (0.03-0.21 mg/L), nickel (0.02-0.14 mg/L) and manganese (0.38-1.1 mg/L). All the metals exceeded limits for drinking water (except zinc and copper). The lowest and highest values for most of the metals were recorded in May and September 2023, respectively. However, station 3 had relatively high values in all the metals. The heavy metal content was influenced by geology, rainfall and human activities. Single factor pollution index (SFPI) and comprehensive pollution index (CPI) showed the water was polluted and unsafe while pollution load sharing rate (PLSR) showed that lead and cadmium contributed most to the pollution. The concentrations of the metals influenced the values of the indices, therefore, waters of Ahi River is not suitable for drinking but can be used for other domestic purposes.