Impact of Anthropogenic Pressures on the Physico-Chemical Characteristics and Quality of Surface Water from Amadi Creek, Port Harcourt, Rivers State, Nigeria: Implication to Water Quality and Ecological Health

The physico-chemical characteristics of surface water is a determinant factor for the overall health and functionality of aquatic ecosystems. This study aimed to assess the physico-chemical characteristics and water quality index of surface water from Amadi Creek, Port Harcourt, Rivers State, Nigeria. Monthly samples were collected from three stations (1. Marine base jetty, 2. Niger Delta Development Commission, NDDC water front and 3. Eastern bye-pass bridge) between June and August, 2023 using standard methods. Water quality was analysed using the Single factor index (SFI), Nemerow pollution index (NPI), water pollution index (WPI) and Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI). The results showed no significant monthly variation in most parameters measured except turbidity, THC and TOC, which recorded highest values (mean ± SD, ANOVA p<0.05) in August (turbidity: 48.33±23.71 NTU and THC: 5.42±3.00mg/L) and June (TOC: 0.65±0.05mg/L) respectively. Spatially, most physico-chemical characteristics were consistent across stations except for EC, ORP, salinity and TDS which were significantly decreased at the Eastern bye-pass bridge. Nutrients (phosphate, nitrate and sulphate) levels did not exhibit any spatial or temporal variations. Comparing average parameters values to permissible limits showed that DO, EC, pH, salinity, phosphate, nitrate was within the permissible limit while temperature, turbidity, BOD, THC and sulphate exceeded permissible limits set by Environmental Protection Authority (EPA) Victoria, European Union (EU) and National Environmental Standards and Regulations Enforcement Agency (NESREA). The SFI identified total hydrocarbon (9.47), Sulphate (6.54) and Total hydrocarbon (6.50) again as the dominant pollutant in Marine base jetty, NDDC water front and Eastern bye-pass bridge respectively. NPI and CCME-WQI classified water quality across stations as moderately polluted and marginally acceptable respectively, while WPI rated Marine based jetty as heavily polluted (WPI 7.33) and the other two stations as impure. In conclusion, while some physico-chemical parameters are within acceptable limits, elevated levels of temperature, turbidity, BOD, THC, and sulphate signify substantial anthropogenic pressure. Although, there were slight variations among the water quality indices (SFI, NPI, WPI, and CCME-WQI), all indices consistently identified Marine Base Jetty as the most polluted, primarily due to hydrocarbon and sulphate followed by Eastern bye-pass bridge then NNDC water front recording notable pollution. Immediate remediation is necessary to mitigate water quality degradation in Amadi Creek.