ABSTRACT

The research aimed at assessment of chemical stressors of water quality, sediment and fish of Qua Iboe River Estuary. The estuary is one of the areas zoned for industrial development in and around its environs. As such anthropogenic activities and extensive use of shorelines and near shore areas by humans have significant ecological impacts. The experimental sites were selected randomly in such a way that four sampling stations were selected with high coastal activities within the estuary and a control station with low coastal activities along the river segment. Water samples were collected in each of the sampling stations and examined from January, 2021 to October, 2022. The range values seasonal mean and standard error of physic-chemical parameters were studied and reported in comparison with WHO permissible limit. Electrical conductivity and chloride showed significant difference (p=0.05) in both seasonal and spatial variations. While physico-chemical paraemeters like turbidity, TSS, Bicarbonate TA, BOD, COD-Nitrate, phosphate showed no significant difference (p=0.05) in spatial variation. Correlation and hierarchical cluster dendrogram showed that the relationships were significant with all these parameters except turbidity in dry seasons. Sediment portrayed seasonal variation between the dry and wet season and showed significant difference at (p=0.05) for cadmium, chromium, copper, iron, lead. Zinc showed no significant difference (p=0.005). Vanadium, arsenic and cobalt were below detectable limits. Ordination of physico-chemical parameters in water and heavy metals in sediments by principal component analysis with varimax rotation distinguished 3 components with the sizes. The first component accounted for 80.51% of the variations due to physico-chemical parameters in water and heavy metals in sediments while component 2 and 3 explained 11.87% and 6.13% respectively of the variations in the data in wet season while in dry season the first component accounted for 77.39% of the variation due to physico-chemical parameters in water and heavy metals in sediments while components 2 and 3 accounted for 15.09% and 5.60% respectively of the variations in the data. Higher levels of trace metals in the sample sites compared to the control sites confirms the fact that the control site has a lower pollution status compared to other locations. This observation clearly shows that coastal activities impacted seriously on environmental variables. All the metals investigated in both seasons were below the Department of Petroleum Resources (DPR) target/intervention limits for sediment quality guideline except iron which was above the DPR target limit.