ABSTRACT
Water plays a vital role in the physical and biological activities of humans and animals. The lentic systems like the natural ponds, are progressively been threatened by the activities of humans because of the great demand for the physical and biological assets it possesses for human consumption. This study evaluated the water and sediment characterization in relation to the macro benthic invertebrates in selected natural ponds at Oghara, Delta State.
Samples of the surface water were collected using sampling bottles while samples of the sediment were collected using an Ekman-grab. The samples were analyzed for physicochemical parameters using standard methods. Macrobenthic invertebrates’ diversity was calculated using Shannon Weiner's index. Human health risk was assessed using human intake models to evaluate the risk of exposure to heavy metals through drinking of contaminated water.
Results showed that water physicochemical parameters were not significantly different (p> 0.05) across the stations except for electrical conductivity, potassium, sodium, total hardness, and chromium. For the sediment, physicochemical parameters were not significantly different (p>0.05) across the stations except iron, manganese, organic carbon, and organic matter. Selected ponds were slightly polluted with the influx of organic materials like sewage and suspended particles. Human health risk assessment of the water indicate non – carcinogenic health risk to consumers (HI < 1), and carcinogenic risk to consumers. Ecological risk indices of contamination factor, pollution load indexand I-geo were < 1. Potential Ecological Risk Index (PERI) values ranged from 9.86 to 31.22, with Station 2 having degree of contamination index > 1, an indication that station 2 was more polluted compared to other stations. For macroinvertebrates, 182 individuals from 16 different taxa with composition of Hemiptera (6%), Coleoptera(15%), Odonata(10%), Diptera(53%), Ephemeroptera (7%), and Mollusca (3%). Shannon Weiner's index indicated that Station 3 had the most diversity. Distribution and abundance of benthic macroinvertebrates were shown to be influenced by changes water and sediment physicochemical factors. The need for environmental regulation and the continuous quality monitoring of water sources to protect public health.
