EFFECT OF SEASONAL VARIATION ON THE PHYSICO-CHEMICAL PROPERTIES OF SURFACE WATER AND SEDIMENTS OF SOMBRIERO RIVER IN RIVERS STATE, NIGERIA

Due to the vulnerability of the Sombriero River to contaminants, the effect of seasonal variation on the physico-chemical characteristics of the Sombriero River was investigated with respect to its sediment and surface water samples to ascertain the degree of alterations from the natural background level of the river and adherence to regulatory standards. Surface water and sediments were collected at seven selected sites along the Sombriero River. The dry season sampling was carried out in December, 2020, while the wet season sampling took place in May, 2021. The samples were analyzed in the laboratory following standard operational procedures. The results indicated high alterations (p< 0.05) in the concentrations of cadmium, nickel, zinc, iron, total dissolved solids, turbidity, biochemical oxygen demand, and chemical oxygen demand, beyond the background values of Nigeria’s Department of Petroleum Resources (DPR) and Federal Ministry of Environment (FMENV). The majority of the heavy metals, notably copper, cadmium, lead, manganese, nickel, zinc, and iron, had higher concentrations in water during the dry season, while sodium, potassium, and magnesium showed an increase in concentration in surface water during the wet season. However, the pH level was within the target background values of DPR and FMENV, and showed no significant variation in the dry and wet seasons. For instance, surface water had a pH range of 6.65 –7.18 in the wet season, and 6.93 –7.18 in the dry season. Sediments ranged from 6.06 – 6.59 and 6.10 – 6.88 during the wet season and dry season, respectively. The quality of water influences the health status of any populace, hence, analysis of water for physical, chemical, and biological properties is very important.