Variations in Water Quality Index and Physicochemical Properties of Surface Water and Bottom Sediments of Selected Coastal Beaches of Niger Delta, Southern Nigeria

This study aimed to determine variations in water quality index (WQI) and physicochemical properties of surface water and bottom sediments of selected coastal beaches of Niger Delta, Southern Nigeria. The water quality of the river is categorized into five classes, which are classes I, II, III, IV and V based on the WQI (derived from the determination of DO, BOD, COD, TSS and ammonia and pH). Water and bottom sediment samples were analysed using standard procedures. During the wet season, physicochemical parameters such as potential hydrogen (pH), electrical conductivity (EC), dissolved oxygen (DO), total dissolved solids (TDS) and salinity showed significant difference (p < 0.05) across all the locations. During the dry season, parameters like EC, EA, pH, sodium (Na), sulphate (SO4), chloride (Cl-), potassium (K), effective cation exchange capacity (ECEC) and calcium (Ca) showed significant difference (p < 0.05) across all the six sampled beaches while phosphate (PO4) did not show any clear significant difference across all the sampled locations. The general trend in the levels of physicochemical parameters revealed that temperature and pH were within those recommended by World Health Organization (WHO) and United States Environmental Protection Agency (USEPA) for both wet and dry season but EC and TDS were above the WHO and USEPA limit. Twenty one (21) water quality parameters from six sampling locations were studied and by applying WQI, the state of the six beach water was very unsuitable for drinking, swimming and recreational activities as at the time of this study. The water is only suitable for irrigation purpose.