The physico-chemical characteristics of Imo River Estuary in southeastern Nigeria

Abstract

The physicochemical characteristics of Imo River Estuary were studied from April to September, 2011 to assess the water quality. The estuary is located at the coastal part of Ikot Abasi Local Government Area of Akwa Ibom State in southeastern Nigeria. Sampling was done monthly at fishing grounds in the estuary designated upper, middle and lower course, respectively. Mean water temperature was 26.2°C; transparency, 58.66cm and salinity, 12.66‰. Total dissolved solids, total suspended solids, and total solids had means of 7.91mg/l, 11.91 and 19.82mg/l, respectively. Alkalinity was 91.20mg/l; total hardness, 108.38mg/l; nitrate, 7.04mg/l and phosphate, 1.78mg/l. The upper course recorded highest values for water temperature (28.2±0.5°C), transparency (64.58±8cm), TSS (12.7±0.5mg/l), TS (20.6±0.4mg/l) and phosphate in sediment (3.8±0.3mg/kg). The middle course recorded highest values of BOD (4.9±0.1mg/l), hardness (119.9±1.2mg/l), nitrate in water (7.3±0.2mg/l), nitrate in sediment (12.2±0.34mg/kg) and phosphate in water (1.5±0.2mg/l). Lower course had highest values only in dissolved oxygen (13.3±0.4mg/l), salinity (20±1‰), pH (6.3±1.2), alkalinity (133.6±1.3mg/l), DO (18.3±0.4 mg/l), TDS (8.4±0.3 mg/l) and EC (2.7±0.1μS/cm). The possible reasons for the observed values of the physicochemical characteristics are discussed.

Key Words: Physicochemical characteristics, water quality, Imo River Estuary.