Water quality and environmental health indicators in the Andoni River estuary, Eastern Niger Delta of Nigeria

Abstract

Indicators of water quality in open coasts, estuaries, and inlets including nutrients, water clarity, and toxicants were investigated in the Andoni River estuary in the eastern Niger Delta of Nigeria using standard methods. DO was generally below 5 mg/L and 20 % of sampled sites had turbidity levels above standards recommended for estuarine ecosystems. The sampled sites also did not meet international standards for nitrate, heavy metals, and hydrocarbons, exceeding limits for natural resource preservation, coral reef conservation, and aquaculture by very wide margins. Nitrate ranges were between 0.6 and 1.5 mg/L; THC (4.6–52.6 mg/L) heavy metals (Fe 0.45–1.54 mg/L, Mn 0.004–0.19 mg/L, Ni 0.08–0.16 mg/L, Cd 0.02–0.5 mg/L, Pb 0.14–0.44 mg/L, and Zn 0.06–0.17 mg/L). A Water Quality Index calculated for the whole river system showed a declining capacity to support fish and aquatic grass habitats. This study, therefore, concludes that the estuary is suffering pollution from immediate hydrocarbon pollution sources and local pollution from eroded contaminated sediments, discharged domestic and human waste, and long distance river pollution. A comprehensive scientific investigation of estuarine conditions, source control measures for known pollutants, and source conversion of fecal sludge in riverine communities are among recommendations.