Impact of Anthropogenic Activities on Eutrophication of Anambra River in Anambra State, Nigeria

Abstract

Eutrophication of Anambra River in Anambra East Local Government Area of Anambra State, Nigeria was carried out. Water samples were collected from five different sampling points in the river designated as A, B, C, D and E. Sample point A was upstream, Sample point B was downstream, while Sample points C, D and E were points of waste discharge. The water quality parameters assessed were colour, turbidity, conductivity, total dissolved solids, total suspended solids, total solids, potassium, dissolved oxygen, iron, phosphate and nitrate. The result of analysis revealed the degree of eutrophication of the river. There were variations in the level of the parameters measured across the sampling points. The parameters varied between 1.04 – 3.26 units, 1.21 – 4.64NTU, 12.31 – 32.48 mg/l, 1.27 – 8.10 mg/l ,1.43 – 3.86 mg/l, 2.70 -11.96 mg/l, 3.00 -16.84 mg/l, 1.00 – 3.01 mg/l, 1.21 – 3.74 mg/l, 0.02 – 0.30 mg/l, and 0.02– 0.08 mg/l. for colour, conductivity, total dissolved solids, total suspended solids, total solids, potassium, dissolved oxygen, iron, phosphate, nitrate, faecal coliform and total coliform respectively. All the parameters met the WHO standard for drinking water. However, nitrate and phosphate values exceeded the critical concentrations of 0.3 mg/l and 0.01 mg/l respectively, said to trigger eutrophication if exceeded. The result further revealed that sampling point E (Point of Waste discharge) recorded the highest concentrations of the parameters while sampling point A (Upstream) recorded the least. Statistical analysis revealed significant correlation between some of the parameters. Since detergents constitute a major source of phosphate in rivers, legislation against the use of phosphate in detergents was recommended.