ABSTRACT

The concentration of heavy metals in Imo-River was determined from source to tributaries using Atomic Absorption Spectroscopy (AAS), to ascertain the influence of urbanization and farming practices n this river. Physico-chemical parameters such as pH, total water hardness, BOD5, DO, COD, chloride, bicarbonate, nitrate, sodium, potassium, calcium and magnesium were also determined. Sodium and potassium were determined using Flame Emission Spectroscopy (1ThS). Of all the pollution indices studied, the most outstanding are the pH, DO, BOD5, COD and the levels of Lead, Iron and Mercury observed. The river is acidic all season (pH range from 5.15 — 6.95). The acidity is however tolerable to aquatic life. The dissolved oxygen level is most often dangerously low (2.51 — 5.16 mg/dm3) and BOD5of 2.5 — 7.45 mgldm3. These parameters have put a strain to aquatic life. The total hardness of 9.10 — 40.91 mgldm3) permits the use of the water as a domestic water source especially for laundry when treated. Cadmium and cobalt occurred in trace amounts and so were not detected. Mercury was detected but the levels were very low. The river was heavily leaded, especially in the dry season (0.05 — 0.4 mgldm3) as analysis showed an annual mean lead level of 0.4omg/dm3. The levels of iron (15.00-24.30 mg/dm3) and zinc (0.15 — 0.25 mg/dm3) although high enough to cause some concern were within the limits prescribed by WHO. In contrast to lead, mercury and zinc, iron showed more concentration during the rainy season. There were significant differences between values recorded for each heavy metal for the two seasons using analysis of variance (P < 0.05). The significance of the entire result to public health practitioners and the Federal Environmental Protection Agency (FEPA) is now obvious since the people who live along the river are now aware that proper treatment of such water is a matter of necessity.