Impact of Waste Dump on Heavy Metal Pollution of Riverbank Soil and Physico-chemical Properties of River Arumangye in Doma, Nasarawa State, Nigeria

Abstract

In Nigeria, rivers and streams are natural water bodies that flow through cities and town. These rivers and streams are badly kept with their banks serving as disposal site. A study was conducted in 2015 in river Arumangye, with the aim of evaluating the effect of waste dump on heavy metal pollution index of the riverbank soil and assessed the quality of water. The result revealed that the riverbank soil was contaminated with heavy metals. The largest concentration of heavy metal present was Nickel (54 mg/kg) followed by Iron (5.04 mg/kg), Manganese (1.66 mg/kg), Cadmium (1.15 mg/kg),  Cupper (0.65 mg/kg), Zinc (0.64 mg/kg) and the least was Lead (0.16 mg/kg). These metal content increases in ascending order in the soil as follows: Pb < Zn< Cu < Cd< Mn < Fe < Ni. However, the riverbank soil pollution index showed a reverse trend as follows: Mn < Ni< Zn < Cd< Pb < Cu < Fe. The pH Value of water from downstream was 6.45 which is slightly acidic than the upstream pH value of 8.12, while the midstream was 7.02. The WHO standard for a good drinking water has a pH value of 7.0-8.5. Also, ammonia nitrogen concentration on the downstream is high with a value of 0.64 mg/l, which is higher than the upstream (0.40 mg/l) and the midstream value of 0.49 mg/l; which is lower than the WHO standard value of 0.5 mg/l ammonia. Concentration of chloride at upstream was 23.00 mg/l, midstream sampling point had 24.00 mg/l of chloride compound and the downstream recorded the highest concentration of 28.80 mg/l of chloride. Dissolved oxygen in upstream was 3.80 mg/l of oxygen, midstream had 2.10 mg/l of oxygen and the downstream had a concentration of 1.90 mg/l of dissolved oxygen. The carbon dioxide concentration was more on the midstream (27.62 mg/l) sampling point compare to the upstream (18.67 mg/l) and downstream (18.69 mg/l). The water hardness was more at the upstream        (22.00 mg/l), while at the midstream it became 20.00 mg/l and decreases again at the downstream to 18.78 mg/l. Therefore, dumping waste in river Arumangye contributed in polluting the river bank soil with heavy metals. However water quality of the is river still good for consumption; since most of the parameters assessed are within WHO minimum standard requirement of a good drinking water.