Rainfall water quality assessment in atmospheric deposition of an urban area: A case study of Akure in Nigeria

The physicochemical properties of rainfall and dry deposition of Akure, Nigeria were measured over a period of one year (July 2015 to June 2016) at six different locations. A total of 72 rainwater samples was analyzed for the Total Dissolved Solid (TDS), Temperature, pH, Electrical Conductivity (EC), Free CO2, and Acidity using standard methods. The mean results depicted - TDS (22.51mg/L), Temperature (28.2oC), pH (6.92), EC (44.75 µS/cm), Free CO2 (20.97 mg/L), and Acidity (254.83 mg/L). Only three of the rain water samples were observed in the acidic range ( 4.6) suggesting that the presence of alkaline particles in the samples were not high enough to neutralize acidic species available in the water. Multivariate statistical analyses, such as Factor Analysis as well as Correlation Matrix showed significant anthropogenic pollutant intrusions in the rainwater samples. Cluster Analysis revealed the similarity between TDS and EC and this was confirmed by Pearson Correlation Coefficient (r = 0.99) at a significance level of 0.05. The study suggested that traffic activities were the main sources of deposition in the locations under this study.