Concentration and Distribution of Inorganic Ions in Rainwater of Jos and Bukuru Metropolis, Plateau State, Nigeria

Abstract

Rainwater samples were collected during the raining season from five sites within Jos and Bukuru metropolis from April to October, 2002 and 2007. Eighty-five percent of the total rain events for the two years under study were sampled. The samples were analyzed using standard methods and results of the pH were attributed to increase in vehicle traffic within the study area. The concentration of the components Cl-, NO3-, NO2-, SO4-, PO43-, NH4+, Na+, K+, Ca2+, Mg2+ and Cu2+ were determined along with some other physical parameters. Colorimetric method was used to determine the concentration of the nonmetallic radicals while Atomic Absorption Spectrophotometry (AAS) was used to determine the concentration of the metals. Data obtained showed significant correlation of SO42- with Cl-, NO3-, NO2-, SO42-, PO43-, NH4+, Na+, Mg2+ and Cu2+. Also NH4+ correlated significantly with Cl-, Na+, K+, and Ca2+. These indicate the predominant anthropogenic sources, existence of aerosols such as (NH4)2SO4, NH4Cl, NH4NO3 and some other photochemical processes that occur below the cloud level. Data evaluated also reveal that local urban and industrial emission sources were primarily responsible for rainwater and atmospheric contamination which results in high ammonium and acidic pH concentrations. In this work, it was also revealed that increasing precipitation (rainfall amount) decreases the rainfall composition due to dilution and the deposition of rainfall composition is enhanced by high altitude of sites, with higher precipitation of ionic species between 15mm and 35mm of rainfall amount. The acidic nature of the rainwater indicates Jos and Bukuru metropolis rainwater to be hazardous for human consumption and may have adverse effect on human, plant, animal and material comfort.