Wet deposition chemistry and neutralization potential in oil producing region of southern Nigeria

The aim of this work is to evaluate the atmospheric rainwater chemistry and neutralization potential in oil producing areas of southern region of Nigeria. Rainwater samples were analysed for pH, EC, Cl−, SO42+, NO3−, Ca2+, and NH4+. Correlation, principal component analysis (PCA) and neutralization indicators as source apportionment methods were used to determine atmospheric acid precursors . Results show that the collected samples were severely acidified with pH value of 5.5 in oil producing communities and weak acid: pH 6.5 in non oil producing areas and varied with seasons. Fractional acidity (FA) constituted 98–99% of neutralizing ability, neutralization factor (NF) recorded Cl−, Ca2+ and NH4+ in values of 0.41, 0.43 and 0.003 with Ca2+ from sea salt, being the most neutralizing substance than NH4+from agricultural practice. The neutralizing and acidifying potentials (NP/AP) recorded a mean of 0.4, showing weak alkaline effect on atmospheric acid rain in oil producing communities. The positive correlation among ionic species implicates pH, SO42+and NO3 as causes of severe atmospheric acidity. Conclusions were made that enforcement of the existing environmental laws to checkmate the emission of acid precursors is crucial for the survival of man and entire ecosystem. •SO42−, NO−3, and pH are responsible for acidity of wet deposition.•Seasonal variation influences the pH of atmospheric rainwater.•Rainwater is portable for use during peak rain.•Ca2+ neutralizes acid efficiently than other alkaline component in rainwater.•Proper enforcement of Emission control policy is key to reducing acid rain effect.