Acidic precipitation and infrastructural deterioration in oil producing communities of Akwa Ibom State: a case study of Eket, South Eastern Nigeria

Abstract

To examine the impact of rain on iron roofing in Eket, the quality of direct and roof rainwater collected over a period of two weeks in May, 1999 were compared. Simultaneous study at Uyo, Akwa Ibom State Capital, served as the control. Rainwater parameters considered include: pH, conductivity, total dissolved solids, particulate matter, total hardness, chloride, sulfate, nitrate, iron, and ammonium. Measurements of wind direction and strength were also obtained for every rain event. During the study, an acidic rain of pH 5.4 was measured in a sample from Eket. A comparison of this direct rainfall with the corresponding roof rainfall showed a marked drop in chloride content from 1,050 mg/l in the direct rainwater to 28.4 mg/l in the roof rainwater. This drop is attributed to the reaction between HCl in rain and zinc in roofing material. A similar trend was also found in sulfate concentration, which was attributed to the reaction between H2SO4 in rainwater and the protective ZNO layer of zinc plated iron roofs. These reactions are responsible for the accelerated rusting of roofing materials in oil producing communities of Southern Nigeria. The main source of these acids in rainwater at Eket, is the Mobil Producing gas flaring operations at nearby onshore and offshore locations. During the wet season, flare gases are carried inland throughout Eket and environs by South West Trade Winds leading to persistent acidic rain in these communities with attendant infrastructural damages.



Key Words: Acid rain, petroleum gas flaring, air pollution, iron roof corrosion

[Global Jnl Environ Sci Vol.2(1) 2003: 47-52]