Statistical analysis of atmospheric pollutant concentrations in parts of Imo State, Southeastern Nigeria

Abstract

This study was carried out to analyze the concentrations of some atmospheric pollutants in some parts of Imo State, southeastern Nigeria using statistical techniques. In the present study, PM10, NO2, SO2, CO, VOC and H2S in some parts of Imo State Southeastern Nigeria were analyzed to determine their presence, concentrations and possible sources of emission. This study also tried to establish possible relationship between pollutants spatial variation and dispersion with industrial and anthropogenic activities within the study area. The study area includes Egbema, Orlu, Okigwe and Orlu areas of Imo State, Nigeria. Air quality data was collected three times a day (morning, afternoon and evening) using the Gasman Air Monitors which was specifically used for SO2, NO2 and CO measurements, the Haze-dust Particulate Monitor 10 µm was used for PM10 data acquisition. Similarly, the Aeroqual Gas Monitor Model 300 was used for H2S measurement while the Ibrid MX6 Gas Monitor was used for VOC measurement. Results of the study revealed that the mean PM10 and CO levels in the locations exceeded the 24 h limit of 150 µg/m3 and 35 ppm of the United States National Ambient Air Quality Standards (US NAAQS) respectively. In addition, the mean concentrations of NO2 was above the annual limit of 0.053 ppm as prescribed by US NAAAQS, while the mean values of SO2 were within the annual and 1–hour limits of 0.5 ppm and 0.075 ppm respectively as stipulated by the US NAAQS. Whereas significant concentrations of H2S were not detected in the various locations, elevated concentration of VOC were recorded within Egbema area indicating possible influence from gas flaring and other crude oil related activities. The ANOVA and Box and Whisker plots revealed remarkable variations of the air pollutant concentrations in the study area. In addition, while the Hierarchical Cluster Analysis (HCA) grouped the pollutants into one major group, Principal Component Analysis (PCA) further grouped them into one coherent component indicating similar source of emission. The findings of this study therefore showed the need for regular air quality monitoring of the area to forestall adverse environmental problems. Keywords: Statistical analyses, Atmospheric pollution, Wind rose, Particulate matter, Imo State