Spatio-Temporal Study of Criteria Pollutants in Nigerian City

Aims: An investigation of characteristic long term air pollutants known for temporal and spatial behaviors was conducted due to increased pollution scenarios in Nigerian cities as a result of deprived environmental enforcement of statutory obligations.

Study Design: One of the worlds’ most polluted cities (Onitsha lower basin) in Nigeria was selected for spatio-temporal study of three criteria pollutants combined with GIS and MATLAB alongside associated meteorological conditions during harmattan.

Methodology: 72-hourly analyses of the nine different locations having 4 sampling sites and 500 meters apart were done from December to February which generated over 19, 440 experimental data per quarter of each annual study.

Results: Upper Iweka/Nitel area recorded the highest concentration of SO2 pollutant at (94.2 µg/m3) due to longer residence times and low wind mixing height. Borromeo hospital showed the least active NO2 region but converges at points 1 due to North-east wind dissimilar to sampling points 1 having the lowest PM10 distribution. Measured temperature parameter correlates inversely with relative humidity and precipitation. The GIS spatial representation corresponded to temporal variability of gaseous and particulate pollutants.

Conclusion: All sampled areas had AQI above 50; hence the study identified SO2, NO2, and PM10 as Primary pollutants of Onitsha lower basin.