P.N Ede^1,, D.O. Edokpa²

Port Harcourt is a coastal city in Nigeria that has been experiencing large deposits of soot whose origin is not well known since the last quarter of 2016. Laboratory analysis however showed the soot to be a by-product of petroleum combustion. The HYSPLIT model developed by NOAA and Australia's Bureau of Meteorology was used to compute airborne particulate load, trajectory and dispersion over the city. Model outputs of ground level concentrations of particulates from area sources across receptors over the city for the hours of 0100, 0300 and 0700 when the soot incidence was most prevalent is here presented. Minimum and maximum emission concentrations dispersion across Port Harcourt ranged from 0.000035 mg/m³ to 0.18mg/m³ (0.035-180 µg/m³), respectively, for the hours considered. The maximum value obtained from these modelling results exceed the national annual average limits of 40-60 µg/m³ by 77-85% for suspended particulate matter and black smoke. Particulates emissions as observed from the HYSPLIT model platform indicates that emission sources south of Port Harcourt contribute vastly to the particulate load across the lower atmosphere of Port Harcourt and environs especially during the night time and early hours of dawn. It is thus crucial that active measures and workable solutions be evolved to safeguard the air quality of the city.

black soot, HYSPLIT model, particulates