Polycyclic aromatic hydrocarbons: Measuring the air quality of three communities in Port Harcourt, Rivers State

Abstract

There are a good number of major oil-producing companies as well as numerous activities that involve the combustion of organic matter. These activities release enormous quantities of pollutants into the atmosphere and there seems to be a paucity of data that captures the concentration of pollutants in the air as well as their health implications. This study was aimed at determining the levels/concentrations of polycyclic aromatic hydrocarbons in the surrounding air of three communities in Port Harcourt, Rivers State. Rivers State houses two oil refineries, a fertilizer company, and numerous companies. Sampling was conducted using the EGASPIN 2018 sampling procedure. Air samples were collected unto sterilized filter paper from the three communities using a Bosean meter. Sample extraction and analysis were conducted using GC-FID (EPA 8270). The study was conducted over the dry and wet seasons in 2019. Dry season result showed the presence of majorly four low molecular weight polycyclic aromatic hydrocarbons - naphthalene, fluorene, phenanthrene, and anthracene; in Okrika, concentrations of were 2.766±1.429 mg/kg, 0.976±0.491 mg/kg, 0.014±0.007 mg/kg and 0.040±0.023 mg/kg respectively; in Mgbuodohia the concentrations were 0.822±0.668 mg/kg, 1.199±0.626 mg/kg, 0.008±0.004 mg/kg and 0.012±0.009 mg/kg respectively; in Chokocho the concentrations were 0.144±0.097 mg/kg, 1.074±0.738 mg/kg, 0.001±0.000 mg/kg, and 0.142±0.067 mg/kg respectively. Wet season results showed the concentration of naphthalene, fluorene, phenanthrene, and anthracene; in Okrika, the concentration was 0.271±0.034 mg/kg, 0.108±0.019 mg/kg, 0.055±0.009 mg/kg and 0.001±0.000 mg/kg respectively; in Mgbuodohia the concentrations were 0.014±0.002 mg/kg, 0.005±0.004 mg/kg, 0.009±0.002 mg/kg and 0.001±0.000 mg/kg respectively; in Chokocho the concentrations were 0.001±0.000 mg/kg, 0.001±0.000 mg/kg, 0.002±0.001 mg/kg and 0.001±0.000 mg/kg. Against the backdrop of past studies linking the concentration of PAHs to the presence of refineries and other anthropogenic human activities, the Chokocho study location was chosen as a control site. The result agrees with the premise that air around regions where there is relatively less human activity like the combustion of organic matter, tend to have lower concentration of polycyclic aromatic hydrocarbon content. The total concentrations of PAHs in the air during the dry season are 3.809 mg/kg, 2.045 mg/kg, and 1.375 mg/kg in Okrika, Mgbuodohia, and Chokocho respectively, showing Okrika to be the most polluted followed by Mgbuodohia and lastly Chokocho. Source apportionment points to petrogenic, pyrolytic, and other possible sources. The detection of just four out of the sixteen priority PAHs points to the fact that there seems to be more effect on other matrices like soil and water.