Quantifying Emissions of Volatie Organic Organic Compounds and Ground Level Ozone on Petroleum Filing Stations in Urban West, Zanzibar

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The State University of Zanzibar
The aim of this study was to quantify emissions of volatile organic compounds and ground level ozone on petroleum filling stations in urban west, Zanzibar. Between August and November 2019, ambient concentrations of volatile organic compounds (VOCs), and ozone were quantified from 14 petroleum filling stations in urban and west districts. These stations are allocated in urban west region Zanzibar. Using BH-4S Portable multi-gas detector, in situ measurement was conducted to quantify the concentrations of VOCs and ozone from each site twice a day (before noon and afternoon) for two separate sessions (August to September and October to November 2019). The analyzed data revealed temporary and spatial variations of measured parameters. VOCs range were 22.9 ppm and 32.3 ppm and ozone range was 4.2 ppm and 9.7 ppm for the first and second phase respectively. VOCs and ozone concentrations showed direct relationship between one another as we witnessed the good correlation (R2 = 0.625) between these two parameters. Possibly, ground level ozone could be triggered by the presence of volatile organic compounds under the presence of nitrous oxide (NOx) and sunlight. Besides that, the average VOCs levels from the selected sites ranged from 24.3 ppm at Kwerekwe3 to 47.2 ppm at Kinazini for first phase. For the second phase, average VOCs levels ranged from 38.7 ppm at Kwerekwe1 to 71.05 ppm at Kiembe Samaki. In other hand, average ozone concentration ranged from 0.6 ppm at Gulioni to 4.8 ppm at Kwerekwe1 for the first phase. While second phase average ozone concentration ranged from 4.5 ppm at Kwerekwe1 to 14.2 ppm at Kwamchina. Generally, VOCs and ozone levels at petroleum filling stations were higher compared to accepted levels provided by international, and local organizations and agencies. Moreover, during second phase, levels of measured parameters were higher than those taken from first phase, presumably to temperature variation. The most important concern is to reduce VOCs level at petrol filling stations by installation of vapour recovery system in all the stations and activating the systems at the time of gasoline discharge. This could probably help to combat the formation of ground level ozone at the stations.
Concentration of volatile organic compounds, Emissions of volatile organic compounds, Ground level ozone at petroleum filling stations in urban west region Zanzibar
Saadat Soud Mohamed