الملخص الإنجليزي
Abstract Emissions from industrial areas are one of many sources of air pollution which pose a negative impact on the atmosphere. The objectives of this study are to analyze the trends in the average monthly concentrations of the air pollutants sulphur dioxide (SO2), hydrogen sulphide, methane hydrocarbons, non-methane hydrocarbons, benzene, toluene, ethyl-benzene, and xylene, around the Mina Al-Fahal (MAF) industrial area, over a period from January to August of 2015. This was achieved by performing the Mann-Kendall rank correlation, Pearson product-moment correlation and the Spearman rank correlation methods. The other objective is to identify the bio accumulation potential of ten selected plant species at the study site, the MAF complex, which was assessed by measuring their 16 priority Polycyclic Aromatic Hydrocarbons (PAHs) and sulphate concentrations. The Sultan Qaboos University (SQU) botanic garden, a non-industrial site, was selected to be the reference site for comparison. Additionally, the MAF complex plant species were screened based on their ability to accumulate specific PAHs compounds and also based on their ability to accumulate low and high molecular weight PAHs. Lastly, the response of the plants to the pollutants was also assessed by measuring few physiological parameters (chlorophyll concentration and the photosynthetic gas exchange parameters). A statistically significant decreasing trend was found in the mean methane hydrocarbons concentrations, while increasing trend was found for the monthly mean concentrations of both toluene and xylene over the eight months period. It was observed that the mean monthly SO2 concentrations were high during the cooler months (January to March), while the hotter months (May to July) recorded low values, indicating a seasonal variation. The plant species yellow trumpet flower (Tecoma stans) followed by, paradise flower (Caesalpinia pulcherrima), tamarind (Tamarindus indica), and neem (Azadirachta indica) were found to accumulate higher amounts of PAHs. Thus, they are deemed suitable as bio-accumulators for atmospheric PAHs. Additionally, the plant species date palm (Phoenix dactylifera) followed by, hibiscus (Hibiscus sp.), paradise flower, ghaf (Prosopis cineraria), tamarind, and neem were found to accumulate higher amounts of sulphate. Thus, excluding the date palm, they are deemed suitable as bio-accumulators for atmospheric SO2. Moreover, for the MAF complex plant species, high concentrations of acenaphthene and naphthalene were found for yellow trumpet flower and tamarind, respectively. Yellow oleander (Thevetia peruviana) showed a strong accumulation capacity for acenaphthylene and pyrene. In contrast, the only PAH compound that the date palm was able to accumulate is anthracene. Both the neem and paradise flower showed a strong accumulation capacity for naphthalene and fluoranthene. In addition, a significant difference was found between the MAF complex and SQU samples in their PAHs profile patterns. The MAF complex samples were found to be more efficient in accumulating and retaining low molecular weight PAHs (two- and three-ring PAHs). While the SQU plant species were found to be able to accumulate both the low and high molecular weight PAHs (two- and six-ring PAHs). A strong correlation wasn't found between the PAHs and sulphur concentrations and between the studied physiological parameters. Analyzing the trends in the air pollution data is important for understanding the status of the air quality which will assist in an improved understanding of the air pollution situation within the MAF complex. The results of this study demonstrate that several plants grown in the MAF complex have the ability to attenuate air pollutants. Hence, growing vegetation in and around industrial areas is essential to absorb and attenuate the pollutants emitted by industries into the surrounding atmosphere.
