Bolu şehir merkezinde gaz kirleticilerinin alansal olarak pasif örnekleme yöntemiyle izlenmesi

In this study, spatial evaluation of inorganic gaseous pollutants (SO2, NO2, and O3) and organic pollutants, BTEXs compounds were evaluated by passive sampling method at three different regions (high altitude villages, roadside and city center) in Bolu. Nitrogen dioxide (NO2), sulfur dioxide (SO2) and ozone (O3) are among important inorganic gaseous air pollutants and organic air pollutants benzene, toluene, ethylbenzene, xylene (BTEXs) are the most important VOCs because of their high potential to exert health effects. These compounds have negative effects on the human health and ecosystem. The aim of this study is to observe the levels and distribution of these inorganic (NO2, SO2 and O3) and organic (BTEXs) air pollutants in Bolu atmosphere and also to determine the ozone formation potentials and estimation of cancer risk assessment of BTEXs compounds. Passive sampling which is the most convenient method for the determination of spatial distributions of the pollutant concentrations was performed in two seasons. The winter (January- February 2017) and summer (July 2017) sampling campaign were conducted in Bolu plateau including city center, high altitude forested areas, towns and villages. NO2-SO2 passive sampler and O3 passive sampler which were developed by Anadolu University Environmental Engineering Department Air Pollution Research Group were used. Tenax-TA tubes were used as BTEX passive sampler. Inorganic passive samples were analyzed by using ion chromatography method and organic (BTEX) samples were analyzed with thermal desorption-gas chromatography-mass spectroscopy system. Analysis results were converted into pollution maps by MapInfo Professional 7.5 SCP in order to interpret the spatial distribution. High ozone concentrations were observed in rural-forested sites while low ozone concentrations were measured around the TEM and D-100 roads. Ozone is generally expected to be higher in summer season due to high intensity of solar radiation than in winter season but in the study ozone concentrations were observed higher in winter season than in summer season. High ozone formation rates in the rural and forested areas were observed due to the presence of biogenic volatile organic compounds (BVOCs), NOx and sunlight. It has been known that BVOCs, which are released from trees, are more reactive than their anthropogenic forms because of the double bond (pi bond) (Abelson, 1988). The spatial distribution of BTEX pollution maps had demonstrated that the highest concentrations were found at the major roads because of heavy traffic. NO2 and SO2 are the major determinants in the evaluation of the pollution sources such as traffic and domestic heating. NO2 concentrations were observed to be higher around TEM, D-100 highways and in the city center. NO2 concentrations had been found to be higher in summer season than in winter season. The widespread usage of natural gas in the city center made SO2 concentrations to be low in the city center, while higher levels had been obtained in the semi-rural sites because of coal usage as domestic heating. It was seen that the summer values were higher than the winter values because the plateau settlement starts in summer season and due to low temperature in these areas, people use coal for residential heating. Non-carcinogenic and carcinogenic air pollutants levels were detected using the exposure calculations assessment. It was observed that the values of lifetime cancer risk (LTCR) were the greater than 0.0001 for benzene for villages. Benzene compound had not the risk level because it was not at the definite risk level (1x10-4) for the other regions (roadside and city center). On the other hand, it was found that the values of noncarcinogenic risk ratio, the hazard quotient (HQ) was lower than 1 for all BTEXs compounds. These risks were accepted as negligible because they were smaller than 1. As a result of this, non-carcinogenic risk values were at safe level.