عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Background and objectives: Increasing industrialization and human activities intensify the emission of various pollutants into the environment. Air pollution has been considered one of the most important environmental challenges because of its effect on ecosystems and human health. Heavy metals which enter the environment from many different sources such as industrial and agricultural activities cause serious environmental risks, To reduce the negative impact of heavy metals, it is necessary to identify contaminated areas. The aim of this study was to examine selected chemical properties and concentrations of heavy metals such as iron (Fe), zinc (Zn), lead (Pb), copper (Cu), and nickel (Ni) in dust from Bushehr and Assaluyeh cities as urban and industrial areas, respectively, and also from the transect ( about 300 km) between the two cities as a non-urban area.
Materials and methods: Fifty dust samples (dry deposition) were taken from the leaves of the date palm trees at. The sampling was carried out in September 2012 at 50 sites including 15 samples from the urban area (Bushehr city), 12 from the industrial area (Assaluyeh city), and 23 from the non-urban area along the transect between the two cities. Also, fifty surface soil samples (0-10 cm) were taken from the sites adjacent to the same trees from which dust samples were collected. Then, the total concentrations of Fe, Zn, Pb, Cu, and Ni of dust and soil samples were measured by an atomic absorption spectrometer after digestion with 6N nitric acid (11, 24, 27). The relationships between heavy metals in the dust samples and their origins were determined using correlation coefficients, PCA and CA.
Results:The mean concentrations of the heavy metals in the dust from the three areas were found to be higher than those of the nearby soils except for Pb in Bushehr. A significant increase in dust Zn, Cu, and Pb concentrations was found in industrial and urban areas (Bushehr and Assaluyeh) as compared to the non-urban transect. The highest dust Cu and Pb concentrations were observed in Bushehr, but dust Zn concentration of Assaluyeh was higher than those in other areas. The two main sources of different heavy metals in atmospheric dust deposited on date palm leaves were identified based on the principal component analysis, cluster analysis and correlation coefficients. Zn, Cu, and Pb seem to have anthropogenic sources, whereas Fe and Ni in the atmospheric dust presumably derive from non-anthropogenic sources. Values of contamination factor indicate that dust in Bushehr and also in industrial area of Assaluyeh falls in considerably contaminated level in terms of Zn and Cu.
Conclusion: Increasing industrialization and human activities intensified the entering of heavy metals into Bushehr Province atmospheric. In general, implementation of environmental standards in Assaluyeh industrial zone and improvement of public transportation in Bushehr city are necessary to reduce the level of pollutants entering the atmosphere.