توصيفگر ها :
كارخانه كاشي و سراميك , كارخانه سيمان , پارامترهاي پذيرفتاري مغناطيسي , شاخص غنيشدگي , شاخص زمينانباشت , آناليز خوشهاي , خاك شهري
چكيده انگليسي :
A great increase in population and the higher rate of urbanization, the use of motor vehicles, the construction of factories and the use of fossil fuels have caused a significant increase in heavy metals in the environment. The purpose of this study was to determine the effect of different land uses on the concentration of heavy metals and magnetic receptivity in the surface soils of urban areas, ceramic tile factory, gray and white cement manufactories and street dust in Naeein city, Isfahan Province. For this purpose, 20 soil samples from urban area of Naeein, and 32 soil samples from the soils surrounding each of the factories were collected from the depth of 0-10 cm. Total concentration of Zn, Mn, Fe, Co, Pb, Cr, Cu and Ni in all samples were measured by an atomic absorption spectrometer following the extraction with 6N nitric acid. The results showed that the mean content of Zn, Cr, Cr and Ni in urban soils, Fe and Co in soils around the cement factory and Mn concentration in soils around the tile and ceramic factories were higher than those in other land uses. This difference in concentration can be attributed to the influence of the type of land use and parent material of the region on the total concentration of metals. Also, the concentration of Co, Pb, and Cu in street dust were higher than that in urban soil and the average concentration of Zn, Mn, Fe, Ni and Cr in soil samples were higher than that in street dust samples. The average magnetic susceptibility at low frequency in the soil around the tile and ceramic factories was higher than that in other land uses and the percentage of frequency-dependent magnetic susceptibility in urban soil was higher than that in other land uses. Also, the average value of magnetic receptivity at low frequency in street dust was higher than in urban soil, and the average value of frequency-dependent magnetic susceptibility in urban soil was higher than that in the street dust. The results of the correlation analysis showed a positive and significant relationship (p<0.01) between all heavy elements with each other in all land uses and street dust, and positive and significant correlation coefficients between Zn, Pb, Cr and Ni in urban soils. The results of the correlation analysis showed that for the whole dataset, there were negative and significant relationships between metal contents and magnetic susceptibility which attributed to the presence of sedimentary parent material and the release of diamagnetic minerals such as calcite from the tile and cement factories. The results of nonlinear multivariate regression analysis showed that EC, clay, silt, and Mn content could account for 54% of the variability in magnetic susceptibility in the surface soil of the whole study area. Moreover, Fe, Cu, Mn, and Co accounted for 55 % variability of magnetic susceptibility in street dust. According to the enrichment factor, Zn, Mn, and Ni in soils of all land uses and street dust probably have combined origin (anthropogenic and geogenic), while Co in street dust and, to some extent, in tile factory and Ni in cement factories with enrichment factor greater than 10 show higher anthropogenic contribution. The results of the cluster analysis showed that the possible origin in urban soil for the metals of Zn, Pb and Cu were mostly anthropogenic, and Fe, Ni, Co and Cr had combined sources.
