Investigating the Spread of Soils Pollution and Pollution Sources Originating from Tehran in Rural Districts of Qal'ehno and Kahrizak (Rey Township, Tehran, Iran)

Soil, as one of the key systems of the earth, provides goods, services and resources for humankind. So, if it is being damaged, the foundation of an important part of human needs will be collapsed. The purpose of this study is to investigate the amount of pollutants and pollutant sources in the surface soils of Qal'ehno and part of Kahrizak district villages in south of Tehran.

The research has been done in autumn 2017 through an analytical-descriptive method. The data used in the analysis are based on the measurement of contaminants in the samples. 144 sample points were selected by grid method and soil samples were taken and measured, then the results were entered in the GIS. We used IDW method for interpolating the point and introducing zoning maps. The analysis is based on separated and overlapped maps of the spatial distribution of pollutants in accordance with quantitative data and the conditions of the contamination sources.

Data analysis and zoning maps showed that the concentration of barium, cobalt, chromium, copper, nickel, lead, uranium and zinc in the region soils was higher than the permitted limits and the concentration range of the pollutants studied (in mg / kg) and the concentration area of each of them was as follows: lead from 6 to 168 and the highest in the northeast, cadmium from 0.6 to 2 and the highest in the north-west, arsenic ranges from 0.6 to 13.4 and the highest in the northeast, nitrate from 80 to 700 with the highest in the south-west, organic carbon from 0.6 to 3 and maximum concentration in the north-west, and finally, TPHs with an average of 0.051 and concentration of the highest densities in the center of the region.

Although soil contamination is high in the whole area, the severity of density is generally higher in those parts that use more untreated wastewater in irrigation. The permeability channels through which sewage is passed, the use of untreated wastewater in irrigation the oil refining industry and the storage and distribution of oil products have affected soil contamination.