Ecological risk assessment of heavy metals in the surface soil of selected parks in Tehran, based on sampling at year 1400

The results of this study show that the ecological risk assessment index shows the low risk of most sampling areas, while the highest risk is related to the Shahr Park and Mellat Park, respectively. They also have a high ecological risk compared to other metals, cadmium and lead. The enrichment index also shows a significant accumulation of cadmium, lead and zinc and to some extent iron, chromium and nickel in soil samples of the study area due to human activities. Cadmium has the highest index of geochemical accumulation in surface soil samples of Tehran parks. Maximum cadmium levels were observed at stations in the Shahr Park, which are based on the classification of highly contaminated soils. Based on the results of statistical analysis and the enrichment coefficient of potential emission sources are identified as follows:Large amounts of copper, cadmium, lead and zinc enrichment coefficient indicate that human resources are the main source of these metals. Significant positive correlation and behavioral similarity of nickel and chromium with the mentioned metals show that nickel and chromium have the same emission sources with this group. Although these two metals have common sources with other metals, the low coefficients indicate that nickel and chromium may also have natural resources in relation to the surface soil samples of the sampling area.