Iranian Journal of

Background and Objective: Landfills as municipal solid waste are considered as the source of pollution. The present study aimed to assess the ecological risk of heavy metals in Tehran landfill soil and the adjacent residential area.
Materials and Methods: Having consulted with the specialists and considered the waste processing facilities, 12 sampling points were selected and sampled in four seasons. Soil samples were digested using HNO₃: HClO₄: HCl: HF. The levels of metals were measured using ICP-OES which further applied for the calculation of ecological risk. Kolmogorov-Smirnov, Kruskal-Wallis, and Pearson correlation coefficient analyses were run to determine the significant differences between metals concentrations in various seasons and sampling points. 
Results: Metal concentration showed to follow theorder: Al > Fe > Mn > Zn > Cr > Pb > Cu >Ni > Co > As > Cd. Kruskal-Wallis results and pairwise comparison showed a statistically significant difference between metal concentrations across sampling points and seasons, especially in rainy seasons. Pearson correlation coefficient displayed a strong relationship between the mean concentrations of Cu - Pb, Cu - Zn, and Pb - Zn with obtained values of 0.932, 0.874, and 0.883, respectively. Cu exhibited the highest contamination factor at the compost and fermentation sites (13.2 and 9.89, respectively). The geo-accumulation index proved the anthropogenic sources of pollution. The potential ecological risk index (ERI) for the sampling sites ranged from 67.3 to 154, with the order of Cd > Cu > Pb > Ni > As > Cr > Zn > Co > Mn. 
Conclusion: Due to the obtained moderate to severe ecological risk and exceeded background concentrations of heavy metals, it can be concluded that metal changes and soil pollution are both affected by landfill activities.

Background and Objective: Today, soil and water pollution with heavy metals is one of the major challenges around the world. The aim of this study is to investigate the contamination of soils around a lead and zinc mine.
Materials and Methods: In the summer of 2019, 100 soil samples were taken from the mine vicinity and the characteristics of texture, acidity, salinity, calcium carbonate, organic matter and heavy metals chromium, cobalt, zinc, lead and cadmium were measured. Pollution indices including pollution factor (PI), enrichment coefficient (EF), geoaccumulation (Igeo), toxicity probability (MERMQ), contamination load (PLI), background enrichment (PIN), pollution security (CSI) and Nemerow index (PINemerow) ) Were calculated. Correlation between soil variables and determination of metal origin were determined using Pearson correlation and principal component analysis (PCA) analysis.
Results: The average concentrations of chromium, cobalt, zinc, lead and cadmium were obtained as 92, 21.33, 453.98, 351.24 and 4.28 mg/kg, respectively. The metals pollution evaluated based on PI, EF and Igeo indices were moderate for chromium and cobalt, considerable for zinc and significant for lead and cadmium. The results of MERMQ, PLI, PIN, CSI and PINemerow indices showed high soil contamination with heavy metals. According to the PCA test, the elements lead, zinc and cadmium are in a group with high correlation with each other that are of anthropogenic origin. Chromium and cobalt with a correlation of 88% also showed the same geological origin.
Conclusion: mining activities should be done with more caution and measures should be taken to reduce pollution.