Concentration of heavy metals in leachate, soil, and plants in Tehran’s landfill: Investigation of the effect of landfill age on the intensity of pollution

Heavy metals are one of the important pollutants in landfill leachate. Plants and soil near the landfill may be contaminated by leachate. In this study, by evaluating the heavy metals in the leachate of two landfills and the soil and plants near them, the amount of pollution caused by the leachate in the environment around the landfills in Tehran was investigated. This study was conducted in three stations, soil and plant samples were prepared according to a specific protocol. Also, three indexes including PI, PI(Nemerow), and BF were used to interpret the results. The results showed that the concentration of total metals in the old landfill leachate and new landfill leachate was only 12% different and was 24.13 mg/L on average. In the new landfill leachate, iron had the highest concentration among metals, which was 22.94 and 17.01 mg/L in two samples. In the old landfill leachate, the concentration of manganese was 15.71 mg/L, which was the highest among the studied metals. The concentration of heavy metals in the soil of the old landfill was 24.6% lower than the concentration of metals in the soil of the new landfill. In all samples, the highest metal concentration in the soil was related to manganese, which was 33.65–34.14 mg/L. Cadmium had the lowest concentration in soil compared to other metals. The concentration of total metals in the studied plants was 29–60 ppm. The PInemerow for studied stations was 0.1711, 0.1708, and 0.1463. The highest PI in the case of lead was observed at the second station equal to 0.54. The highest BF in case of Atriplex Undulata was more than 6 and related to cadmium, while the highest BF in case of Atriplex Cinearea was more than 3.5 related to cadmium. This study showed that the soil and plants of the landfill were contaminated with heavy metals under the influence of leachate, and the ability of plants to uptake and accumulate metals can be used to manage soil pollution near the landfill.