Investigation of heavy metals accumulation in the soil and pine trees

Abstract

Background: Human activities related to workshops in the cities contribute to the release of heavy metals into the environment, which pose serious risks to the environment and to human health. The aim of the present study was to evaluate the concentration of lead (Pb), iron (Fe), and manganese (Mn) in the pine trees and soil in various land uses of Birjand city, Iran. Methods: The sampling stations were randomly selected from different land uses including parks, streets, carwashes, car repair shops, and car smooth shops in Birjand city. The pine trees (skin and leaves) and soil samples were collected from 15 stations located at different and uses in 2017. To determine the concentration of heavy metals, atomic absorption spectrometer (Contr AA 700) was used. Results: It was revealed that the mean concentration of Pb, Fe and Mn in residential soil was 1.79, 419.39, and 30.76 mg/kg, respectively. Moreover, the Pb, Fe, and Mn concentration in pine skin and leaves was 0.63 – 0.18, 23.05–9.84, and 10.05–3.13 mg/kg, respectively. The geo-accumulation index (Igeo) mean of the study areas demonstrated a descending trend for Fe (16.31 mg/kg) <Mn (8.86 mg/kg) <Pb (0.41 mg/kg). Pb showed the highest transfer factor in the parks and streets followed by Mn and Fe. In the car repair and smooth shops, the highest transfer factor pertained to Pb and the lowest one pertained to Fe. The statistical analysis indicated that there was a significant difference in the Fe and Mn concentrations among various land uses (P < 0.05). Conclusion: According to the results, the soils of car repair and smooth shops as well as carwashes in Birjand are becoming polluted by Pb, Fe, and Mn. Although, it does not threaten the city ecosystem, but with passage of time, these measures will be accumulated due to the soil alkalinity and will reach critical levels.