Assessment of heavy metal accumulation in dust and leaves of Conocarpus erectus in urban areas: Implications for phytoremediation

This study investigated the spatio-temporal variation of heavy metal concentrations in roadside dust and its correlation with heavy metal content in roadside plant leaves. Sixty re-suspended dust samples were collected from six locations during two seasons (dry and wet). Simultaneously, leaf samples of Conocarpus erectus were collected from the same locations. The samples were analyzed using an atomic absorption spectrophotometer to determine the concentrations of As, Cu, Fe, Cd, Pb, and Ni. The pH and conductivity of the dust were also analyzed using a glass electrode. The mean concentrations (μg/g) of heavy metals in the dust ranged from 0.337 to 6.34 for As, 10.60–55.39 for Cu, 542.17–1453.45 for Fe, 0.193–1.026 for Cd, 11.82–52.56 for Pb, and 10.19–29.27 for Ni in different seasons. Similarly, the concentrations of heavy metals in the leaf samples ranged from 0.031 to 1.70 for As, 6.90–13.19 for Cu, 263.09–576.16 for Fe, 0.299–1.33 for Cd, 0.019–17.82 for Pb, and 2.09–7.015 for Ni in different seasons. The correlation between heavy metal concentrations in different seasons was examined using Pearson's and Spearman's correlation methods. To compare the bioaccumulation ability, bio-concentration factors (BCF), comprehensive bio-concentration index (CBCI), and metal accumulation index (MAI) were calculated. The Conocarpus erectus MAI was consistent across different locations and seasons (24.49 ± 0.149). Based on CBCI, the bioaccumulation capacity of heavy metals they were ranged from 6.57 to 12.83 in the dry season and from 5.84 to 10.24 in the wet season. These findings provide valuable insights into the distribution and accumulation of heavy metals in roadside dust and plant leaves, highlighting the potential of Conocarpus erectus as a bio-accumulator for heavy metal pollution in urban environments. The results can be utilized to develop appropriate strategies for environmental management and pollution control in areas affected by vehicular pollution.