Urban Heavy Metal Pollution Monitoring Using Ficus nitida as a Bioindicator

This study examined the seasonal and spatial distribution of heavy metals (Cd, Pb, and Ni) in relation to environmental parameters in five regions of Greater Cairo, Egypt (Helwan, Al-Azhar, Al-Orman, Al-Orman Center, and Al-Moqattam) between 2023 and 2024 using Ficus nitida as a bioindicator. Leaf and soil samples were taken periodically and tested for heavy metal levels, growth factors, chlorophyll, NPK, and moisture content. Concentrations of Cd, Pb, and Ni were highest at Helwan, the industrial site, reaching 0.22 mg/kg, followed by Al-Azhar, a high-traffic urban area, with 0.12 mg/kg, particularly during the summer season. In contrast, the lowest concentrations (0.03 mg/kg) were recorded at Al-Orman Center and Al-Moqattam, both characterized as low-traffic residential zones. A positive correlation was observed between heavy metal concentrations in Ficus nitida leaves and those in the corresponding soils. Additionally, the minimum leaf area was recorded at Helwan during winter, followed by the Al-Azhar region, with values of 36.2 cm² and 41.7 cm², respectively. Reductions in chlorophyll content and nutritional composition were linked to heavy metal levels. Ficus nitida may function as a trustworthy bioindicator of the environmental heavy metal contamination and the health of urban ecosystems, and it accurately reflects soil and air pollution levels.