Heavy Metals in Foliar Dust: Utilizing Ziziphus spina-christi Leaves in Estimating Levels of Vehicular Pollution

The study investigates the Ziziphus spina-christi leaves as bioindicators for vehicular traffic-related air pollution. The analysis primarily focused on the elevated concentration of metals built up on the leaf surface. The accumulated dust on the leaves of Z. spina-christi was analyzed for the presence of several metals, including aluminum (Al), barium (Ba), cadmium (Cd), chromium (Cr), copper (Cu), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), lead (Pb), and zinc (Zn), using inductively coupled plasma optical emission spectrometry (ICP-OES). ArcGIS was used to map the spatial distribution of metal concentrations across the study sites. The study revealed strong correlations among metals, such as Al, Cr, Fe, Cu, and Zn with vehicular traffic, whereas Ca and Mg exhibited weaker correlations. Barium showed a moderate correlation, suggesting the presence of other emission sources. The pollution load index (PLI) and contamination factor (CF) assessments indicated moderate contamination levels at the study sites, and strong inter-elemental correlations suggested shared emission sources, primarily linked to traffic-related activities. The morphological study and the spatial distribution of metal concentrations were consistent with the data obtained from the chemical analysis.