Environmental and human risk assessment of heavy metals at northern Nile Delta region using geostatistical analyses

Abstract

Present study aims to assess the possible toxic metal hazard of Pb, Cd and Fe in street dust and soil on environment and human health at the northern Deltaic region of Egypt using spatial and statistical analyses. To achieve this aim, 13 different sites were sampled for street dust and soil to represent various residential, industrial and agricultural activities. Unsupervised classification of multispectral Landsat OLI image (March 2021) helped to identify the sampling sites. Heavy metals were evaluated using environmental and human health risk indices incorporated in a GIS environment through geostatistical techniques. Multivariate analyses were demonstrated for further interpretation including principle components analysis (PCA), Canonical correlation analysis (CCA) and cluster analysis (CA). The average metal concentrations in street dust for Pb, Cd and Fe were 0.57, 0.07 and 435.92 mg/kg, however in soil were 0.61, 0.08 and 1098.30 mg/kg, respectively. The mean value of Cd and Pb in soil was higher than street dust while the reverse was reported for Fe. Spatial distribution maps showed that the high levels of metals in street dust were observed in the southern parts of the study area due to industrial activities and automobile emissions. The risk assessment exhibited that the area suffers from serious metals pollution particularly Cd. Human risk assessment indicated that derma is the main exposure route that harmfully affects the human health. Exposure to the pollutant through the three pathways is higher for Pb than Cd. The values of hazard quotient (HQ) followed the next trend; Fe > Pb > Cd. The measured cancer risk was negligible in the investigated area. Statistical analysis of PCA and CCA showed that industrial and agricultural activities contribute to the occurrence of heavy metals.