Geospatial analysis, source identification, contamination status, ecological and health risk assessment of heavy metals in agricultural soils from Qallin city, Egypt

Abstract

49 surface soil samples were collected from Qallin farmland, Nile Delta, Egypt, during winter 2018, to appraise the extent of contamination and to examine the associated potential risks (both ecological and health risks) due to ten heavy metals (HMs) (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn). To determine the risk area for each metal and deduce its potential sources of emission, geospatial mapping and multivariate statistical analysis were integrated. Pollution and ecological risk indices were also calculated. Moreover, noncarcinogenic and carcinogenic health risks, due to soil exposure through ingestion, inhalation, and dermal contact, were appraised for adult and children. The consistency in results obtained—via geospatial mapping and multivariate statistical analysis—facilitated identifying the potential sources for the investigated metals in Qallin’s farmland. Overall, three potential sources were concluded for the investigated metals; (1) lithogenic (included Al, Co, Mn, Fe), (2) anthropogenic due to agronomic practices and transportation (included Cu, Zn, Cd, Pb), and (3) atmospheric dry deposition with natural and anthropic origins for Ni and Cr, respectively. Results of contamination assessment showed that Qallin’s soil exhibited very high contamination, as well as a moderate level of pollution, with the highest contributions were for Cd followed by Cr. Over and above, the environment exhibited very high ecological risk where 88.39% of the risk was attributed to Cd pollution. Accordingly, urgent soil protection measures are needed to prevent any further Cd pollution. Concerning the health risk assessment results, the total non-carcinogenic risk value in children was higher than adults as well as than the safe limit of one, indicating that children may be subjected to high non-carcinogenic risks. On the other hand, the total lifetime cancer risk values in adult males and females were within the safe range, indicating that Qallin residents are safe from carcinogenic risks.