Assessment of the heavy metal contamination using GIS-based approach and pollution indices in agricultural soils from Beni Amir irrigated perimeter, Tadla plain, Morocco

In agricultural soils, the contamination of heavy metals has become a major source of soil pollution in the world because of intensive agriculture practices. This paper aimed to assess the heavy metal contamination in the Beni Amir irrigated perimeter in Tadla plain, Morocco, using various geoaccumulation index and Geographical Information Systems (GIS). Forty seven subsurface agricultural soil samples were analyzed for Zn, Cr, Pb, Cu, and Cd contents. The results revealed that soils were contaminated by metals having concentrations (Zn: 294.7mg/kg, Cr: 57.0mg/kg, Pb: 33.3mg/kg, Cu: 25.9mg/kg, and Cd: 1.8mg/kg) exceeding the WHO and FAO limits. Moreover, the highest metal contents were noticed around industrial areas and agglomerations. In our study area, the geoaccumulation indexes (Igeo), enrichment factor (EF), contamination factors (CF), and Load Pollution Index (PLI) are confirmed the anthropogenic sources of heavy metals. The spatial pattern for Zn, Cr, Cd, and Pb revealed that the contamination are related to the land use and to the influence of anthropogenic pollution and soil properties such as soil pH, organic matter, and clay mineralogy.