Assessment of heavy metal contamination in the soils of an agricultural field near the Bargny cement plant (Senegal)

In this study, the concentrations of heavy metals Fe, As, Mn, Cr, Ni, Zn, Ti, and Cu were measured in soil samples from an agricultural site located near a cement plant that has been operating in the area for several decades. The results of the analyses showed the following decreasing ranking of average concentrations : Fe > Ti > Cr > Ni > As > Mn > Zn > Cu. The maximum concentrations of As (54.79 mg/kg) and Cr (148.86 mg/kg) exceeded the limits set by the World Health Organization and the Food and Agriculture Organization of the United Nations (FAO). The analysis of correlations between the concentrations of the different heavy metals studied indicated anthropogenic origins for the metallic elements As, Zn, and Cr. The agricultural field showed moderate enrichment by Ni, significant enrichment by Cr, and very high enrichment by As, with enrichment factors of 4.725, 8.315, and 20.599, respectively. Approximately 33.33% of the study area had an As concentration exceeding the permitted limit. The individual pollution index (PI) indicated moderate As pollution of the agricultural field. The overall Nemerow pollution index (P _N ) placed the study site within the precautionary range for the trace metal Cr. Regarding As, the site was in the area of ​​severe pollution, with a P _N of 3.097. However, the potential ecological risks were low.