Sequential extraction analysis of U, Sr, V, Ni, Cr, B, and Mo in sediments from the Al-Batin Alluvial Fan, Southern Iraq

The distribution of U, Sr, V, Ni, Cr, B, and Mo in sediments of the Al-Batin Alluvial Fan in southern Iraq was investigated. A total of 18 sediment samples were collected in the study area and the clay and silt fraction was analyzed using a six-step sequential extraction method. Results of the sequential extraction were used to evaluate the potential origin and environmental impacts of the selected elements. Except for Sr, the highest average concentration of the investigated trace elements is mainly in the residual fraction with the following descending order: Cr > V > B > Ni > Mo > U. This suggests a geogenic origin of these trace elements. Sr occurs mainly in the acid soluble fraction due to its authigenic formation from the underlying carbonate beds. Anthropogenic pollution in the study area is restricted to agricultural activities and fertilizer application which adds B and Mo to the soil in some cases. The Sr elevation and fractionation within the sediments suggests a possibility of Sr accumulation in cultivated crops, and thus a potential risk to infants and children. High concentrations and fractionation pattern of U in three samples shows a considerable risk to the environment in certain areas.