Potential Toxic Elements (PTEs) Assessment in Soil and River Sediment Within Kwalkwalawa Irrigation Floodplain of Sokoto State, North-Western Nigeria

Abstract

The concentration of potential toxic elements (PTEs) in soil and river sediments within the Kwalkwalawa floodplain area of Sokoto State, Nigeria, was assessed and analysed using the following environmental pollution indices: contamination degree (Cd), geoaccumulation index (I-geo) and enrichment factor (EF). The PTEs assessed include; Fe, Cu, Cd, Pb, Ni, As and Cr. They were measured using Microwave Plasma Atomic Emission Spectrometry (MP-AES). Most parts of the floodplain are actively used for irrigation farming, and the application of agrochemicals can potentially lead to the enrichment of PTEs in soil and river sediments. The computed Cd for the soil and river sediment is 0.35 and 0.46, respectively. These low values indicate that the soil and sediments are unpolluted with PTEs, although the concentration of the PTEs in the sediment is significantly higher than that of the soil. It was also observed that the average Cd of soils (0.42) within the irrigated area of the floodplain is significantly higher than the average Cd of soil (0.12) in the unirrigated area. The other environmental pollution indices computed, i.e., I-geo and EF, all agree with the no pollution status deduced from the Cd analysis. Thus, it can be concluded that although the soil is unpolluted at the moment, the irrigation practice is actively enriching the soil in most parts of the floodplain area with PTEs, and therefore, regular monitoring is recommended.