INAA-Based Assessment of Elemental Contamination and Ecological Risks in Sediments Associated with Local Open-Site Fertilizer Blending Activities in Kankara, Northwestern Nigeria

Open-site fertilizer blending activities can release potentially toxic and environmentally relevant elements into surrounding sediments, posing risks to local agro-ecosystems through runoff, dust dispersion and subsequent accumulation. This study employed instrumental neutron activation analysis (INAA) to determine the concentrations of nine elements (As, Cr, Zn, Co, V, Mn, U, Th and Ba) and to evaluate associated ecological risks in sediments linked to such activities in Kankara Local Government Area, Katsina State, northwestern Nigeria. Six composite sediment samples (SS1–SS6) were collected, processed and analysed. Analytical accuracy was confirmed using the IAEA-158 marine sediment reference material, which yielded recoveries of 96.6–111.2 % and Z-scores within the acceptable range (|Z| ≤ 0.96). Marked spatial variation was observed, with elevated concentrations of V (up to 241 mg kg⁻¹), Mn (up to 2615 mg kg⁻¹), Cr (up to 106 mg kg⁻¹) and Ba (up to 890 mg kg⁻¹) at sites nearest the blending operations. Contamination factors and geoaccumulation indices indicated low to moderate enrichment for several elements at these locations, while the partial potential ecological risk index based on As, Cr and Zn ranged from 3.68 to 14.35, indicating low potential ecological risk under the adopted screening framework. The localised enrichment of Mn and V, however, warrants continued monitoring. The results provide a baseline for future assessments of fertilizer-related sediment contamination in the region and underscore the need for improved containment, dust suppression and routine environmental surveillance to minimise mobilisation of potentially toxic and environmentally relevant elements into adjacent sediments and the wider agro-ecosystem.