Levels and ecological risk assessment of mineral and heavy metals in soils around Nasara Fertilizer Blending Plant, Lafia, Nigeria

Abstract

Fertilizer introduction in the right elemental proportion based on plants' nutritional needs has contributed positively to crop production. On the other hand, the leakages during fertilizer blending have contributed to excessive mineral nutrients and traces of heavy metals in the environment. These leakages contaminate water bodies or get into the food chain and bio-cumulate in tissues of living organisms with detrimental effects. This study assessed the impact of fertilizer blending on the level of some mineral and heavy metals in soils around the industrial layout using MP-AES, pollution indices in terms of the geo-accumulation index and contamination factor. The results revealed all of the mineral and heavy metals were detected in the soil in the order of abundance: Fe (10560.77±8.00 mg/kg), P (5252.17±36.15 mg/kg), K (1834.53±13.74 mg/kg), Mg (593.99±13.75 mg/kg), Mn (335.18±1.63 mg/kg), Zn (205.96±1.18 mg/kg), Pb (20.08±0.19 mg/kg) and Cd (6.51±0.06 mg/kg). There was a significant difference in soil quality, mineral and heavy metal content between the test and control soil samples (P < 0.05). The geo-accumulation index showed moderate contamination by phosphorus and strong to extreme contamination by cadmium. The contamination factor showed the soil is moderately contaminated with zinc and lead, considerably contaminated with phosphorus but highly contaminated with cadmium, a very toxic element that distributes so easily in soil and plant tissues. Hence, consumption of crops, fruits and vegetables from the area may likely be at risk. Regular monitoring and effective clean up are recommended.