Comparative Studies of Heavy Metals and Mineral Residues in Some Farm Crops around Mining Community of Ribi, Awe Local Government Area of Nasarawa State

Abstract

This work investigated the level of heavy metals and other elements present in two agricultrural crops (millet and maize) cultivated in mining community of Ribi, Awe LGA of Nasarawa State, Nigeria. Samples were collected from four (4) different farms at the peak of rainy season (between July and August). Samples were analysed at the Chemistry Advance Research Centre, Sheda Science and Technical Complex (SHESTCO) Gwagwalada Abuja. The atomic absorption spectrometer (thermo Scientific, ice3000AA02134104v1.30) was used. All analyses were performed in triplicate. Data were analysed using Minitab Statistical software (16.0). In the rainy season, millet had higher concentration of all the residues quantified except in cadmium which was more concentrated in maize (0.11mg/L). In other heavy metals, lead was 2.83mg/L in millet and 2.54mg/L in maize. Copper was 1.32mg/L in millet and 0.83 in maize. Magnesium was 10.47mg/L in millet and 10.43mg/L in maize. In the dry season, maize had higher concentrations of lead (2.67mg/L), copper (0.925mg/L), nickel (0.134mg/L) and iron (1.688mg/L) whereas cadmium, magnesium, and zinc were more in millet than in maize. Dry season millet was higher in some residues than the control millet. Some millet residues were higher in rainy season than the control level. In millet, lead was highest in raining season (2.831 mg/L) whereas copper and cadmium were very high in dry season (0.586 mg/L and 0.213mg/L respectively), even more than the control. Magnesium residues recorded the highest values among all heavy metals present in millet. Magnesium also had the highest concentration among the residues present in maize in the following order: rainy season (10.43mg/L) > dry season (9.33mg/L) > maize control (9.23mg/L). Iron was more concentrated in the control maize (2.65mg/L) than in both dry and rainy seasons whereas zinc recorded higher seasonal concentrations (0.44mg/L) than the control level (0.46mg/L The values of Pb, Zn, and Ni in millet and maize are above the WHO’s standard guideline while other residues are within or below the regulatory limits. Mining activities taking place around the in the study location might have impacted negatively on the safe consumption of agricultural crops cultivated by farmers.