Assessment of Heavy Metal Contamination in Water, Soil and Different Varieties of Rice Grown in Nguru – Gashu’a and Geidam River, Yobe State, Nigeria.

Abstract

This research was conducted to evaluate the degree of pollution in the Nguru-Gashua-Geidam river system in Yobe, Nigeria. The investigation involved the analysis of water, soil, and multiple rice varieties collected from three distinct sites. The analytical parameters included physicochemical properties, heavy metal concentrations, and calculated pollution indices. The pH of water and soil samples were found to be within the range of 6.47 ± 0.05 —6.85 ± 0.13 and 6.00 — 7.70 respectively. The EC, Alkalinity, chloride, hardness, TDS and turbidity of the water samples were in the ranges of 2.12 ± 0.27—2.67 ± 0.35 ds/m; 67.23 + 0.43 —92.33 ± 0.58 mg/L; 0.73 ± 0.02—0.89 ± 0.08 mg/L; 26.67 + 2.31 — 35.67 ± 0.58 mg/L 1357 ± 1.08— 1708 + 1.99 mg/L and 2.23 ± 0.77— 164.20 ± 0.32 FTTJ respectively. The results demonstrated significant heavy metal contamination across the sampled environments. Water was contaminated with Cr, Fe, and Pb (exceeding NSDWQ standards), while soil was contaminated with Cr, Cu, Fe, and Pb (exceeding WHO standards). This contamination transferred into the biota, with rice grains showing elevated Cu and Zn levels above WHO limits, though rice leaves retained acceptable Cr and Zn levels. While overall contamination indices suggested low to moderate pollution levels, a high transfer factor for Pb indicated a significant pathway into plants. Collectively, the data confirm widespread contamination by the metals under investigation.