Investigation of Selected Heavy Metal Ions in Irrigation Water, Soil and Managu (Solanum Nigrum) from Homahills, Homabay County, Kenya

Abstract

Levels of selected heavy metals of Mn, Cd, Pb, Zn, Fe and Co were evaluated in irrigation water, soil and managu (Solanum Nigrum) from Homahills, Homabay County, Kenya. The samples were collected purposively and randomly then transported to KALRO Kericho to be analysed using Inductive Coupled Plasma Optical Emission Spectroscopy. Descriptive statistics and t-test analysis for the heavy metal concentrations were done using SPSS Version 21, transfer factor was also calculated. The levels of heavy metals detected in irrigation water were; 0.89, 0.01, 0.18, 0.35, 4.20 and 0.04 mg/L for Mn, Cd, Pb, Zn, Fe and Co respectively. The overall concentration of heavy metals detected in soil under irrigation were; 315.56, 1.00, 13.00, 19.17, 59.05 and 12.50 mg/kg for Mn, Cd, Pb, Zn, Fe and Co respectively. The overall levels of heavy metals detected in Solanum Nigrum under irrigation were 10.16, 5.23, 4.02, 41.42, 479.56 and 11.41 mg/kg for Mn, Cd, Pb, Zn, Fe and Co respectively. Using paired t-test, the mean heavy metals level recorded in irrigated Solanum Nigrum from two Sub locations were significantly different (p < 0.05) in Mn, Pb, Zn and Co but not significantly different in Cd and Fe. The results revealed that levels of Cd, Mn, Fe and Pb in soil and Solanum Nigrum were above the FAO/WHO limit. These levels pose risks to the consumers rendering them not safe for consumption. Therefore, regular monitoring for these metals in food is vital in ensuring consumption of safe food and avoiding bioaccumulation in the food chain.