Heavy Metals Uptake in Maize Grains and Leaves in Different Agro Ecological Zones in Uasin Gishu County

Abstract

Maize grain is the second most vital food after wheat to humans and forms an important part of a human diet due to its nutrients. In Kenya, it is estimated that one out of every two acres of land put to crop production is under maize crop. Maize can also be fed whole to livestock (grazed or chopped and ensiled). Due to increased demand and the need for higher productivity, farmers have adopted modern farming methods which include use of fertilizers, pesticides, compost manure, and irrigation. Uses of these products elevate amounts of heavy metals in the soil. Such heavy metals such as lead (Pb) and cadmium when taken up by plants accumulate in the plants becoming toxic at high levels. It is essential to monitor these levels in grains and leaves to ensure they do not exceed the WHO permissible limits. This study aimed at monitoring the levels of heavy metals uptake in maize (Zea mays) grains and leaves is within permissible levels. Level of heavy metals in maize grains from different ecological zones in UG County had mean concentration of Zn 0.122, Cd 0.03, Cu 0.111, Co 0.04, and Pb 0.33 mg/kg. These results were below WHO standards except for Cadmium, Co, and Pb which were slightly higher than recommended standard. The study also found that maize leaves had mean concentration of Zn 0.115, Cd 0.04, Cu 0.117, Co. 0.041 and Pb 0.323 mg/kg. The results were below WHO standards except Co and Pb which had slightly higher levels than the recommended WHO standards. The analytical results from this study provided important baseline statistics on the concentration of selected heavy metals in maize grains and leaves besides being an important assessment of environmental pollution in rural areas where maize farming is predominant.