Seasonal variation and uptake pattern of heavy metals in maize

The detrimental impact of heavy metals on human health necessitates a focus on their contamination in the food chain. Heavy metals possess carcinogenic, mutagenic, teratogenic, and endocrine-disrupting properties. The objective of the study was to ascertain how Zn, Pb, Cd, Ni, Co, Cu, Cr, and Hg are accumulated in the roots and grains of maize samples cultivated under the Kano River Irrigation Project during both wet and dry seasons production and subsequently compare the levels of these heavy metals with the recommended permissible limits established by FAO/WHO. Additionally, the research sought to employ Translocation Factors to examine the uptake pattern of heavy metals in maize during the two growing seasons. Maize samples were procured from 10 different locations within the irrigation scheme during 2022 wet season and 2023 dry season harvests. The samples were prepared using standard laboratory protocols and heavy metals were determined using atomic absorption spectrophotometer. The heavy metals accumulation in maize grains was found in the order Zn>Cu>Pb>Ni>Co during wet season production. Cd, Cr, and Hg were not detected in samples collected during the wet season. It is only the concentration of Zn that exceeded the permissible limit in the samples collected during wet season production. The accumulation order during the dry season was Zn>Cu>Cr>Pb>Ni>Co>Cd. Hg was not detected in all the maize grain samples. The concentrations of Zn, Pb, Cd and Cr exceeded permissible limits in maize grains samples collected during dry season production.