Bioaccumulation of heavy metals in the different parts of maize cultivated in soils irrigated with different quality of water

Abstract

The present study investigated the bioaccumulation and distribution pattern of heavy metals in maize organs cultivated in soils with varied levels of heavy metals. Additionally, the potential human risk due to the ingested levels of heavy metals detected in maize grains was studied. Nine locations, representing soils irrigated by different water sources of fresh and wastewater, were selected. Heavy metals analysis was carried out using inductively coupled plasma method with optical emission spectrometry (ICP-OES). The results revealed that heavy metals of Ni, Cu and Cr were the most abundant elements detected in the studied soil sites followed by Pb and Cd. Values of the total uptake of heavy metals by maize from the soils irrigated by wastewater were 3.3-5.6 folds those of soils irrigated by fresh water. Soils irrigated with wastewater showed bioaccumulation factor (BF) averages for heavy metals in maize at the following descending order: Pb > Cd > Ni > Cu > Cr. Meanwhile, soils irrigated by the river or groundwater exhibited BF values arranged as Cu = Ni > Cr > Cd > Pb. The accumulation pattern of heavy metals in maize organs was arranged as: roots > leaves > stem > cob > grains. As well, except for Ni, levels of all heavy metals, in maize grains, were lower than the permissible limits set by FAO/WHO. Notably, the rank order of hazard quotient to heavy metals was Cd > Pb > Ni > Cu > Cr; with low potential risk for public health.