Elemental Contents of Spinach and Lettuce from Irrigated Gardens in Kano, Nigeria

Abstract

One way analysis (ANOVA) was used to analyze a large dataset of elemental levels of two vegetables – spinach ( Amaranthus cruentus ) and lettuce ( Lactuca sativa ) grown around River Jakara in Kano, Nigeria using data generated during 12 months of monitoring Ca, K, Mg, Na, (essential bulk elements) Cu, Zn, Cd, Ni, Cr, Co, Pb and Fe (trace/heavy elements) concentrations collected at three designated sites. The concentrations of the elements showed insignificant differences between sites but significant differences between some months. The soil was implicated as the major source of the elements. The concentrations of the trace/heavy metals exceeded those of the international permissible limits which pointed to the contamination of the vegetables. The mean concentrations of the elements occurred in the magnitude of Ca > Mg > K > Na > Fe > Zn > Pb > Co > Cr > Cu > Ni > Cd and Ca > Na > K >Mg > Fe > Zn > Pb > Cr > Co > Cu > Ni > Cd in the spinach and lettuce respectively. The continued consumption of these vegetables by the inhabitants of Kano and its environs present a public health risk with regards to their concentrations with heavy metals. It is therefore recommended that the relevant organ of government should find an alternative farmland for the farmers within the catchment area of River Jakara where unpolluted soil can be utilized for the production of the vegetables.