Assessment of Heavy Metals Accumulation in Lactuca sativa and Amaranthus caudatus Grown with Manure from Refuse Dumping Site in Gusau Local Government

Abstract

Local farmers nowadays gathered manure from dumped sites to grow vegetables. Due to this fact, this research was conducted to assess the health risk of growing vegetables using manure contaminated with heavy metals, by using the Atomic Absorption Spectroscopy (AAS). In this research, vegetables (Lettuce and Amaranthus) were grown on three different pots (A, B and C) that comprises the control soil, contaminated soil from dumped sites and the mixed of control and contaminated soil. The harvested vegetables were digested using wet acid method and prepared for metal analysis using AAS and the data was analyzed using Minitab version 16.0 and the results was expressed as mean ± standard deviation and the mean values were compared with World Health Organization (WHO) recommended dose. The findings revealed that Cadmium (Cd) and Chromium (Cr) exceed WHO permissible limits of 0.2mg/L and 1.3mg/L respectively. The order of accumulation varied from plant to plant. Lettuce has the following: Zn > Cr > Cd > Ni > Pb > Cu. While that of Amaranthus is: Zn > Cu > Cd > Cr > Ni > Pb. Also, in comparison with lettuce, amaranthus absorb and accumulates more heavy metals.