Determination of Concentrations of Selected Metals in Tobacco Leaves and Its Farmland Soils of Assosa woreda, Benshangul Gumuz Regional state, Ethiopia

Abstract

Tobaccos are a commercial plant that naturally accumulates and concentrate relatively high levels of toxic heavy metals such as; cadmium (Cd) and lead (Pb) and essential elements like Zinc (Zn),Copper (Cu) and Manganese (Mn). Hence, the level of these metals were determined in tobacco and its farmland of AssosaWoreda, BenshangulGumuz Region, Ethiopia. The sample was collected from five different localities of tobacco farmlands of AssosaWoreda. Soil samples were collected from the top to 30 cm depth and leaves of tobacco were collected from the lower to upper part of each tobacco plant. The tobacco and soil samples were digested following the protocol of wet digestion method using analytical grade chemicals. Chemicals were used HCl, HNO3 and H2O2. One way of ANOVA and F-test were used to analyze the obtained data. The analysis of heavy metal in tobacco leaves and soil of its farm land was as certain levels of concentration of total metal content of cadmium, copper, manganese, lead and zinc of digestion was carried out by using wet digestion technique. The efficient of the digestion procedure was checked by recovery test of known concentration of standards solution of Cd, Cu, Mn, Pb and Zn were spiked in tobacco leaves and soil samples then triplicate digestion and triplicate reading was applied. Results show that the concentration values tobacco obtained were as follows: Mn range from (0,75 mg/L to 1.18 mg/L), Cu range from (0.11 mg/L to 0.21 mg/L), Zn range from (0.58 mg/L to 1.16 mg/L) Cd range from (0.008 mg/L to 0.009 mg/L) and the content of heavy metals in soil sample were Mn range from (1.59mg/L to 8.04mg/L),Cu range from (0.32mg/L to 0.38mg/L), Zn range from (0.29mg/L to 1.26mg/L) Cd was below the detection and quantification limits of the instrument and Pb ranged from (0.17mg/L to 0.31mg/L). The content of heavy metal in tobacco leaves and in soil sample is below the permissible value of WHO/FAO except the concentration Mn in the soil.