Abstract:
Assessment of heavy metal pollution due to tobacco farming: Cd, Pb, Co, Cu, Cr, Mn, Ni and Zn was conducted in Migori county, Kenya using Atomic Absorption Spectrometry (AAS). Grid sampling was employed in which 50 m2 of land was randomly selected in each of two sampling areas and was divided into ten equally sized grid cells of 5 m2. The study also investigated the effects of these heavy metals on the fertility indices of the soil such as PH, nitrogen, available nitrogen, phosphorous, available phosphorous and organic carbon. Data obtained was subjected to analysis of variance (ANOVA) and correlation analysis using the Pearson moment correlation coefficient technique. The mean concentrations of heavy metals was 14.5 µg/g for Pb, 9.2 µg/g for Cd, 99.7 µg/g for Zn, 33.4 µg/g for Cu, 25.0 µg/g for Cr, 43.6 µg/g for Ni and 14743 µg/g for Mn. The Contamination Factor revealed that the sites were moderately contaminated, the Pollution Load Index showed Mabera to be more contaminated with PLI = 1.15 while Masaba had 1 .05 and finally Geoaccumulation Index showed the two regions to be moderately contaminated. Significantly positive correlation was found to exist between nitrogen, potassium, total organic matter, nitrates and total phosphorus at P = 0.01. Significantly positive correlation was also found to exist between lead and nitrogen; nitrates and copper; chromium and cobalt; potassium and manganese, TOC; nitrogen and nitrates, TOC and total phosphorus. Chromium and zinc; manganese and total phosphorous, TOC; potassium and total phosphorous. The findings in this study will serve to create awareness of the extent of heavy metal pollution to Kenyan policy makers in the mitigation of heavy metal pollution, as it is barely monitored.
