Browsing by Author "Said, Alfred"

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    Hexavalent chromium mobility and distribution behavior in riparian agricultural tropical soils: a column experiment
    (Springer Nature, 2022) Kwikima, Muhajir M.; Said, Alfred
    Ingestion has been identified as a significant source of hexavalent chromium exposure in humans. The metal exposure in a community fed by vegetables cultivated along the Msimbazi River's riparian area has been studied by ascertaining its bioavailability in soil. Through column experiments, the mobility and distribution characteristics of hexavalent chromium (Cr(Vl)) in soils were examined. To achieve saturation flow conditions, influent Cr(VI) solutions of 0.26, 0.52, and 1.04 mg/L were introduced from the upper side of the three columns, respectively, until the effluent solute concentration equaled the influent concentration. The findings demonstrate that the predominant process governing Cr(VI) mobility and dispersion in soils is the reduction to trivalent chromium (Cr(III)), followed by adsorption. The Cr(VI) concentration distribution on the column at the end of the experiment was reasonably even across the columns, with a little drop with depth, which is assumed to be related to the leaching of other minerals that impede Hexavalent Cr reduction/adsorption (VI). According to the findings, the increase in Cr(VI) concentration is proportional to the solute's adsorption in the soil. Furthermore, the time it took for the effluent-influent solute concentration equilibrium to be reached was proportional to the rise in influent Cr(VI) concentration. Given that reduction is the dominant process, vertical mobility, transportation, and dispersion of Cr(Vl) in soils may be argued to have a minimal environmental impact. However, due to the apparent soil's high adsorption capacity for Cr(VI) and hence its bioavailability, the metal may contaminate crops planted in the vicinity. Increases in variables that influence the oxidation of Cr(III) to harmful Cr(VI) in the soil, such as pH, may have a significant deleterious effect.