Accummulation And Bioaccessibility Of Heavy Metals In Some Root Tubers And Soil In Selected Communities In The Ashanti Region Of Ghana
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Date
2018-04
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KNUST
Abstract
The presence of metal contaminants in agricultural soils or lands and subsequent uptake of heavy metals by food crops pose serious risk to human health. The study assessed the levels of toxic metals -arsenic, chromium, copper, iron, manganese, nickel, and zinc- in soils and some edible root tuber crops in the Ashanti region to evaluate the potential human health risks associated with exposure to these metals. Concentrations of heavy metals in the 154 samples were initially screened using field portable x-ray fluorescence spectrometer prior to confirmation on an inductively coupled plasma-mass spectrometer. The mean metal concentrations analyzed in the various samples were in the order; As ˂ Cu ˂ Ni ˂Cr ˂ Zn ˂ Mn ˂ Fe for cassava and cocoyam, As ˂ Cu ˂ Zn ˂ Ni ˂ Cr ˂ Mn ˂ Fe, As ˂ Zn ˂ Cu ˂ Ni ˂ Cr ˂ Mn ˂ Fe As ˂ Cu ˂ Ni ˂ Cr ˂ Mn ˂ Fe and Cu ˂ As ˂ Ni ˂ Cr ˂ Z n ˂ Mn ˂ Fe for yam, sweet potato, cassava peels and soil respectively. Soil pH and electrical conductivity ranged between 5.30 to 9.17 and 37.8 µS/cm to 4020 µS/cm respectively. The contamination indices indicated low to moderate contamination. The bioaccumulation factor of these heavy metals in foodstuffs from soil indicated that cassava peels had higher capacity to absorb zinc and iron gave the lowest capacity of absorption. Arsenic recorded the highest value in terms of target hazard quotient (THQ) followed by nickel and chromium, the least value. Comparing the THQ values for adults and children, results for children were higher than that of adults which indicates that children are more likely to express the effect than adults.
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A THESIS SUBMITTED TO THE DEPARTMENT OF CHEMISTRY, COLLEGE OF SCIENCE, KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY, IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF MASTER OF PHILOSOPHY IN ANALYTICAL CHEMISTRY