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Kwame Nkrumah University of Science and Technology (2007)

Modelling Cadmium and Lead Uptake from Irrigation Water by Some Vegetables through Transpiration in the Semi-Deciduous Forest Zone of Ghana

Mensah, Ebenezer

Titre : Modelling Cadmium and Lead Uptake from Irrigation Water by Some Vegetables through Transpiration in the Semi-Deciduous Forest Zone of Ghana

Auteur : Mensah, Ebenezer

Université de soutenance : Kwame Nkrumah University of Science and Technology

Grade :  : DOCTOR OF PHILOSOPHY 2007

Résumé partiel
Heavy metal contamination of agricultural soils is a major concern to food production all over the world. Agricultural soil heavy metal contamination is from wastewater irrigation, application of sewage and air deposition from the atmosphere and is of great importance because of its implications for human health. Systemic health problems can develop as a result of excessive accumulation of dietary heavy metals such as Cd, Pb, Ni, Cu and Cr in the human body. A study was carried out at the Kwame Nkrumah University of Science and Technology (KNUST) in Ghana using water to which Cd and Pb had been added to irrigate cabbage, carrots and lettuce. Cadmium solutions of concentrations 0, 0.05 and 0.1 mg L-1 and Pb solutions of concentrations of 0, 30 and 50 mg L-1 were prepared and used to irrigate the crops. Kinetics of Cd and Pb concentrations in irrigation water were studied by preparing a 1:1 ratio of the sandy loam soil from the experimental site and irrigation water and shaken for 8 hours. The results showed that Cd concentration stabilized within the first 1 hour and the partition coefficients (Kd) for the 0.05 and 0.1mg L-1 irrigation water concentrations were 4 and 11.5, respectively. For Pb solutions the partitioncoefficients (Kd) were not constant but varied with time with values ranging between 0 and 6.94 after 6 hours of shaking. Moisture content of soil is known to influence the release of metals in soil solutions, however agricultural soils are generally of low moisture content. It was found from the study that the release of metals in soils was non-linear resulting in variation in the metal distribution coefficient. Soil Ca and dissolved organic carbon (DOC) concentrations gave a better prediction of soil Cd concentration than soil solution pH. Plant and soil samples from the experimental fields were collected for laboratory analysis.

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