Uptake of copper and cobalt by pumpkin (cucurbita maxima) and chinese cabbage (brassica oleracea) irrigated with contaminated water on sandy loam and clay loam soils.
| dc.contributor.author | Volk, John | |
| dc.date.accessioned | 2024-12-04T13:04:43Z | |
| dc.date.available | 2024-12-04T13:04:43Z | |
| dc.date.issued | 2019 | |
| dc.description | Thesis of Doctor of Philosophy in Soil Science. | |
| dc.description.abstract | Pumpkins and Chinese cabbage are widely grown in peri urban areas with different soil types in Zambia using waste water which is potentially contaminated with heavy metals like copper and cobalt. The objectives of this study were to establish the effect of loading rates of heavy metals on sandy and clay loam soils and establish factors that influence transmission their uptake by pumpkin and Chinese cabbage when grown on sandy and clay loam soils when irrigated with water contaminated with Cu and Co. A green house study in which pumpkin and Chinese cabbage were grown in pots with sandy loam and clay loam soil was used. Irrigation water comprised contaminated water that had four levels of concentrations of Cu and Co in them and a control of fresh water. Comparing the chemical properties of soil before and after the experiment gave the capacities of the soils to adsorb Cu and Co in them. The fractions of Cu and Co measured in the test soils established the form in which the two elements were adsorbed in soils and provided possible explanations of transmission of heavy metals to plants from water and soil. Concentration of Cu and Co in tissues of pumpkin and Chinese cabbage established their capacity to accumulate the two metals. Yields of crops, concentration of Cu and Co in plant tissues and soil tested the relationships that explained the effect of levels of contaminants in irrigation water on crops and soils. The study found that clay loam adsorbed significantly higher (p<0.05) Cu and Co than sandy loam soil. The results show significantly higher (p < 0.05) concentrations of Cu and Co in plant tissue in sandy loam than clay loam soils. It was established clay loam retained more Cu on the organic and exchangeable fractions than sandy loam soil. Clay loam reduced significantly (p<0.05) the transmission of Cu and Co to crops. Lack of significant effects (p<0.05) of concentrations of Cu and Co in plant tissue on yield implies that crops that appear healthy may contain high levels of heavy metals and unhealthy for human consumption. The study confirms that soils with higher clay and organic matter adsorbs higher amounts of heavy metals which could potentially be used in immobilizing the same elements and prevent the contamination of crops grown on them. The lower adsorption capacity of heavy metals by sandy loam would potentially result in higher transmission of heavy metals from water to crops. The concentrations of Cu found in Chinese cabbage (180 mg/kg) and pumpkin (116 mg/kg) were 6 times and 4 times higher respectively, than the normal range for Cu which is estimated to be around 1-30 mg/kg. Without significant negative effects on yield, or physiology from contamination, vegetables may have higher levels of heavy metals that could be unhealthy for human consumption. It is recommended that further studies seek to address understanding of how a wider range of elements each contributed to crop production, and how the various soil fractions of these elements influence availability and their uptake and yield of crops. | |
| dc.identifier.uri | https://dspace.unza.zm/handle/123456789/8986 | |
| dc.language.iso | en | |
| dc.publisher | The University of Zambia | |
| dc.title | Uptake of copper and cobalt by pumpkin (cucurbita maxima) and chinese cabbage (brassica oleracea) irrigated with contaminated water on sandy loam and clay loam soils. | |
| dc.type | Thesis |