Master of Science (M.Sc.) Theses and Dissertations

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Browsing Master of Science (M.Sc.) Theses and Dissertations by Author "AREGBESOLA Joshua Akin"

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    Assesssment of the effectiveness of lead removal from helianthus annuus L. remediated soil using amaranthus hybridusL .
    (The Institute Of Ecology And Environmental Studies, Faculty Of Sciences, Obafemi Awolowo University., 2023) AREGBESOLA Joshua Akin
    This study determined the Physical and chemical properties of a Pb remediated soil and assessed the growth response of Amaranthus hybridus cultivated on this soil. It also determined the nutrients and Pb uptake by A. hybridus from the remediated soil. These were with a view to providing information on the effectiveness of Pb removal by Helianthus annuus from a Pb polluted soil. The study was carried out in the screenhouse of the Faculty of Pharmacy, Obafemi Awolowo University (OAU), Ile-Ife. The study was a follow-up on a previous study in which the topsoil was polluted to four levels of Lead concentrations. A total of 72 polythene bags, each containing 10 kilograms of Pb remediated soil obtained after this study showed the presence of Pb. The polythene pots had also received three rates of organic fertilizer; 0, 5 and 10 t ha-1, and two rates; 0 and 2 t ha-1 of Urea fertilizer, and four levels of Pb: 0, 400, 800, 1200 mg Pb kg-1 arranged in a complete randomized design. The seeds of A. hybridus earlier obtained from the Faculty of Agriculture, OAU, Ile-Ife were sown at six seeds per pot, and thereafter watered with distilled water to field moisture capacity. Growth parameters such as number of leaves, plant height and stem girths were collected at 3, 4, 5 and 6 weeks after sowing (WAS) using standard methods, and thereafter terminated. The harvested aboveground biomass of the plant was weighed and oven-dried to constant weight. The pre- and post-cropped remediated soils, and dried plant samples were analyzed to determine their properties, including Pb and Zn using standard methods. Data collected were subjected to descriptive and inferential statistics and the significance in their mean values of growth parameters and soil properties were separated at 95% confidence limit using Tukey‘s Multiple Range Test. The pH of the pre-cropped remediated soil ranged from 5.57 ± 0.02 to 7.43 ± 0.04. The soil organic Carbon and total Nitrogen values ranged from 3.90 ± 0.20 to 33.90 ± 0.30, and 0.30 ± 0.10 to 2.90 ± 0.10 g kg-1, respectively. The initial concentrations of Pb and Zn ranged; 75.16 ± 0.02 to 170.50 ± 8.04 and 3.81 ± 0.02 to 9.54 ± 0.03 mg kg-1, respectively. At harvest, the stem girth of A. hybridus ranged from 0.39 ± 0.06 to 2.81 ± 0.55 cm, while the aboveground biomass yield ranged from 0.11 ± 0.06 to 36.41 ± 9.47 and 0.06 ± 0.03 to 3.70 ± 1.28 g pot-1 for the wet and dry weight, respectively from the pot without Pb contamination, but with 2 t ha-1 of Urea and 5 t ha-1 of organic fertilizer. These growth parameters were significantly (p < 0.05) higher than the values obtained during the repeat experiment. The highest values obtained for Pb and Zn concentrations in the shoots of A. hybridus were 0.50 ± 0.01 and 3.05 ± 0.05 mg kg-1, respectively; which were higher than WHO/FAO permissible limits of 0.005 and 0.60 mg kg-1 for Pb and Zn respectively. The study concluded that Amaranthus hybridus cultivated on Lead remediated soil removed and transported Lead to aboveground biomass of the plant which could eventually enter into the food chain of humans, if ingested.