Thesis Abstract

The level of accumulation of heavy chemicals in the leaves, stem and roots of Corchorusolitorius seedlings irrigated with sewage (Sewage effluent) and tap water to maturity respectively was investigated. Prior to irrigation, water quality indicators and physico-chemical properties of the two water sources were analysed. The experiment, a completely randomized design was carried out in a screen house in the Botanic Garden of the Department of Plant Science and Biotechnology, University of Nigeria, Nsukka and lasted for four months. The results showed that sewage water had higher values of biochemical oxygen demand (BOD), chemical oxygen demand (COD), and temperature than tap water. The results also showed that tap water had higher values of dissolved oxygen (DO) and transparency than sewage water. The results further showed that sewage water had higher values of the analysed physico-chemical properties than tap water. Again, it showed that sewage water enhanced better seedling growth than tap water. Cadmium, Mercury, Zinc, Copper, Lead and Arsenic accumulation in the leaves, stem and roots were higher in seedlings irrigated with sewage water when compared with those irrigated with tap water. The results further showed that the accumulation of heavy chemicals in the leaves, stem and roots of the seedlings irrigated with broth water sources, (Sewage and tap) were higher than the accepted standard of the Federal Environmental Protection Agency (FEPA). Based on the results obtained, it is recommended that continued production of leaf vegetables off-season using sewage water be avoided, because of possible health hazards posed by continued consumption of such vegetables.

Thesis Overview