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 both 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.

Title page
Table of Contents
List of Plates
List of Tables

1.0       Chapter One
1.1       Introduction
1.2       Classification of Corchorusolitorius
1.3       The Objectives of this Study

2.0       Chapter Two
2.1       Literature Review

3.0       Chapter Three
3.1       Materials and Methods
3.2       Collection, Identification and Confirmation of Materials
3.3       Pre-Nursery
3.4       Nursery Proper
3.5       Transplanting of Seedlings from the Nursery
3.6       Main Experiment
3.7       Data Collection and Analysis
3.8       Determination of Water Quality
3.8.1    Temperature
3.8.2    Transparency
3.8.3    pH
3.8.4    Dissolved Oxygen (DO)
3.8.5    Biochemical Oxygen Demand (BOD)
3.8.6    Chemical Oxygen Demand (COD)
3.9       Preparation of Samples for Chemical Analysis
3.9.1    Copper Determination
3.9.2    Zinc Determination
3.9.3    Mercury Determination
3.9.4    Arsenic Determination
3.9.5    Iron Determination
3.9.6    Cadmium Determination
3.9.7    Lead Determination
3.9.8    Magnesium Determination
3.9.9    Potassium Determination
3.9.10  Calcium Determination
3.9.11  Phosphate Determination
3.9.12  Nitrogen Determination
3.9.13  Chloride Determination

4.0       Chapter Four
4.1       Results
4.2       Water Quality Indicators
4.3       Physico-chemical Analysis
4.4       Some Growth Parameter
4.5       Accumulation of Toxic Chemical Elements in the Leaves of C. olitorius
4.6       Accumulation of Toxic Chemical Elements in the Stem of C. olitorius
4.7       Accumulation of Toxic Chemical Elements in the Roots of C. olitorius
4.8       Accumulation of the Toxic Metals in the three plant parts (Leaf, stem and root) ofC. olitorius: a comparison

5.0       Chapter Five
5.1       Discussion and Conclusion

1.1          Introduction
Globally, water has been a major requirement for the growth and development of biotic life. Water has for long exerted strong influence on the choice of place for human settlement. Of all human activities, agriculture and industrial activities have been identified as the highest consumer of water (Nweze and Chimboh, 2003). With time, increase in population and sophisticated advancements in man’s industrial sectors have resulted in drastic scarcity of available natural/clean water. Hence, the use of waste water either in the raw state or purified form in agricultural activities, especially in the off season vegetable crop production and ornamentals became imperative for decades in Europe, North America and Australia (Dolgenet al., 2004). Following the success of propagating vegetable crops, ornamentals and lawn maintenance, using waste water, the practice became recognized in many other countries like India, China, Middle East etc. (Hampet al., 1976).

In the developing countries like Nigeria, Ghana, Cameroun, Togo, waste water is used in vegetable production, especially in the dry season/off season. Waste water used includedomestic waste water and sewage effluent (Nweze and Chimboh, 2003). In Egypt, acute shortage of natural/clean water has resulted in the development of alternative sources of obtaining water for agricultural production. Bashiret al., (2006) reported that in Egypt, due to increase in population and agricultural activities, the use of waste water and sewage effluent has progressively increased particularly in the urban cities. The authors reported that waste water is deposited on the ground to enable its reclamation for further reuse. They also reported the reclamation of about four million m3 and two million m3 water in Cairo and Alexandria respectively and the salvaged water could be used to irrigate about 300,000 fadama for vegetable production

Many authors have appraised the use of sewage water in vegetable production but did not emphasize the health hazards posed by consuming such vegetables (Dolgenet al., 2004, Bashir et al., 2006, Singh and Agrawal, 2010, Maryam, 2011). Dolgenet al., 2004 reported the benefits of irrigating agricultural crops with sewage water to include; provision of chemical nutrients like nitrogen, phosphorus, boron, manganese, copper and zinc to the crops. Maryam (2011) pointed out that the effects of these chemical mineral nutrients in rapid growth of vegetables have stimulated interest in the use of sewage effluent in vegetable production. The author further reported that irrigating vegetables with waste water of whatever origin could pose health hazards due to the absorption and accumulation of heavy metals in the produced crop, particularly vegetables.

In the developed countries, with large-scale sewage treatment plant, water salvaged from sewage is properly treated before recycling for various uses (Batstone and Keller, 2003). In the developing countries, Imhoff treatment equipment in use for sewage water extraction have facilities that were below international standard because the tanks are exposed to the air, while the drying beds and the oxygenated ponds may not be functioning effectively (Llyod, 2000). The type of vegetables produced during off-season using sewage effluent (Water) for water supply varies from one locality to another because of the level of revenue generated. In the South Eastern Nigeria, popular vegetables produced during off-season include:Telfairiaoccidentalis, AmaranthusviridisandCorchorusolitorius, while in the South Southern Nigeria, the most popular off-season vegetable is Taliniumtriangulare. In the Northern states, off-season vegetables include Lactucasativum, Daucuscarota andBrassicaoleracea. These vegetables often appeal to the eyes due to their freshness. They (vegetables) are variously used in preparing delicious foods eaten in restaurants, various eating spots like motor parks, market, roadsides (Sold by food vendors), Universitycommunities and in big national and international hotels. Generally, people are ignorant of the source of water with which these vegetables were irrigated. Reports that sewage effluent- irrigated vegetables absorb and accumulate heavy metals, becomesnecessary that the extent of the heavy metal accumulation in the edible parts of the vegetables should be made known, with the view of ascertaining the safety of human health.

Of all the vegetables produced off-season using sewage and or waste water, CorchorusolitoriusLquickly comes to mind and thus is selected for this study, because of its popularity in most diets, particularly in the South Western states of Nigeria......

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