The soils and leaves of fluted pumpkin (Telfairia occidentalis), African spinach, "Green" (Amaranthus hybridus) and water leaf (Talinum triangulare) were collected as randomly composite samples from four (4) different study locations of two (2) each from Owo Local Government Area and Etsako-West Local Government Area. The samples were examined for heavy metal concentrations, using X-ray fluorescence (XRF) technique. Chromium (Cr), zinc (Zn), manganese (Mn), iron (Fe), titanium (Ti), strontium (Sr) and aluminium (Al) of both water and vegetable samples were detected at higher proportions than the permissible limits of WHO/FAO and EU for soils and plants. Exceptions were obtained for Cr in SL3 (Talinum triangulare from St. Louis farm), and Zn in WB (soil from Water-Board farm), IY (soil from Iyerekhu farm) and IY3 (Talinum triangulare from Iyerekhu farm). Toxic heavy metals, such as nickel (Ni), lead (Pb), cobalt (Co), cadmium (Cd) and copper (Cu) were not detected in both soil and vegetable samples. Generally, the concentrations of the metals in the soil and vegetable samples followed the same decreasing order: Al>Fe>Ti>Mn>Sr>Cr>Zn. The Cr concentrations varied from

54.72 to 191.52 mg/kg among the soil samples and from 0.00 to 280.44 mg/kg among the vegetable samples. The concentrations of Zn were higher in the vegetable samples than the water samples, ranging from 0.00 to 184.74 mg/kg for soil samples and from 0.00 to 795.17 mg/kg for vegetable samples. Generally, Mn concentrations were higher in the tissues of the vegetable samples than in the soil samples except for slight deviations observed in SL1 (Telfairia occidentalis from St. Louis farm), SL2 (Amaranthum hybridus from St. Louis farm) and OL2 (Amaranthum hybridus from Osuma Layout farm). Iron (Fe) was the most abundant nutritionally essential metal in both soil and vegetable samples, ranging from 22089.07 to 64282.61 mg/kg in the soil samples and 2354.96 to 29950.57 mg/kg in the vegetable samples. Titanium (Ti) concentrations were more predominant in the soil samples than the vegetable samples. The peak (719.10 mg/kg) and least (118.44 mg/kg) Sr concentrations were observed in the OL (Osuma Layout farm) and WB (Water- Board farm) soils respectively, which bioaccumulated, in the same trend, in their corresponding Telfairia occidentalis samples. The Al concentrations ranged from 48333.29 – 75021.09 mg/kg in the soil samples and 30984.10 – 63407.34 mg/kg in the vegetable samples. All the vegetable samples had significant differences in the transfer factors of metals relative to the availability of same metals in the soil, ranging from 0.00 to 9.47. Manganese (Mn) had the peak transfer factor (9.47) in WB3 (Talinum triangulare from Water-Board farm) followed by 9.33 observed in WB1 (Telfairia occidentalis from Water-Board farm). The vegetable samples were recommended for possible application in phytoremediation of polluted soils.

1.1 Background of the Study
It is well known that a balanced diet is essential in maintaining good health. Hence, the nutritional value of foods is an important aspect that should be considered especially with respect to metal intake such as iron, calcium, magnesium, potassium, sodium, selenium, manganese, copper, chromium and zinc. Iron being required for the haemoglobin; calcium for relaxing the central nervous system; magnesium to prevent muscle spasms; potassium and sodium for electrolyte balance; selenium has a number of functions including deactivating heavy metals from external exposure; manganese and copper are linked to superoxide dismutase (SOD): chromium stabilizes blood sugar and zinc is important in the healing of wounds. On the other hand, excessive heavy metal accumulation in soils is of concern in agricultural production due to the adverse effects on food quality. Heavy metals are among the major contaminants of food supply and may considered the most important problem to our environment (Radwan and Salama, 2006). Heavy metals are persistent and non- biodegradable, have a long biological half-lives and they can be bio accumulated through the biologic chains: soil-plant-food and seawater-marine organism-food leading to unwanted side effects (Shawi, 1999). So, the presence in high amount of heavy metals in environment represents a potential danger for human health and for environment due to their extreme toxicity. Although some of the heavy metals such as Zn, Mn, Ni and Cu act as micronutrients at lower concentrations, they become toxic at higher concentrations.

The use of urban wastewater for irrigation has been going on for a long time now and the major driving forces of this practice include water scarcity, easy availability and wastewater as a source of plant nutrients (Carr, 2003). In many semi-arid and arid regions of the world, fresh surface water is usually only available in sufficient quantities during the rainy season. Water for irrigation is required for the long dry season. Groundwater may be expensive to access because of low water tables that translate into the high costs associated with drilling wells and pumping the water (Cofie et al., 2004).

Irrigation with urban wastewater in and around cities in many developing countries is a wide spread reality (Bradford et al., 2003) and the city of Accra in Ghana is not an exception. An average of 280 million m3 of wastewater is generated daily in the country and wastewater irrigated urban farming takes place in open spaces close to water sources. The practice of open space urban farming is intensive, all-year round and market-oriented.

Vegetables constitute essential components of diet for the provision of protein, vitamins, iron, calcium and other nutrients, which are usually in short supply (Thompson and Kelly, 1990). Vegetables also act as buffering agents for acidic substances obtained during the digestion process. A mixture of municipal and domestic wastewater is used for vegetable production in some parts of Accra. These water sources contain heavy metals which in certain concentrations can be toxic to consumers of produce cultivated using this wastewater. Living organisms require trace amounts of some heavy metals including copper, iron, manganese and zinc as are micronutrients which are necessary for proper physiological development. In appropriate amounts, they are essential for plants, but their excessive quantities may cause some disturbances in development of plants and result in their depressed quality. Studies have shown that continuous use of wastewater containing heavy metals for crop production tends to accumulate these heavy metals in the soil and it becomes bioavailable to crops with time (Toze, 2004). Vegetables, especially leafy crops grown in heavy metals contaminated soils, accumulate higher amounts of metals than those grown in uncontaminated soils because of the fact that they absorb these metals through their leaves (Al Jassir et al., 2005).

Research shows that wastewater carries appreciable amount of heavy metals (Pescod, 1992). Household effluents, drainage water, business effluents, atmospheric deposition and traffic related emissions transported with storm water carry a number of pollutants that enrich the urban wastewater with heavy metals (Oliveira et al., 2007). The use of wastewater for irrigating agricultural lands in Ghana is on the increase particularly in peri-urban areas of Accra, Kumasi and Tamale (Agodzo et al., 2002). From a general survey among open-space farmers carried out in 2002, it was found that about 84% of nearly 800 farmers farming in and close to Accra and almost all 700 farmers in Tamale used wastewater for irrigation, at least during the dry seasons (Agodzo et al., 2002).

Heavy metals are present in soils as natural components or as a result of human activities. Metal-rich mine tailing, metal smelting, electroplating, gas exhausts, energy and fuel production, intensive agriculture, and sludge dumping are widespread human activities which contaminate soils and aqueous streams with large quantities of toxic metals (Seward, 1990). Heavy metals are often harmful to humans and other life forms, as they can cause cancer, blindness, loss organ function, severe illness, and death (Alysia, 2009) Heavy metal pollution of aqueous streams, soil, and sediments is a major environmental problem globally. A number of studies from developing countries have reported heavy metals contamination in wastewater and wastewater irrigated soils (Z. H. Cao, 2000). Metals-accumulating plants are directly or indirectly responsible for much of the dietary uptake of toxic heavy metals by humans and other animals. While some heavy metals are essential, excessive accumulation in living organisms is toxic. All heavy metals at high concentrations have strong toxic effects and regarded as environmental pollutants (T. V. Nedelkoska, 2000). Due to population explosion and industrialization, most farm land has become habitable area and as such, most farming activities have been shifted to river bank.

Adamawa metropolis has not been left out from the aftermath effect of industrialization. Studies by Nwaedozie (1998) and Federal Ministry of Environment Report (2002) on the River Adamawa have shown considerable increase in load of pollutants. River Adamawa is a major source of water supply to the Adamawa city. The river basin is a booming crop farming area in both dry and raining seasons. The bank of River Adamawa is predominantly used for peasant vegetable crop farming of lettuce, cabbage and dry season fresh corns. Fertilizers, herbicides and insecticides are used on these crops – and are eventually washed into the river via surface run off. Most of the industries (Textile factories, NNPC Refinery and Peugeot Automobile Assembly Plants among others) located in the southern part of the city derive their water requirements from the river and discharge their wastes directly into the river (Federal Ministry of Environment, 2002). Trade wastes (from auto mechanics, metal fabrication/finishing and abattoirs among others) are also directly or indirectly discharged into the river. Domestic sewage and refuse also found their way into the river from many settlements along the river via leaching, direct discharge and surface run off. These suggest that there is every possibility of contamination of water, sediments and fish of River Adamawa by heavy metals since industrial effluents and municipal wastes are known to contain high amounts of heavy metals (Federal Ministry of Environment, 2002).

Heavy metal contamination may be occurred due to irrigation with contaminated water, the addition of fertilizers and metal-based pesticides, industrial emissions, transportation, harvesting process, storage and/or sale. Crops and vegetables grown in soils contaminated with heavy metals have greater accumulation of heavy metals than those grown in uncontaminated soil (Marshall, 2007). Plants take up metals by absorbing them from contaminated soils as well as from deposits on parts of the plants exposed to the air from polluted environment (Khairiah, 2004; Chojnacha, 2005). In general, food is the main exposure route and human beings are encourage to consume more fruits, which are a good source of vitamins, minerals, fiber and also beneficial to their health. Unfortunately, these foodstuffs contain both essential and toxic metals over a wide range of concentrations. (Radwan and Salama, 2006). It has been reported that nearly half of the mean ingestion of lead, cadmium and mercury through food is due to plant origin (fruit, vegetables and cereals). Moreover, some population groups seem to be exposed, especially vegetarians, since they absorb more frequently ‘tolerable daily doses’ (Islam, 2007). Dietary intake of heavy metals through contaminated fruits may lead to various chronic diseases. (Duruibe, 2007) suggested that biotoxic effects of heavy metals depend upon the concentrations and oxidation states of heavy metals, kind of sources and mode of deposition. Lead and cadmium are among the most abundant heavy metals and particularly toxic. The excessive content of these metals in food is associated with etiology of a number of diseases, especially with cardiovascular, kidney, nervous as well as bone diseases. (WHO, 1992, 1995 and Salama, 2006).

Other metals such as Zn and Cu are essential for important biochemical and physiological functions and necessary for maintaining health throughout life, however, higher concentrations of Zn can cause impairment of growth and reproduction (Nolan, 2003). Zinc deficiency results in a variety of immunological defects whereas copper deficiency is characterized by anemia, neutropenia and skeletal abnormalities (Prentice, 1993; Linder and Azam, 1996). Keeping in view of the potential toxicity, persistent nature and cumulative behavior as well as the consumption of fruits, there is necessity to test and analyzed these food items to ensure that the levels of these contaminants meet the agreed international requirement. Although heavy metals contamination in foodstuffs have been carried out for decades in most developed countries (Intawongse and Dean, 2006; Pennington, 1995; Milacic and Kralj, 2003). Fruits accumulate heavy metals in their edible and non-edible parts from ground water and soil. Food safety issues and potential health risk make this as one of the most serious environmental concerns (Singh, 2010). During the last decades, the increasing demand of food safety has stimulated research regarding the risk associated with consumption of foodstuffs contaminated by heavy metals, pesticides and /or toxins (D’Mello, 2003). Everyday people are being encouraged to consume more fruits. Thus there has been escalation in the growth of fruits in the urban and rural areas of Nigeria to meet the domestic consumption as well as international markets, hence, a large population at risk (Bempah, 2011). The present work deals with the quantification of heavy metals (iron, calcium, magnesium, potassium, sodium) concentrations in selected fruits sold in local markets in Adamawa Metropolis.

1.2 Statement of the Problem
Potentially harmful metal contents in soils may come not only from the bedrock itself, but also from anthropogenic sources like solid or liquid waste deposits, agricultural inputs, and fallout of industrial and urban emissions (Wilson and Pyatt, 2007). Excessive accumulation in agricultural soils may result not only in soil contamination, but has also consequences for food quality and safety. So, it is essential to monitor food quality, given that plant uptake is one of the main pathways through which heavy metals (HMs) enter the food chain (Antonious and Kochhar, 2009).

Wastewater plays complementary role in vegetable cultivation; however, irrigation with untreated wastewater can represent a major threat to public health, food safety, and environmental quality. Wastewater irrigation of vegetables and fodder may serve as the transmission route for heavy metals in the human food chain (Delgado et al., 1999).

Continuous use of wastewater for irrigation also leads to an increase in heavy metal content of the soil which leads to increase in plant uptake and contamination of ground water as a result of leaching of heavy metals (Delgado et al., 1999). Metals are persistent pollutants that can be biomagnified in the food chains becoming increasingly dangerous to human and wildlife. Assessing pollutants in different components of the ecosystem has become an important task in preventing risk to natural life and public health.

Though heavy metal contamination of soil resulting from wastewater irrigation is a cause for serious concern due to the potential health impacts of consuming contaminated produce, little work has been done to explore the impact this practice has on the concentration of heavy metal in soil and vegetable crops in Adamawa and Nigeria at large.

1.3 Justification
Minerals are divided into two groups Essential and Trace minerals, which is related to the quantity required and found in the body, the former being present in the largest amounts. Theses essential metals are the macro metals: Calcium, Magnesium, Potassium, and Sodium. Calcium is responsible for strong bones and teeth and accounts for ninety percent of the calcium in the body whereas the other one percent is circulating in fluids in order to ionize calcium. The metal’s function is related to transmitting nerve impulses; contractions of muscles; blood clotting; activation of some enzyme reactions and secretion of hormones Magnesium has many roles including supporting the functioning of the immune system; assists in preventing dental decay by retaining the calcium in tooth enamel; it has an important role in the synthesis of proteins, fat, nucleic acids; glucose metabolism as well as membrane transport system of cells. Magnesium also plays a role in muscle contraction and cell integrity. Potassium and sodium work together in muscle contraction nerve transmission. Sodium is important in muscle contraction and nerve transmission Sodium ions are the main regulators of extra cellular fluid and volume. These are particularly important for health promotion and prevention of disease.

Some trace metals include: copper, chromium, iron, manganese, molybdenum selenium, zinc. Copper has the role of assisting in the formation of haemoglobin, helping to prevent anemia as well as being involved in several enzymes. Chromium function is related to stabilizing blood sugar levels with respect to insulin required for release of energy from glucose. Iron is the central metal in the haemoglobin molecule for oxygen transport in the blood and is portion of myoglobin located in muscles. Manganese is one of the co-factors in a number of enzymes as is molybdenum. Selenium has several roles such as regulating the thyroid hormone as well as being part of an enzyme that protects against oxidation. Selenium has also been reported as assisting in deactivating heavy metals. Assessment of heavy metals found in orange, watermelon and pineapple

1.4 Aims and Objectives
The main aim of this study is to access the heavy metals deposited in vegetables and fruits irrigated with waste water in Gulak Madagali Local Government, Adamawa State.

Specifically, the study sort to:

• To collect relevant data on heavy metals deposited in the waste water in Gulak Madagali Local Government.

• To access the quantity of heavy metals deposits in the vegetables and fruits irrigated with the waste water in Madagali Local Government.

• To compare the quantity of heavy metal deposit in vegetable and fruits irrigated by the waste water.

1.5 Hypothesis
The following null hypothesis will be tested at 0.05 level of significant

H01: There is no significant difference in heavy metals deposit of vegetables and fruits irrigated by waste water

H02: There is a significant difference in heavy metals deposit of vegetables and fruits irrigated by waste water

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