INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 1, ISSUE 11, DECEMBER 2012 ISSN 2277-8616 124 IJSTR©2012 www.ijstr.org Heavy Metals Accumulation In Cabbage, Lettuce And Carrot Irrigated With Wastewater From Nagodi Mining Site In Ghana G. A. Boamponsem, M. Kumi, I. Debrah Abstract:- The heavy metal pollution is a major environmental problem especially in mining areas. The study was carried out to quantify heavy metal levels and compare their accumulation in the stems, leaves and roots of Lactuca sativa (lettuce), Brassica oleracea L. var capitata (cabbage) and Daucus carrota var sativa (carrot) irrigated with wastewater from Nagodi mining site. Pot experiment was conducted using surface soil (0-20cm). Differential accumulation and translocation of copper (Cu), lead (Pb), iron (Fe), manganese (Mn) cadmium (Cd) and zinc (Zn) in the root, stem and leaf of vegetables were investigated using atomic absorption spectrophotometer. Cd concentration in the various parts of D. carrota was in the range of 0.070 -0.090 mg/Kg. The highest concentration (17.30 mg/Kg) of Mn was found in the stem of L. sativa. Fe was highly absorbed (139.6 mg/Kg) by B. oleracea roots. The highest concentration (0.221 mg/Kg) of Cu was found in D. carrota roots and the highest concentration (35.35 mg/Kg) of Zn was found in the roots of Brassica. Cd accumulation in L. sativa and B. oleracea was below detection limit (< 0.002 mg/Kg). Pb absorbed by the three genotypes was below detection limit (< 0.005 mg/Kg). Though heavy metals were absorbed, their concentrations were below WHO/FAO recommended limits; vegetables cultivated with such wastewater may be considered safe for consumption. Index Terms:- cabbage, carrot, heavy metals, irrigation, lettuce, mining, wastewater ———————————————————— 1 INTRODUCTION 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 [1]. Heavy metals are often harmful to humans and other life forms, as they can cause cancer, blindness, loss organ function, severe illness, and death [2]. 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 [3], [4], [5], [6], [7]. Metals-accumulating plants are directly or indirectly responsible for much of the dietary uptake of toxic heavy metals by humans and other animals [8]. 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 [9], [10]. Vegetables such as cabbage (Brassica juncea, Brassica oleracea) cultivated in wastewater-irrigated soils take up heavy metals in large enough quantities to cause potential health risks to the consumers [11]. Brassica juncea was chosen as a model plant for rhizofiltration because it accumulates high level of lead and other heavy metals. In addition, several members of the Brassicaceae family have been shown to accumulate unusually high concentrations of heavy metals in both shoots and roots [12]. Pollution of groundwater, soil and streams with heavy metals poses environmental problem and serious threat to human health and animals that still needs effective and affordable technological solutions [13]. Ion exchange, chemical and microbiological precipitation methods among others have been developed to remove heavy metals from water, but their use is limited because they are capital, labour and energy intensive [12]. The use of plant in environmental clean-up of such toxic metals can guarantee a greener and cleaner planet for all of us at a cheaper cost. The aim of this work was to measure the concentration of heavy metals in soil and wastewater (from Nagodi mining site) and their translocation in Lactuca sativa, Brassica oleracea L. var capitata and Daucus carrota var sativa and also to evaluate and compare the bioaccumulation of heavy metals in the vegetables grown on soil and wastewater of Nagodi mining site. 2. MATERIALS AND METHODS 2.1 Pot experiment A pot experiment was conducted using surface soil (0-20cm). The pots were filled with approximately 140 kg of soil sample. The soil sample used for the treatments was taken from Nagodi mining site whilst soil from non-mining area was used as control. The pots filled with polluted soil were irrigated with wastewater from the mining site until the plants matured. Also, the pots with control soil samples were irrigated with tap water of known heavy metal concentration. Lactuca sativa and Brassica oleracea L. var capitata seeds were nursed three weeks before being transplanted into various pots. Daucus carrota var sativa however, was sown at stake. _______________________________ G. A. Boamponsem is a lecturer at University for Development Studies, Biotechnology Department, Faculty of Agriculture, Nyankpala Campus, Tamale- Ghana. Email: gaddae@uds.edu.gh Debrah is a Teaching Assistant at University for Development Studies, Biotechnology Department, Faculty of Agriculture, Nyankpala, and Tamale-Ghana. Email: isaiah20009@gmail.com M. Kumi is a Research Scientist at Water Research Institute, Council for Scientific and Industrial Research, Tamale – Ghana. Emial: michaelkumi@yahoo.com