RESEARCH ART I CLE DETERMI NATI ON OF HEAVY METALS I N SOME SELECTED WASTE DUMPSI TES I N GBOKO METROPOLI S, BENUE STATE, NI GERI A Anhwange Benjamin, Kaana Asemave, Leke L., and Igbum O.G Department of Chemistry, Benue State University P. M. B.102119 Makurdi, Nigeria ARTI CLE I NFO ABSTRACT Heavy metals were determined from waste dumpsites in Gboko metropolis, Benue state, Nigeria. The mean pH values of the soil samples were found to be 7.70 and 7.15 for Gboko North and South respectively. The analysis of heavy metals indicate that samples from Gboko North show mean concentrations (mg/kg) of heavy metals as; Pb (0.966), Ni (0.514), Cd (0.298), Al (0.223), Cr (0.092), As (0.051). Samples from Gboko South indicate mean levels of heavy metals as follows; (1.300mg/kg), (0.377 mg/kg), (0.191mg/kg), (0.009mg/kg), (0.18mg/kg), (0.042mg /kg) for Pb, Al, Cr, Ni, As, and Cd respectively. In Nutshell, Ni, and Cd were found to be relatively higher in Gboko north than Gboko south. On the other hand, the levels of Pb, Cr, Al, and As were higher in Gboko South than Gboko North. All the heavy Metals were within the WHO acceptable limits except Cd and Cr which were slightly above these limits in some dumpsites. Although Heavy metal concentration in refuse dumpsites of Gboko metropolis may not appear to pose a very serious environmental problem at the moment, continuous accumulation of these metals in Gboko metropolis may result into some health threat to human and the environment in future. Copy Right, IJCR, 2012, Academic Journals. All rights reserved. INTRODUCTION Like many cities among developing country, Gboko, a major town in north central Nigeria is faced with environmental challenges such as improper disposal of refuse near residential areas and other public places within the town. It is very common to find huge refuse dumpsites within residential areas and along some minor and major roads. Most dumpsites in Gboko especially those located on undeveloped plots of land are used as ‘fertile soils’ for the cultivation of vegetables and other annual crops. The cultivation of these crops on these dumpsites may lead to physical and chemical interaction between the waste materials and the crops [1]. Such interactions may be short or long depending on the type of materials and their degree of exposure [2]. Leachates from refuse dumpsites may result into contamination of soil (i.e invariably the vegetation) and the aquatic environment [3]. The most common pollutants found from refuse dumps are the heavy metals. The contamination of soils and hence the vegetation by heavy metals via dumpsites means has being a major concern for all [4]. High and excessive accumulation of heavy metals in soil may eventually contaminate the food chain [5]. Studies have shown that municipal refuse may increase heavy metal concentration in soil and underground water which may have effects on the host soils, crops and biodiversity. Total heavy metal content is a critical measure in assessing risk of a refuse dumpsite [1]. Predicting the impact of the emission of heavy metal on the environment requires *Corresponding author: kasemave@gmail.com the evaluation of not only the short-term fate of the pollutants, but also of their medium-and long-term interaction with the ecosystem. The information obtained can be used to establish risk assessment criteria and to design remediation strategies [6]. This study is therefore target to investigate the level of some heavy metals (lead Pb, nickel Ni, cadmium Cd, aluminum Al and chromium Cr) in soils from refuse dumpsites found within Gboko municipal area of Benue state, central Nigeria. MATERIALS AND METHODS Sample collection and preparation Soil samples of topsoil (0-12cm) were collected in triplicate from three dumpsites in each of the two zones of Gboko metropolis (Gboko North and South). Composite samples were made out of them in a polyethylene bag and taken to the laboratory for analysis. The samples were air dried, ground to pass through a 2mm sieve using mortar and pestle. Digestion of samples 0.5g of the sieved soil sample was digested in 12ml of aqua regia (3:1 HCl-HNO 3 v/v) using a hotplate in a fume cupboard at until white fumes were observed. The sample was allowed to cool to room temperature and then diluted with 20ml of 2% nitric acid (v/v). The mixture was transferred into a 100ml volumetric flask after filtering using whatman no.42 filter I SSN: 0975 -833X Available online at http://www.journalcra.com International Journal of Current Research Vol. 4, Issue, 11, pp.278-280, November, 2012 I NTERNATI ONAL JOURNAL OF CURRENT RESEARCH Article History: Received 15 th August, 2012 Received in revised form 19 th September, 2012 Accepted 24 th October, 2012 Published online 30 th November, 2012 Key words: Concentration, Dumpsites, Heavy Metals, Soil samples.