Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 5(2), 8-10, February (2015) Res. J. Chem. Sci. International Science Congress Association 8 Determination of some Heavy Metals in Soil Sample from Illela Garage in Sokoto State, Nigeria Yusuf A.J., Galadima A., Garba, Z.N. and Nasir I.1 Department of Pharmaceutical and Medicinal Chemistry, Usmanu Danfodiyo University, Sokoto, NIGERIA Department of Pure and Applied Chemistry, Usmanu Danfodiyo University, Sokoto, NIGERIAAvailable online at: www.isca.in, www.isca.me Received 14th December 2014, revised 24th January 2015, accepted 14th February 2015 AbstractThe research investigated the concentration of some heavy metals in soil sample from Illela garage in Sokoto state using Atomic Absorption Spectroscopy (AAS). The results obtained for these metals (Fe, Cr, Cd, Zn and Pb) from the sample location indicated that Fe was higher than all other metals. The results obtained in dry weight were Fe (1771.00 ±112.73 µg/g), Pb (117.30±7.13 µg/g), Cr (51.75±2.93µg/g), Zn (30.54±0.61 µg/g) and Cd (0.277±0.02 µg/g). The soil pH in waters was 7.12 and in CaCl2 was 6.39 and the moisture content was 5%. The concentration obtained was generally higher than the tolerable limit for safe environment as prescribed by Nigerian Federal Environmental Protection Agency (FEPA) and World Health Organization (WHO). Keywords: Heavy metals, soil, atomic absorption spectroscopy.Introduction Pollution in recent years has increased considerably as a result of increasing human activities such as burning of fossil fuels, industrial and automobile exhaust emissions which were identified as primary sources of atmospheric metallic burden1,2 and was well established that a variety of motor vehicles introduced a number of toxic metals into the environment. Several studies have shown that metals such as Pb, Fe, Cd, Cr, Mn, Co amongst others are responsible for certain diseases that have lethal effects on man, animals and plant. According to WHO, 20 million children worldwide suffer from pollution which has become critical. The most common environmental pollutants in the world are heavy metals. The knowledge of heavy metals accumulation in soils, the origin as well as possible interactions of these metals is a problem of concern. As human activities began to undergo industrialization, the amount of waste thrown in the environment increased tremendously. Heavy metals can accumulate in the soils to toxic levels as a result of untreated waste waters and fertilizer. The extent of soil pollution by heavy metals is very alarming because of their toxicity which lead to adverse effects on human and ecosystem health. Chronic exposure to heavy metals leads to serious kidney malfunction, anaemia, hematological and brain damage10. Therefore, it is important to monitor some of the heavy metals pollutants in soil as such this research is aimed at evaluating the level of metallic element concentrations in soil which followed laid down procedures. The paper reports a spectroscopic investigation of heavy metals in soil samples from a garage (i.e. Illela garage, Sokoto) where automobile repairs are prominent. The study examines the potential environmental risk of these activities in the area. Material and Methods Sample Collection: The sampling was carried out in the month of June, 2009 and the sampling site was at Illela garage of Sokoto state. The sample was collected from the sample location using clean stainless steel material. The soil sample was collected at 15cm depth around the sample area; it was thoroughly mixed and transferred into clean and labeled polythene bag for onward analysis in the laboratory. Sample Treatment: The soil sample was oven dried at 105C to constant weight for 6 hours11. The oven dried material was crushed and sieved through 2.00mm mesh to obtain a representative sample. Soil pH: The soil pH was determined in1:1 soil water suspension and 1:2 soil 0.01M calcium chloride suspension as described in manual12. 20g of air dried soil sample was weighed into a 50cm beaker and mixed with 200cm of distilled water and 0.01M CaCl separately. The mixture for each was stirred for 30minutes and allowed to stand for 1 hour. The pH reading was taken after inserting the electrode of the pH meter into the partly settled suspension and reported the result as soil pH in water and 0.01M CaCl. The pH meter was calibrated with 7.0 distilled water and pH buffer solution before used. The electrode was washed and wiped with dry clean filter paper after each reading11. Moisture Content Determination: The soil sample was dried at a temperature of 105C for 24hours and dried to constant weight. The sample was removed and cooled in a desiccator and Research Journal of Chemical Sciences ___________________________________________________________ ISSN 2231-606XVol. 5(2), 8-10, February (2015) Res. J. Chem. Sci. International Science Congress Association 9 weighed again. The weight lost was obtained by subtracting the weight of dry sample from original weight of the sample using the following equation12; Loss in weight on drying (g) Moisture content (%) = × 100 Initial weight of sample Sample Digestion: 1g of the oven dried sample ground sample was weighed using a top loading balance and placed in a 250ml beaker which has been previously washed with nitric acid and distilled water. The sample was reacted with sample was reacted with 5ml of HNO, 15ml of concentrated HSO4 and 0.3ml of HClO using dropping pipette. The mixture was digested in a fume cupboard, heating continued until a dense white fume appeared which was then ingested for 15minutes, set aside to cool and diluted with distilled water. The mixture was filtered through acid washed Whattman No.44 filter paper into a 50ml volumetric flask and diluted to mark volume7,13,14. The sample solution was then aspirated into the Atomic Absorption Spectroscopic machine at intervals. Results and Discussion The results of pH, moisture content determination and average concentration of heavy metals in soil sample collected at Illela garage are presented in tables-1, 2 and 3 respectively; Table-1 pH of Soil sample Source pH in Soil pH in 0.01M CaCl 2 Illela garage, Sokoto 7.12 6.39 Table-2 Moisture content of Soil sample Source Moisture (%) Illela garage, Sokoto 5.00 Table-3: Heavy metal distribution in Illela garage, Sokoto (µg/g dry weight) S/No Element Mean±SD 1 Zn 30.54±0.61 2 Pb 117.3±7.13 3 Cr 51.75±2.93 4 Fe 1771±112.73 5 Cu 0.277±0.02 Values are expressed as mean ± standard deviation of replicate determinations. The pH of the soil is an important parameter that directly influences mineral mobility. The soil pH of the sampling site in water is 7.12 indicating neutrality (table-1). The soil pH in CaCl is 6.39 indicating moderately acidic soil. In general, the acidic nature of the soil may be attributed to the industrial pollution of acidic gases, effect of bush burning and harmattan dust. The higher pH of Illela garage can also be attributed to the deposition of calcium compounds in the soil of Sokoto state. Brady and Weil15 reported that, the neutral to alkaline pH observed in semi-arid soil such as that of Sokoto was due to low rainfall, alkaline compounds are not leach away, thus making the soil of the region too alkaline. The moisture content of the sampling site was 5.0% (table-2) which might depend on the nature of the soil. The results of the study revealed that Fe, Pb, and Cr present in the soil sample are in higher concentrations than Zn and Cd, that are in trace amount and were in the following order of abundance Fe � Pb� Cr� Zn� Cd (Table 3). Fe is present in concentration higher than other metals investigated because of geographicalorigin of the soil16. Pb was high due towide use of lead products in storage batteries and its anthropogenic sources being the combustion of leaded gasoline17. The higher Fe, Pb and Cr concentrations showed that there is heavy metals pollution at the sampling site where anthropogenic activities such as battery charging, welding are heavier while the lower concentration of Zn and Cd showed that anthropogenic activities are lower and could be as a result of variety of iron salt17,18. In general, the results obtained showed that, the heavy metals concentration in the soil sample can be attributed to leaching of the top soil and unproductive nature of the garage at the time of sampling. The distribution pattern of the metals in the soil sample were similar to those reported by many researchers18-21. The concentrations of Fe, Pb and Cr have exceeded the permissible limit prescribed by World Health Organization WHO22 and Federal Environmental Protection Agency23. This means that the inhabitants of this area are vulnerable to heavy metal toxicity24,25. Conclusion The concentrations level of heavy metals determined in the present study are generally higher than the tolerable limits prescribed by WHO and FEPA, implying that the inhabitants around the sampling site are liable to heavy metal pollution. References 1.Arbike D.S., Environmental Impact of Nigerian Society of Chemical Engineers, November, 14-16 (1996) 2.Begum A., Ramaiah M. Harikrishna, Khan, I. and Veena K., Heavy metal pollution and chemical profile of Cauvery River water, E-J. of Chem., 6, 47-52 (2009)3.Williamson S., Fundamentals of air pollution reading, measurement. 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