Global Journal of Science Frontier Research, H: Environment & Earth Science, Volume 21 Issue 6

Table 1: Mean concentrations of the heavy metals in the mine, mill tailing and control sites with WHO recommended limits and its toxic response factor Element Control site Mine site Mill tailing site Toxic response factor WHO recommended limits Pb 21.40 429.76 846.87 5.00 100.00 Fe 1331.45 1707.63 1914.99 N/A N/A Mn 68.10 181.61 177.70 N/A N/A Cu 35.72 90.95 739.33 5.00 30.00 Zn 11.91 37.41 100.41 1.00 300.00 As 5.73 17.99 43.52 10.00 N/A Cr 47.85 93.19 163.28 2.00 100.00 Co 18.17 47.94 53.48 N/A N/A Ni 14.26 22.28 45.59 5.00 80.00 Cd 0.23 3.23 5.83 30.00 3.00 It can be observed from the mean concentrations calculated that the mean concentrations in the mill tailing site were higher than that in the mine site and control area for all of the observed heavy metals in the study area. The Highest concentration corresponds to Fe and the lowest corresponds to Cd. The increasing trend was in the order: Cd <As <Ni <Zn <Co <Cu <Cr <Mn<Pb<Fe. The concentrations of all the observed heavy metals in the mill tailing site were found to be higher than that obtained in the mine site and control area with greater variation in relative abundance of most of the heavy metals. These variations can be attributed to the variable dumping of the mill tailing deposits. Comparing the results obtained from this study with the World Health Organization guideline on the maximum limits of toxic metals in the soils. Most of the observed heavy metals in the mine site and mill tailing site were observed to have concentrations above the WHO limit, while in the control area the concentrations were below the WHO limit. In the mine site, Pb was observed to have concentration 4 times higher than the recommended WHO limit, Co, was observed to have concentration 2 times higher than the recommended WHO limit, and Cd, was observed to have concentration 1.1 times higher than the recommended WHO limit while in the mill tailing site, Pb was observed to have concentration 8 times higher than the recommended WHO limit, Co, Cd, Ni and Cr were found to have concentrations about 2 times higher than the recommended WHO limit. b) Contamination Factor (CF) The contamination factor was used to assess the level of contamination of each element in the studied soils, based on the categories discussed in section 2.3.1, the elemental concentrations could be categorized as follows: in the mine site (i) Pb (14.94) and Cd (13.96) in the very high contamination category (ii) As (3.14) and Zn (3.14) in the considerable contamination category (iii) Mn (2.67), Cu (2.55), Co (2.64), Ni (1.56), Fe (1.28) and Cr (1.95) in the moderate contamination category and for the mill tailing site (i) Pb (39.58), Cu (20.70), Zn (8.43), As (7.61), and Cd (25.17) in the very high contamination category (ii) Cr (3.41) and Ni (3.20) in the considerable contamination category (iii) Fe (1.44), Mn (2.61), and Co (2.94) in the moderate contamination category. c) Degree of Contamination (DC) and Pollution Load Index (PLI) The degree of contamination and pollution index was used to assess the overall pollution level of the site resulting from the observed heavy metals. The pollution load index results indicate that the mine site was contaminated with all the observed heavy metals (mean PLI=2.71) and also the pollution load index results indicate that the mill tailing site was contaminated with all the observed heavy metals (mean PLI=5.78). The results of the degree of contamination index indicated that the mine site is in a very high degree of contamination (Mean DC=47.84) and also (Mean DC=115.088) for the mill tailing site respectively as described in sections 2.3.2 and 2.3.3. IV. C onclusion Determination of heavy metal pollution of soil and mill tailing samples from the AngwanKawo has been carried out using contamination factor, pollution load index and degree of contamination index. Flame Atomic Absorption Spectrometry (FAAS) were used to obtain their concentrations. The study area was observed to be contaminated with Pb, Fe, Mn, Cu, Zn, As, Cr, Co, Ni, and Cd. These heavy metals have been proved to be toxic to human health. Owing to their possible bioaccumulation, it is advisable that these sites should be subject to mandatory monitoring. Based on the findings of this study, the obtained result showed that the mine and mill tailing sites are seriously accumulated with heavy toxic metals, some of which were found to have high concentration above the WHO worldwide threshold limit. These heavy metals are thus terribly alarming and can cause serious environmental Determination of Heavy Metal Pollution in Soil Samples from Angwan Kawo Gold Mining Sites, Niger State, Nigeria 1 Global Journal of Science Frontier Research Volume XXI Issue VI Year 2021 73 ( H ) © 2021 Global Journals Version I