The area selected for the study are Sabo, Itagunmodi and Igun mining villages in Atakumosa West Local Government area of Osun State in Southwestern Nigeria within latitudes 7.51˚N and 7.65˚N and longitudes 4.61˚E and 4.85˚E (Figure 1) and covers an area of 577 km² and a population of 68,643 (NPC, 2006). Three mining locations each was sampled in the selected villages. The control site selected for the study is Tonkere village in Ife Central Local government area of Osun State, about 13 km from the study area.

One hundred and eight (108) samples of each soil and plantain leaves were collected from Sabo (SB), Itagunmodi (IT) and Igun (IG) gold mining villages of Atakumosa-west Local Government area of Osun State from March 2015-February 2016. One (1) kg of soil sample was collected with a hand trowel at a depth of 15cm from surface soil around the pits dug for mining. The leafy part of the plantain tree were cut, the soil and leave samples were packed differently in polythene bags sealed properly and tagged.

In the laboratory, the soil samples were air dried ground and pelletized for Particle Induced X-ray Emission (PIXE) analysis for metal concentration determination. The PIXE is a nuclear analytical technique employed in the multi-elemental determination of metals in samples. Leafy part of the plant was selected for the study. The leaves were collected and kept in labeled polythene bags; effort was made to avoid soil contamination of the samples. Samples collected were dried at 103˚C for 24 hrs, ground and sieved with a 2 mm mesh, pelletized and kept for heavy metal analysis.

Data obtained from PIXE analysis of the samples were subjected to statistical analysis using an up-to-date statistical package (SPSS V24). Descriptive and inferential analyses were equally carried out and the results compared with environmental standard limits recommended by world regulatory bodies.

The mean concentrations of eight (8) heavy metals obtained from PIXE analysis of soil and plantain leaves collected from mining locations in three villages of the

study area presented in Table 1 and Table 2. In the soil, Pb occurred mostly at Itagunmodi, between 20.65 ± 2.72 and 24.31 ± 2.88 mg/kg but was lowest at Sabo with a range of 11.05 ± 2.20 to 21.26 ± 3.30 mg/kg. The mean concentration at Igun mining site ranged between 14.42 ± 1.67 and 19.12 ± 2.39 mg/kg, Although the mean value at Itagunmodi was within the safe limit, being lower than the 100 mg/kg maximum permissible limit set for soil [16] [17] , the mean concentrations of Cd (158.50 ± 9.71 - 346.03 ± 10.12 mg/kg) and Cu (149.68 ± 2.74 - 295.63 ± 4.88 mg/kg) were greater than the recommended allowable limits of 3 mg/kg and 100 mg/kg, respectively at all the mining settlements (Table 1). Zn occurred within the safe limit at most of the sampled areas being lower than 300 mg/kg recommendation of the WHO (2008), except at Itagunmodi. Fe occurred at above normal concentrations (4016.96 ± 120.24 - 8765.45 ± 210.11 mg/kg) at all the sampling region, but the concentrations of Cr (Igun, 91.03 ± 7.91 - 121.37 ± 10.31; Itagunmodi, 68.87 ± 6.89 - 78.31 ± 3.15 and Sabo, 42.28 ± 10.62 - 47.45 ± 8.59 mg/kg) exceeded the recommended safe limits.

In the plantain leave samples, most of the investigated metals (except As, Cr and Mn) occurred in abnormally high concentrations (Pb, 3.97 ± 0.29 - 7.69 ± 0.63 mg/kg; Cd, 6.48 ± 0.58 - 22.05 ± 1.90 mg/kg, Cu, 25.13 ± 2.18 - 59.34 ± 5.21 mg/kg, Zn, 12.36 ± 1.06 - 30.34 ± 2.31 mg/kg and Fe, 48.51 ± 4.29 - 82.51 ± 7.34 mg/kg) greater than the recommended safe limit, WHO, [18] in the leaves at all the selected locations (Table 2). The Cu concentration was higher than recommended safe limit for in the plantain leaves at the control station, and also suggested the vulnerability of the non-mining site to bioaccumulation from other Cu sources. Studies showed that Cu sources include the use of CuSO₄ as herbicide in farmlands.

The lower concentrations of these metals recorded at the control sites for all the metals in both soil and plantain leave samples implicated the mining activities as sources of these metals. Heavy metals have been reported to be present in parent materials (such as rock, and minerals) in particularly high concentrations

MAL: Maximum Allowable Limit (WHO, 2004).

NMC (Normal Metal Concentration), [19] .

[19] and will be released into the environment by anthropogenic activities such as mining. High value of heavy metal, particularly Cu, Fe and Zn found in the soil samples compares well with those reported in Bagana mining area, Zamfara state, Nigeria [20] . Similar study carried out in one of the studied areas also reported heavy pollution with these heavy metals [21] . Cu is known to be particularly adsorbed by soil and plant [22] while the high Fe content in the soil samples can be attributed to the high percentage of the metal in the earth crust. The required low organic matter mineralization for effective plant growth will be disturbed as a result of negative effects of high concentrations of heavy metals on microbial activities in the soil and this is undesirable. The high concentration of these metals recorded in plantain leaves is also a confirmation of their accumulation by plants. High values of heavy metals recorded in this study for plantain leaves did not however compare well with those reported for plant materials in a neighbouring mining site in the same local Government area [23] ; this might not be unconnected with the relatively low rate of artisanal mining compared to the study site.

The results of the analysis of variance that was used to investigate spatial variations in the heavy metal concentrations across the selected locations indicate significant variations in soils (Table 3) and plantain leaves (Table 4). Except for Fe which indicated a non-significant difference between Igun and Itagunmodi on one hand and between Igun and Sabo on the other hand, As (between Sabo and the control), Zn (between Igun and the control) and Cu (between Igun and Sabo), the overall variance showed significant differences in the heavy metal concentrations in soils at the locations.

Figure 2 and Figure 3 shows the monthly distributions of selected variables in soils and plantain leaves. The metals generally occurred in higher concentrations in the dry months (November - March) than the wet months (April-July), probably due to the influence of rainfall that may be linked with a wash-off or dilution effects. Lower values of the metals observed in samples from control sites is an indication of contribution of mining activities to the heavy metal level in the study areas since other anthropogenic sources that might be responsible for the presence of high values of these metals such as presence of waste dump sites [24] , leaching from incineration points, discharge from industries, leaching from smelting and fabrication [25] etc. are obviously absent in the areas. The

study concluded that high concentrations of the metals resulted from excessive digging for the gold metal which brings the core of the soil, and increases their concentrations.