Concentrations of heavy metals (mg/l) in groundwater and soil of residential area around AWL, Ibadan, Southwest-Nigeria.

Table 3: Concentrations of heavy metals (mg/l) in groundwater and soil of residential area around AWL, Ibadan, Southwest-Nigeria.

Heavy metals (mg/l)	Awotan Landfill				Background			WHO limit
	Groundwater		Soil		Groundwater Soil			Groundwater Soil
	1-150 m (GWa)	151-300 m (GWb)	1-150 m (Sa)	151-300 m (Sb)
Pb	0.05 ± 0.01^cd(ii)	0.03 ± 0.01^a(i)	0.66 ± 0.04^d(iv)	0.61 ± 0.03^d(iii)		0.02 ± 0.02	0.45 ± 0.02	0.010	100
Cd	0.04 ± 0.01^bc(ii)	0.02 ± 0.00^a(i)	0.43 ± 0.02^c(iv)	0.32 ± 0.02^b(iii)		0.002 ± 0.01	0.29 ± 0.01	0.003	3
Cr	0.02 ± 0.01^a(i)	nd	0.37 ± 0.03^b(iii)	0.22 ± 0.01^a(ii)		0.01 ± 0.00	0.13 ± 0.01	0.050	100
Ni	0.03 ± 0.02^ab(i)	0.02 ± 0.01^a(i)	0.29 ± 0.02^a(iii)	0.16 ± 0.04^a(ii)		0.02 ± 0.01	0.17 ± 0.00	0.070	50
Cu	0.05 ± 0.03^cd(ii)	0.02 ± 0.01^a(i)	0.89 ± 0.04^f(iv)	0.54 ± 0.03^c(iii)		0.03 ± 0.01	0.21 ± 0.01	2.000	100
Fe	0.06 ± 0.01^d(i)	0.03 ± 0.02^a(i)	0.78 ± 0.04^e(ii)	0.70 ± 0.03^e(ii)		0.03 ± 0.02	0.51 ± 0.03	na	na
Zn	0.08 ± 0.04^e(i)	0.09 ± 0.03^b(i)	1.05 ± 0.06^g(ii)	1.16 ± 0.04^f(iii)		0.03 ± 0.02	0.64 ± 0.04	na	300

*means on each column and on each row having the same alphabet and Roman numeral respectively are not significantly different (p > 0.05). nd = not detected; na-not available.