Bioavailability Studies of Metals in Surface Water of River Challawa, Nigeria

Table 1

Mean (±SD) of total metal concentrations in surface water of River Challawa (mgL⁻¹).

	A	B	C	D	E	F
	Warm and dry season
Zn	0.44 ± 0.01	0.15 ± 0.00	0.14 ± 0.01	0.67 ± 0.01	0.31 ± 0.01	0.97 ± 0.01
Pb	2.05 ± 0.07	9.05 ± 0.07	3.05 ± 0.07	4.34 ± 0.01	5.00 ± 0.00	9.00 ± 0.00
Cu	0.35 ± 0.07	0.51 ± 0.01	0.41 ± 0.01	0.10 ± 0.00	0.09 ± 0.01	0.00 ± 0.00
Cr	12.51 ± 0.01	6.68 ± 0.01	11.68 ± 0.01	11.68 ± 0.01	0.00 ± 0.00	0.00 ± 0.00
Cd	0.11 ± 0.01	0.22 ± 0.00	0.16 ± 0.01	0.16 ± 0.01	0.16 ± 0.01	0.11 ± 0.01
	Cool and dry season
Zn	2.05 ± 0.01	3.12 ± 0.01	2.26 ± 0.01	0.88 ± 0.01	2.69 ± 0.01	1.64 ± 0.01
Pb	2.63 ± 0.01	2.05 ± 0.07	2.15 ± 0.07	2.35 ± 0.07	2.20 ± 0.00	3.05 ± 0.07
Cu	0.21 ± 0.01	0.14 ± 0.01	0.15 ± 0.01	0.07 ± 0.01	0.08 ± 0.00	0.00 ± 0.00
Cr	3.10 ± 0.14	4.25 ± 0.01	3.30 ± 0.14	4.59 ± 0.02	2.47 ± 0.00	0.10 ± 0.00
Cd	0.47 ± 0.01	0.40 ± 0.00	0.71 ± 0.01	0.24 ± 0.00	0.30 ± 0.00	0.08 ± 0.00
	Hot and dry season
Zn	1.08 ± 0.01	0.90 ± 0.00	1.99 ± 0.01	0.92 ± 0.01	3.86 ± 0.01	1.83 ± 0.01
Pb	3.45 ± 0.07	4.07 ± 0.01	2.51 ± 0.01	2.16 ± 0.01	2.15 ± 0.07	3.36 ± 0.01
Cu	0.01 ± 0.00	0.01 ± 0.00	0.01 ± 0.01	0.31 ± 0.01	0.04 ± 0.01	0.00 ± 0.00
Cr	3.15 ± 0.07	3.20 ± 0.00	3.10 ± 0.14	6.00 ± 0.00	0.55 ± 0.07	0.00 ± 0.00
Cd	0.62 ± 0.00	0.15 ± 0.01	0.58 ± 0.01	0.19 ± 0.01	0.14 ± 0.01	0.06 ± 0.01
	Warm and wet season
Zn	1.71 ± 0.01	1.30 ± 0.00	3.01 ± 0.01	1.56 ± 0.01	1.75 ± 0.01	2.85 ± 0.07
Pb	1.43 ± 0.01	2.60 ± 0.00	2.15 ± 0.07	2.25 ± 0.01	1.10 ± 0.00	1.25 ± 0.07
Cu	0.02 ± 0.00	0.01 ± 0.00	0.01 ± 0.00	0.02 ± 0.00	0.01 ± 0.00	0.00 ± 0.00
Cr	3.75 ± 0.07	4.05 ± 0.07	4.25 ± 0.07	7.10 ± 0.14	0.61 ± 0.01	0.31 ± 0.01
Cd	0.10 ± 0.01	0.07 ± 0.01	0.06 ± 0.01	0.14 ± 0.01	0.09 ± 0.01	0.00 ± 0.00
Standard limit		Pb	Cr	Cu	Zn	Cd
WHO		0.1	0.1	—	—	0.01
EPA		0.05	0.1	1.3	5	0.01
FEPA		<1	0.05	<1	<1	<1

WHO [19], FEPA [20], and EPA [21].