Table 1 Concentrations of Cu and Zn in the benthic sediment and two dominant gastropod species of River Osun and their accumulation factors

Mean ± s.e. (μg/g) of Cu

Contamination factor

Mean ± s.e. (μg/g) of Cu

Accumulation factor

Mean ± s.e. (μg/g) of Cu

Accumulation factor

1.16 ± 0.25

0.02

2.07 ± 0.37

1.79

3.11 ± 0.45

2.68

2.41 ± 0.76

0.05

2.11 ± 0.68

0.88

1.87 ± 0.55

0.78

1.36 ± 0.31

0.03

2.98 ± 0.34

2.19

2.67 ± 0.38

1.96

1.21 ± 0.77

0.02

2.13 ± 0.40

1.76

2.32 ± 0.31

1.92

Mean ± s.e. (μg/g) of Zn

Contamination factor

Mean ± s.e. (μg/g) of Zn

Accumulation factor

Mean ± s.e. (μg/g) of Zn

Accumulation factor

6.05 ± 0.96

0.09

8.11 ± 1.35

1.34

9.09 ± 1.37

1.50

8.96 ± 1.37

0.13

5.51 ± 0.89

0.61

9.4 ± 1.41

1.05

6.96 ± 1.03

0.10

6.84 ± 0.83

0.98

12.51 ± 0.44

1.79

3.17 ± 1.11

0.05

4.57 ± 0.81

1.44

10.56 ± 1.34

3.33