Table 4 Correlation matrix among the different trace metals in sediment from Akaki River catchment and Aba Samuel reservoir in dry and rainy seasons

Dry season

 Cd

1

 Cr

− 0.75*

1

 Cu

0.22

0.04

1

 Fe

− 0.21

0.39

0.04

1

 Pb

− 0.72*

0.85*

0.11

0.01

1

 Mn

− 0.72*

0.81*

− 0.12

0.73*

0.60*

1

 Ni

− 0.71*

0.97*

0.13

0.43

0.85*

0.83*

1

 Zn

0.38

0.15

0.59

0.06

0.15

− 0.15

0.17

1

Rainy season

 Cd

1

 Cr

0.28

1

 Cu

− 0.09*

− 0.08

1

 Fe

0.75*

0.67*

0.02

1

 Pb

− 0.57

− 0.19

0.03

− 0.78*

1

 Mn

0.66*

0.66*

0.02

0.99*

− 0.82*

1

 Ni

0.52

0.81*

0.12

0.61*

− 0.06

0.55

1

 Zn

− 0.15

0.26

0.46

0.17

− 0.05

0.17

0.28

1