|   K  |       As  |       Pb  |       Cd  |       Cr  |       Cu  |       Zn  |       Hg  |    
|   Lower  |       −0.839  |       +0.637  |       −0.544  |       +0.839  |       −0.454  |       −0.999*  |       −0.839  |    
|   Lower middle  |       −0.018  |       +0.5  |       −0.866  |       +0.356  |       −0.866  |       −0.075  |       +0.866  |    
|   Middle  |       −0.811  |       −0.772  |       −0.370  |       −0.820  |       +0.5  |       −0.757  |       −1*  |    
|   High  |       −0.994*  |       −0.993*  |       +0.356  |       +0.300  |       −0.851  |       0.962  |       −0.999*  |