0) 



(D 

 Q. 



0.020 -n 



0.016 



CD 



0.012 — 



c 

 g 



i_ 



o 



c 



o 



.O 



0.008 — 



0.004 — 



0.000 



As 



Pb 



B 



Ni 



Cd 



Se Cr 



Zn Cu 



