tide, 28, 29, 44 



toxicity, 23 



trace metals, 18, 22, 24 

 arsenic (As), 18,20 

 cadmium (Cd), 18,20,24 

 chromium (Cr), 18,20 

 copper (Cu), 18,21,24 

 lead(Pb), 18,21 

 mercury (Hg), 18,21 

 nickel (Ni), 18,21 

 vanadium (V), 5, 12,24,27 

 zinc(Zn), 12, 18,24,27 



volume 



difference, x 



waves, 28, 36 



