11220
The effect of major cation activity ( Ca ( 2 + ) , Mg ( 2 + ) , Na ( + ) , K ( + ) ) on Ni toxicity , with dose expressed as exposure ( total dissolved Ni concentration NiTot ) or free Ni ion activity ( in solution Ni ( 2 + ) ) , or as tissue residue ( Ni concentration in plant tissue NiTiss ) to the aquatic plant Lemna minor L . was examined .
 Chemical: Ca ( 2 + ); Chemical: Mg ( 2 + ); Chemical: Na ( + ); Chemical: K ( + ); Chemical: Ni; Chemical: Ni; Chemical: Ni; Chemical: Ni ( 2 + ); Chemical: Ni
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: Ca ( 2 + ); Chemical: Mg ( 2 + ); Chemical: Na ( + ); Chemical: K ( + ); Chemical: Ni; Chemical: Ni; Chemical: Ni; Chemical: Ni ( 2 + ); Chemical: Ni