4 billion for mercury.
( ( ( 4 billion ) ( for mercury ) ) . )
(ROOT (NP (NP (QP (CD 4) (CD billion))) (PP (IN for) (NP (NN mercury))) (. .)))
Cleaning up mercury pollution costs billions of dollars every year.
( ( ( Cleaning up ) ( mercury pollution ) ) ( ( costs ( billions ( of ( dollars ( every year ) ) ) ) ) . ) )
(ROOT (S (S (VP (VBG Cleaning) (PRT (RP up)) (NP (NN mercury) (NN pollution)))) (VP (VBZ costs) (NP (NP (NNS billions)) (PP (IN of) (NP (NP (NNS dollars)) (NP (DT every) (NN year)))))) (. .)))