Sense weakness in turn bets, how're these river bluffs?? (50 NL)

Did this to the same opponent about 15 minutes apart. He is weak-tight.

Hand #1
3 handed (50 NL)
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Hero is in SB, Villian in BB

Hero dealt A /images/graemlins/diamond.gifK /images/graemlins/heart.gif

1 fold, Hero raises to $2, Villian calls

Flop $4, 10 /images/graemlins/diamond.gif9 /images/graemlins/spade.gif3 /images/graemlins/club.gif

Hero bets $2.50, Villian calls $2.50

Turn $9 4 /images/graemlins/spade.gif

Hero checks, Villian bets $.50, Hero calls $.50

River $10 3 /images/graemlins/spade.gif

Hero bets $8
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Hand #2
same game 4 handed
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Hero is in SB with A /images/graemlins/diamond.gifQ /images/graemlins/diamond.gif, Villian in seat 3.

2 calls. Hero raises to $2.50, BB folds, Villian calls $2.50

Flop $6.50, 7 /images/graemlins/diamond.gif6 /images/graemlins/club.gif5 /images/graemlins/spade.gif

Hero bets $4, Villian calls $4

Turn $14.50, 3 /images/graemlins/diamond.gif

Hero checks, Villian bets $3.50, Hero calls $3.50

River $21.50, 7 /images/graemlins/heart.gif

Hero bets $15