Revelation 8:8

8:8 Then the second angel blew his trumpet, and something like a great mountain of burning fire was thrown into the sea. A third of the sea became blood,

Revelation 9:15

9:15 Then the four angels who had been prepared for this hour, day, month, and year were set free to kill a third of humanity.

Revelation 16:4

16:4 Then the third angel poured out his bowl on the rivers and the springs of water, and they turned into blood.