BRASILIA, Feb 4 (Reuters) - Brazil sank a decommissioned aircraft carrier in the Atlantic Ocean off its northeast coast, the Brazilian Navy said, despite warnings from environmentalists that the rusting 1960s French-built ship would pollute the sea and the marine food chain. Brazil's Navy said it asked the company to repair the carrier at a Brazilian shipyard, but after an inspection showed it to be taking on water and was at risk of sinking, the Navy banned the ship from entering Brazilian ports. See here for a complete list of exchanges and delays