Mountain security troopers have a tough job as they have to stay in the mountains all year round.
こんにちは。
Mountain security troopers have a tough job as they have to stay in the mountains all year round.
山岳警備隊員は一年中山に常駐しなければいけないので、大変な仕事です。
「一年中」は all year round と言えます。他に all year long、year-round、throughout the year とも言います。
ぜひ参考にしてください。