n.脫氮作用；反硝化作用
In a process called denitrification, the microbes convert nitrates in the water into nitrogen gas, which is released into the atmosphere. 在這種名為脫氮作用的過程中，微生物將在水中的硝酸鹽肥料轉化為氮氣，并釋放進入大氣環(huán)境。
