依靠自身运动来达到净化。一般指自然界通过自身固有的物理、化学、生物作用来减少环境污染to self-purify

• 水中污染物会随海流冲刷而得到自净。

  Water pollutants will self-purify as they are buffeted by ocean currents.

• 干旱少雨的自然环境使河流自净能力大为降低。

  An arid natural environment with little rain drastically reduces a river's self-purification capability.