As chemical pollutants break down and sink into the earth, rivers become cleaner.

随着化学污染物分解并沉入地下，河流变得更加清洁。

Research has shown that chemical pollutants released into the atmosphere shrink the ozone layer over time.

研究表明，随着时间的推移，释放到大气中的化学污染物会使臭氧层缩小。

There are chemical pollutants in these waters, and they are running low on the salmon that they really rely on for food.

这些水域中存在化学污染物，它们真正赖以为生的鲑鱼也快要吃光了。