甲烷的排放，除了来自大自然，如海洋、永冻层和一些湿地外，也来自人为的污染。

Methane emissions are produced from natural sources such as oceans, permafrost, some wetlands, and also from human-made sources.

youdao

砷污染越来越成为一个严重的环境问题和社会问题，目前最为严重的正是人为的污染。

Arsenic pollution is becoming an more and more serious environmental and social problem. Now man-made pollution is the most severe.

youdao

鲸鱼正处于危险之中，因为有些人污染了它们的海洋家园，还有些人为了吃肉而进行捕杀。

Whales are in danger because some people make their ocean home dirty and others kill them for meat.

youdao