internal pollution sources

• 内源污染

internal pollution sources的用法和样例：

例句

1. Soil erosion and non-point source pollution are two serious environmental issues.
   土壤侵蚀与非点源污染是两大重要的环境问题。
2. The distribution of non-point sources of pollution from different effluents had distinct spatial characteristics.
   各流域非点源污染的发生具有明显的地域分异特征。