natural pollution source

As a source of cleaner energy, the natural gas is able to reduce the air pollution by burning coal.

天然气作为一种清洁能源，能够减少燃煤造成的大气污染。

The natural degradation speed of the pollution of chemical pollutants in the soil is very slow under a natural condition, so a long-time pollution source to underground water is formed.

土壤中的化学污染物在自然条件下污染自然降解速度非常缓慢，形成对地下水的长期污染源。

Objective: to understand the pollution of the Yellow River in HuiNong of NingXia Autonomous Prefecture and in natural water source and running water quality.

前言：目的：掌握黄河水源宁夏惠农段污染现状和目前自来水水质现状。