pollution type

例句：

1. 1. The pollution type of the river has been a major concern for environmentalists.
   河流的污染类型一直是环保人士关注的重点。
2. 2.The study identified several pollution types that could be mitigated through technological advancements.
   研究确定了几种可以通过技术进步来减轻的污染类型。
3. 3. The government is working on developing new regulations to control different pollution types in the city.
   政府正在制定新规定，以控制城市中不同类型的污染。