我们需要降低水中的硝酸盐含量。
High levels of nitrate occur in the Midwest because of the heavy use of fertilizers.因为大量使用化肥,中西部地区的硝酸盐含量很高。
Even nitrogen, which is a gas in its elemental state, is normally absorbed from the soil as nitrate ions.即使是元素状态为气体的氮,也通常作为硝酸根离子从土壤中被吸收。