Respuesta :

Assuming this is for AP Environmental Science.

There’s the nitrogen cycle that circulates nitrogen around the globe. However, human activities can affect it and add nitrogen into the atmosphere such as deforestation. Plants use nitrogen in order to thrive. If humans cut it down, the nitrogen inside it will come out. Natural forces such as light night can also create nitrogen.

Answer:

I would have to say sewage treatment plants, inorganic nitrogen fertilizers, and pollution from factories.

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