Barrons AP Environmental Science

(Marvins-Underground-K-12) #1

  1. (C) At the point of discharge, there is a sudden increase in the amount of
    toxins, suspended solids, and dissolved organic compounds. The water
    becomes unsuitable for any human use. Aerobic bacteria increase rapidly,
    reducing the organic pollutants but using up dissolved oxygen. As the
    oxygen level falls, anaerobic bacteria multiply, resulting in an unpleasant
    smell or stench. Eventually, as their food supply is used up, the decomposers
    reduce and algae thrive, reoxygenating the water. Fish and other animal life
    reappear, and the stream returns to its previous condition.

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