Transcript DA-E_5.3_and_E_5.4

E 5.3 and E 5.4
Dixon Adair
Eutrophication – Slide 1
• The process of excessive anaerobic
decay, which produces smelly and toxic
decay products, poisons the water and
leaves it devoid of life.
• How it happens: When nitrates and
phosphates (namely coming from
agricultural areas as runoff) accumulate in
bodies of water, they act as nutrients, and
increase the growth of plants and algae…
Eutrophication – Slide 2
• …So what?
• When these (abnormally large amounts of) algae and
plants die, they would normally decompose aerobically,
but with not enough oxygen to decompose aerobically,
they must instead decompose anaerobically. Anaerobic
decomposition is not healthy for the water, since its
products are smelly and toxic as opposed to virtually
harmless products for aerobic decomposition. As these
harmful products further poison the water, more
organisms/plants/animals die, and again, more
anaerobic decomposition must occur of the additional
dead organisms that, and so on. (Vicious Cycle)
Thermal Pollution
• The solubility of oxygen in water is temperature
dependent.
• As the temperature of the water goes up, the solubility of
oxygen in water goes down.
• To make matters worse, as the temperature of the water
goes up, the metabolic rate of fish and other organisms
increases, meaning they need more oxygen.
• In essence, the higher the water temperature, the more
oxygen the fish and organisms need, and the less they
get of it.
• So, how does it happen? Many industries use water as a
coolant, and the discharged water, which is hot (since it
was used to make other things cool and thus absorbed
the heat of the thing it was cooling) often flows into bodies
of water. This is thermal pollution.