Transcript Eutrophication

Eutrophication
Peter Fergie
What is the problem?
• Eutrophication is a process by which an excess of nitrates
can kill of populations of water-based organisms.
• This is due to the build up in nitrates increasing the
population sizes of some plants in the water through
increased fertility.
• When these plants die, there is an excess of organic dead
matter.
• This dead matter is then used by bacteria in aerobic
respiration, allowing the bacteria to absorb more oxygen
from the water.
How does that affect other organisms?
• With more oxygen being absorbed by the bacteria, there is
less available for larger organisms which don’t have the
necessary adaptations to cope with lower oxygen levels.
• These organisms, often fish, can then no longer respire
aerobically and will therefore die.
• This affects the whole cycle exponentially, as there is now
more dead matter, and therefore more bacteria respiring
aerobically, causing the O2 levels to decrease further,
therefore causing more and more fish to die.
Why is this happening?
• This problem occurs when farmers use artificial chemical
fertilizers on their land.
• These fertilizers contain large amounts of Potassium,
Phosphorus and Nitrogen.
• It’s the nitrogen which causes all the problems, in the form
of nitrates.
• An excess of these will be washed out from the fields by
the rain in a process called “run-off”, where the nitrates
then accumulate in nearby rivers and ponds.
• This then links back to the original slide where the water
plant population increases.
How can the problem be overcome?
• The magnitude of the problem can be
decreased by a number of factors.
• These include not overly fertilizing fields,
using an organic fertilizer, and not releasing
raw sewage into rivers and lakes.
• A reduction in fertilizer usage would leave
the land with less excess nitrates going to
waste and causing eutrophication.