Eutrophication
Peter Fergie
What is the problem?
•Eutrophication is a process by which an excess of nitratescan kill of populations of water-based organisms.
•This is due to the build up in nitrates increasing thepopulation sizes of some plants in the water throughincreased fertility.
•When these plants die, there is an excess of organic deadmatter.
•This dead matter is then used by bacteria in aerobicrespiration, allowing the bacteria to absorb more oxygenfrom the water.
How does that affect other organisms?
•With more oxygen being absorbed by the bacteria, there isless available for larger organisms which don’t have thenecessary adaptations to cope with lower oxygen levels.
•These organisms, often fish, can then no longer respireaerobically and will therefore die.
•This affects the whole cycle exponentially, as there is nowmore dead matter, and therefore more bacteria respiringaerobically, 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 chemicalfertilizers on their land.
•These fertilizers contain large amounts of Potassium,Phosphorus and Nitrogen.
•It’s the nitrogen which causes all the problems, in the formof nitrates.
•An excess of these will be washed out from the fields bythe rain in a process called “run-off”, where the nitratesthen accumulate in nearby rivers and ponds.
•This then links back to the original slide where the waterplant population increases.
How can the problem be overcome?
•The magnitude of the problem can bedecreased by a number of factors.
•These include not overly fertilizing fields,using an organic fertilizer, and not releasingraw sewage into rivers and lakes.
•A reduction in fertilizer usage would leavethe land with less excess nitrates going towaste and causing eutrophication.