Download Eutrophication

Eutrophication
By Oli Murphy
A Team Pickles Production
A Definition
•
Eutrophication is a process whereby water bodies, such as lakes, estuaries, or slowmoving streams receive excess nutrients that stimulate excessive plant growth
(algae, periphyton attached algae, and nuisance plants weeds). This enhanced plant
growth, often called an algal bloom, reduces dissolved oxygen in the water when
dead plant material decomposes and can cause other organisms to die. Nutrients
can come from many sources, such as fertilizers applied to agricultural fields, golf
courses, and suburban lawns; deposition of nitrogen from the atmosphere; erosion
of soil containing nutrients; and sewage treatment plant discharges. Water with a
low concentration of dissolved oxygen is called hypoxic.
Why it happens
Eutrophication is caused by a runoff of
fertiliser which increases the nutrients
in the waterways that in turn increases
the fertility. This means there is greater
competition and a large amount of
plants die. Bacteria use the dead matter
in respiration, absorbing oxygen from
the water so that other organisms in
the water cannot respire
Here is an example of an experiment in a
Lake in which on one side of the boom
fertiliser has been added whilst the other
side has been left natural
How it can be overcome
The most important thing is to use organic fertilisers. These
break down a lot slower and so not all the nutrients are
released at once reducing the plant bloom
Spraying fertilisers at appropriate times of year is also
important when it is not likely to washed off by rain into
water ways
Fertilisers should not be sprayed around streams rivers and
lakes so that they do not become contaminated.