NATALIA KORCZ EPM I
What is the eutrophication?
Addition of artificial or non-artificial
nutritious substances into water basins.
Especially biogenic elements like nitrates
and phosphates. This elements create
excessive production of algae’s biomass.
It appears as so-called ‘algal bloom’.
•are water-soluble (they dissolve
easily in water), and are commonly
applied to agricultural fields as
•are not water-soluble; they do not
usually dissolve in water. However,
they do adhere to soil particles.
Types of eutrophication
• Natural- goes very slow, from moment in
which lake starts to exist. It is caused mainly
by changes of climate. Natural eutrophication
is minimal and imperceptible for human.
• Anthropogenic –(civilization, artificial) it is
connected with public utilities; sewage,
deforestation and intensive farming.
Causes of eutrophication
• natural run-off of nutrients from the soil and the weathering
• run-off of inorganic fertilizers (containing nitrates and
• run-off of manure from farms (containing nitrates, phosphates
• run-off from erosion (following mining, construction)
• discharge of detergents (containing phosphates)
• discharge of partially treated or untreated sewage (containing
nitrates and phosphates)
Effects of eutrophication
• increase in plant and animal biomass
• increase in growth of rooted plants, e.g. reeds
• increase in cloudiness of water
• increase in rate of sedimentation
• decrease in species diversity
• change in dominant biota (e.g. carp replace trout and
blue-green algae replace normal algae) and an
• increase in the frequency of algal blooms.
• High fluactions of concentration of oxygen and pH
• Formation of anaerobic conditions
• Intensive colouring and smell
Lake Rankala, Kolhapur (India) : Eutrophic due to high
The Gulf of Mexico
Matilda Bay, Swan-Canning Estuary during February 2000
Consequences of eutrophication
• the water may become unsuitable for drinking
even after treatment
• decrease in the amenity value of the water
(e.g. it may become unsuitable for water
sports such as sailing)
• disappearance of commercially important
species (such as trout)
Chemical consequences of anoxic
When plants and algae die their remains are consumed
by aerobic bacteria. This results in a reduction of the
level of dissolved oxygen. Eventually, often near the
bottom of a lake, virtually no oxygen remains and the
water is said to be anoxic. Under these conditions
anaerobic bacteria flourish. Anaerobic bacteria often
produce foul-smelling compounds such as
– hydrogen sulphide (H2S)
– thioalcolohs (RSH) and
– ammonia (NH3).
• resulting in the water becoming extremely unpleasant
Schematic Diagram Showing effect of algal bloom
on water quality
Did you know…?
Eutrophication plagues more than half the
lakes in Europe and Asia, 41 percent of those
in South America, and 28 percent in North
• planting vegetation along streambeds to slow
erosion and absorb nutrients
• controlling application amount and of fertilizer
• directing waste water away from lakes to
rivers and the sea researching use of biological
• reducing the use of phosphates as builders in