Eutrophication and acid mine drainage are two of the most important water
quality problems in South Africa. Write a mini-essay describing what they are,
what causes them and their effects on the environment.
Eutrophication
• is the addition of high levels of nutrients especially nitrogen and phosphorus to
water.
• It is caused by allowing untreated sewage to flow into rivers or wetlands - Also
when fertilisers get washed into rivers, streams.
• or when fertiliser industries pour waste into rivers, streams
• The extra nutrients allow the algae and other aquatic plants to grow
• and reproduce very quickly and cover the surface of the water.
• The rapid growth of algae is called an algal bloom.
• Certain algae in algal blooms can release toxins into the water - that are
harmful
to humans and other animals.
• The algae become overcrowded and eventually they die
• due to a lack of sunlight.
• Bacteria in the water decompose the dead plant material.
• The bacteria use up a lot of the oxygen in the water during decomposition - As
a
result, aquatic animals e.g. fish insects etc. die
• due to a lack of oxygen.
Acid Mine Drainage (AMD)
• is the drainage of highly acidic water from mines onto the surface of the land
or
into groundwater.
• Acid mine water is formed when groundwater flows over the rocks in old mine
shafts and tunnels in gold and coal mines.
• The water dissolves sulphide minerals out of the rocks
• which form sulphuric acid.
• The sulphuric acid lowers the pH of the water.
• The sulphuric acid in turn dissolves metals out of the rocks.
• These metals include toxic heavy metals such as manganese, and radioactive
practices.
• Radium and uranium are radioactive elements which release radiation
• into the environment, which is very harmful to living organisms.
• Acid mine water gradually fills up old mines and rises to the surface
• where it spreads out and pollutes rivers and wetlands and harms or kills plants
and
animals
• that are in contact with the water
• It also moves into underground water supplies
• which may be used for irrigation or drinking and will therefore harm plants and
animals in this way too.
quality problems in South Africa. Write a mini-essay describing what they are,
what causes them and their effects on the environment.
Eutrophication
• is the addition of high levels of nutrients especially nitrogen and phosphorus to
water.
• It is caused by allowing untreated sewage to flow into rivers or wetlands - Also
when fertilisers get washed into rivers, streams.
• or when fertiliser industries pour waste into rivers, streams
• The extra nutrients allow the algae and other aquatic plants to grow
• and reproduce very quickly and cover the surface of the water.
• The rapid growth of algae is called an algal bloom.
• Certain algae in algal blooms can release toxins into the water - that are
harmful
to humans and other animals.
• The algae become overcrowded and eventually they die
• due to a lack of sunlight.
• Bacteria in the water decompose the dead plant material.
• The bacteria use up a lot of the oxygen in the water during decomposition - As
a
result, aquatic animals e.g. fish insects etc. die
• due to a lack of oxygen.
Acid Mine Drainage (AMD)
• is the drainage of highly acidic water from mines onto the surface of the land
or
into groundwater.
• Acid mine water is formed when groundwater flows over the rocks in old mine
shafts and tunnels in gold and coal mines.
• The water dissolves sulphide minerals out of the rocks
• which form sulphuric acid.
• The sulphuric acid lowers the pH of the water.
• The sulphuric acid in turn dissolves metals out of the rocks.
• These metals include toxic heavy metals such as manganese, and radioactive
practices.
• Radium and uranium are radioactive elements which release radiation
• into the environment, which is very harmful to living organisms.
• Acid mine water gradually fills up old mines and rises to the surface
• where it spreads out and pollutes rivers and wetlands and harms or kills plants
and
animals
• that are in contact with the water
• It also moves into underground water supplies
• which may be used for irrigation or drinking and will therefore harm plants and
animals in this way too.
