effluent from discharge of sewage works and farms. Main pollutants are a.
often a limiting factor, vital for plant growth. Highly soluble and leached
from the soil. Sources – sewage /
manure / inorganic fertiliser. b.
Often limit plant growth. Fairly
insoluble. Main source – detergents in
competition the plants die. This
increases the detritus which will be
decomposed by decomposing bacteria in
the water. Increases BOD ( biochemical oxygen demand) due to
will die eg. Trout, mayfly nymph. This
leaves only animals that can cope in
conditions with little oxygen eg sludge worms and bloodworms ( indicator
highly toxic, act as enzyme inhibitors also
dioxide From combustion of
fossil fuels. Combines with water to
direction , amount of rainfall and type of soil. Affect on organisms :- a.
Increased solubility of aluminium ions from soil
results in increased mucus in fish gills and reduced haemoglobin efficiency b.
Increased acidity reduces activity of decomposers reducing availability of phosphates and
nitrates leading to oligotrophic
of individuals. c.
Reduced calcium ions results in reduced mollusc nos (
calcium needed for shells ). d.
Effect on enzymes needed for dissolving fish egg coats
leads to reduced fish. e.
disease. Lichens -are indicator species.
Crude oil From oil spills, washing tanks and
Reduced light penetration – reduced photosynthesis. ·
Reduced surface tension ·
Oil film prevents oxygen entering water. ·
Oil is toxic, absorbed via digestive system and
lungs. Can accumulate through food
Coating feathers and fur results in reduced insulation
/ flight/ buoyancy. ·
Set aside -
SSSI?s and nature reserves- havens for
threatened species. ·
programmes – to allow release into wild. ·
Changes in agricultural