A3.4.3 Adverse Effects of Pollution on Water
Different species live in different types of water. The most obvious difference is salt water and freshwater. However, there are a number of different characteristics that determine the success of species living in a water body. These include issues such as Oxygen. Oxygen levels in the water are affected naturally by the presence of plants and animals in the water; the speed of water flow; temperature, salinity and turbulence. However, the addition of chemicals to a water body can affect the oxygen levels. The upset of the natural state of a water body will affect the animals that can survive there, affecting biodiversity.
Pollution to water can again be industrial releases directly into a water body, through discharge or accidental spillages. This of course could consist of any polluting material, including chemicals or oil. Oil is highly polluting and it only takes a tiny amount to pollute a large water body.
Some industrial operations use water for cooling, which is then discharged as warm or hot water. If this warmer water was discharged directly into a watercourse it could kill the animals living in it, as the temperature range that animals can survive in is a limited range.
Acid deposition may also affect water bodies. It may enter a water body through directly landing in it, or more commonly, through landing on soil and then leaching through the soil into water bodies.
The acidification of freshwater can have toxic effects on flora and fauna. Some species of algae may be unable to survive, whilst others may flourish. This leads to a reduction in biodiversity.
Changes in algae levels affect the amount of sunlight that reaches the bottom. The additional of suspended solids in water may have the same affect. Cloudy water reduces the amount of sunlight penetrating the water, disrupting the growth of photosynthetic plants and micro-organisms. This has subsequent effects on the rest of the aquatic community that depend on these organisms to survive.
Certain species of animals are more susceptible to changes in acidity than others. For example, salmon and trout will find it hard to survive in water with a high pH, whilst pike and eel are more resistant. Again, this affects the biodiversity of the area.
Industrial waste often contains many toxic compounds that damage the health of aquatic animals and those who eat them. Some toxins affect the reproductive success of marine life and can therefore disrupt the community structure of an aquatic environment.
The application of fertilisers on farmland can pollute water, as the nitrogen in the fertiliser is washed into watercourses. This may lead to Eutrophication.
Eutrophication
Eutrophication promotes excessive plant growth and decay. Simple algae and plankton find it easier to survive, causing a reduction in water quality. Dissolved Oxygen levels decrease and water becomes cloudy. Species struggle to survive (through suffocation) leading to a loss of biodiversity.