REARRANGED ORDER - Pollution and Global Warming (GCSE Biology)

Pollution and Global Warming

Pollution

• Pollution can take many forms: water, air and land.
• Water pollution occurs in bodies of water. There are many ways in which water pollution occurs. When farmers use fertilisers, insecticides and herbicides, water can run off from their fields into early bodies of water during periods of heavy rain. This can settle in the water leading to eutrophication.

Eutrophication

1. Fertilisers are used by farmers. Fertilisers provide nutrients to help farmers promote good crop growth.
2. Fertilisers are carried by rain water. These fertilisers can get mixed in with rain water which carries them to nearby bodies of water.
3. Fertilisers enter lakes and rivers. When the fertilisers get into lakes, rivers, and streams, they lead to a spike in nitrogen, ammonia, and other nutrients in the water.
4. Nitrogen spike kills aquatic animals. This spike in nutrients and nitrogen is beneficial to aquatic plants which causes them to grow very rapidly and densely. However, nitrogen and ammonia are toxic to other aquatic organisms.
5. Overgrowth of plants. The over growth of plants removes oxygen from the water.
6. Large loss of aquatic animals. Ultimately, eutrophication leads to large scale die off of aquatic organisms, and eventually the plants themselves.

Other Pollution Methods

• Sewage can also enter waterways. In parts of the world with open sewers, human waste may enter the streams and rivers. This can cause severe illness such as cholera.
• Hormones in water courses can impact organisms. For example, the urine of women on contraceptive hormones contains oestrogen, and if untreated, it can remain in the sewage and can travel to rivers and cause the feminisation of organisms that are sensitive to oestrogen. The oestrogen can also end up in tap water and, in the long term, it is thought to reduce the sperm count in men.
• Air pollution comes from smoke and toxic gases. As we burn more fossil fuels, we send more and more sulphur dioxide and carbon dioxide into the air. These are greenhouse gases and lead to global warming. Moreover, they can combine with water in the clouds to form acid rain. This destroys many plants and monuments. It could even acidify bodies of water. This huge amount of air pollution has led to smog. This can be dangerous to humans. The lungs of people living in central London have been known to take a lot of damage due to the pollution.
• Land pollution comes from landfill and toxic chemicals. As the human population grows, there is an increase in the waste produced. When you put something in your bin, it is more often than not placed in a landfill site. Batteries cannot be disposed of in this way. When they make their way into landfill, their acid can lead, polluting the land. Non-biodegradable plastic in the environment can also affect aquatic organisms and those on land e.g. by destroying their habitat, trapping them or contaminating their food chain.

Assessing Levels of Pollution

Indicator species can be used to assess the levels of pollution. These species are sensitive to changes in the environment so can be good indicators when exploring the effect of human activity:

• Bloodworms and sludge worms can help indicate polluted water. These species are adapted to live in polluted water so when water pollution is high, the number of these organisms will be high too.
• Freshwater shrimps and stonefly can help indicate clean water. These species are adapted to live in clean water and are sensitive to oxygen concentrations so if you find these species in water, it will tell you that the water is clean.
• Different species of lichen and blackspot fungus on roses can help indicate air quality. These species are sensitive to sulphur dioxide concentrations in the air. If you find a greater number of these, it will indicate that the air is clean.

GCSE Biology Online Course

Covering every topic in the GCSE syllabus

Buy Now£29

Global Warming & Climate Change

The Use of Fossil Fuels

The use of fossil fuels leads to the greenhouse gas effect which in turn causes global warming. Global warming causes the temperatures on Earth to increase drastically.

Carbon dioxide, water vapour, nitrous oxide, CFCs and methane are greenhouse gases. They act by insulating the earth, thus causing an increase in temperature over time.

These increases in temperature have had many negative consequences on the Earth.

• Weather patterns have changed, thus changing migration patterns
• Tropical diseases have spread to regions without immunity
• The polar ice caps are melting, leading to a rise in sea level

Climate Change and Ecosystems

Changes in climate negatively impact ecosystems:

• Organisms aren’t adapted to the new climate. Many plants and animals require very specific climates in order to survive. Changing the climate results in a loss of suitable habitat which can cause these organisms to become extinct.
• Certain organisms can outcompete. Organisms better suited to warmer temperatures can outcompete other animals for resources and habitats, which also results in a loss of biodiversity.
• Increase in diseases. Climate change can promote the proliferation of many disease-causing organisms such as mosquitoes, mould, viruses, bacteria, and other parasites. This can harm not only other plants and animals, but also humans.
• Acid rain can impact the environment. The build up of sulphur dioxide in the atmosphere can lead to it being mixed with rain clouds and causing acid rain. The main causes of this are power stations and car combustion engines. The acid rain can cause acidic lakes which can impact organisms and also trees that aren’t adapted to survive at a low pH.