Human impact on the environment
Humans have an enormous impact on the world we live in, some of it good, a lot of it bad. This topic is obviously very closely linked to what you will see on television and read about in the news, so it is incredibly important that you make sure you are taking note of what is going on in the world around you.
In an exam you might well be asked to give arguments for and against various issues surrounding the impact of humans on the environment. Make sure you are able to do this in a balanced way.
In an exam you might well be asked to give arguments for and against various issues surrounding the impact of humans on the environment. Make sure you are able to do this in a balanced way.
Countryfile is a great programme to watch on Sunday nights in order to keep up-to-date with environmental news in the UK
|
The human population explosion
Humans have been on earth for less than a million years, but it is only within the last 200 years or so that their has been an enormous population boom. The human population is currently approximately 7 billion and growing...fast!
Normal population controls such as
Exam Q practice: Suggest reasons why the population has increased so rapidly over the last couple of hundred years
Population growth and an increase in the standard of living has had an enormous impact on earth. Brief details are in the table below, and we will look at them in more detail after:
Humans have been on earth for less than a million years, but it is only within the last 200 years or so that their has been an enormous population boom. The human population is currently approximately 7 billion and growing...fast!
Normal population controls such as
- predators
- lack of food
- build up of waste
- disease
Exam Q practice: Suggest reasons why the population has increased so rapidly over the last couple of hundred years
Population growth and an increase in the standard of living has had an enormous impact on earth. Brief details are in the table below, and we will look at them in more detail after:
Factor
Use of vast amounts of energy (and so burning of fossil fuels) > Increased transport usage (planes, trains and automobiles) > Need for space to live, work and for transport routes > Farming requirements > Quarrying for rocks and metal ores > Generation of enormous amounts of domestic and industrial waste > |
Impact on environment
Pollution Pollution Destruction of habitats Destruction of habitats Destruction of habitats Destruction of habitats & pollution |
Polluting the land
There are many ways in which humans pollute the land:
|
Polluting the water
The increase in the use of fertilisers to meet the demands for food production have had sometimes catastrophic effects on our waterways. Eutrophication is one such consequence that you need to know about.
Eutrophication - the process by which excessive nutrients in water lead to very fast plant growth. When the plants die they are decomposed and this depletes the water of oxygen, meaning it can no longer sustain life
The increase in the use of fertilisers to meet the demands for food production have had sometimes catastrophic effects on our waterways. Eutrophication is one such consequence that you need to know about.
Eutrophication - the process by which excessive nutrients in water lead to very fast plant growth. When the plants die they are decomposed and this depletes the water of oxygen, meaning it can no longer sustain life
NOTE: untreated sewage which is very high in nitrates can also cause eutrophication. Eutrophication is not the result of toxic chemicals. It is caused by fertilisers just as much as it is caused by organic waste.
There is a lovely diagram on the BBC Bitesize site if you want to have a look |
|
Toxic chemicals such as herbicides and pesticides can also be washed into waterways and, as mentioned above for land pollution, can have a bioaccumulative effect within the aquatic food chains (this often happens in fish with mercury levels). Farmers in the UK have strict controls on the use of chemicals to limit these effects
Make sure you know how water quality can be tested, and about the use of freshwater invertebrates as indicator species for clean/dirty water. We did this in the 'Environmental Change' topic
Make sure you know how water quality can be tested, and about the use of freshwater invertebrates as indicator species for clean/dirty water. We did this in the 'Environmental Change' topic
Polluting the air
Air pollution affects every living organism. It is mainly caused by the combustion of fossil fuels (oil, natural gas and coal) and petrol, diesel and aviation fuel (derived from crude oil).
There are 3 main forms of air pollution:
Air pollution affects every living organism. It is mainly caused by the combustion of fossil fuels (oil, natural gas and coal) and petrol, diesel and aviation fuel (derived from crude oil).
There are 3 main forms of air pollution:
- Acid rain
- Global dimming
- Smog
Formation of acid rain
When fossil fuels are burnt, they release carbon dioxide and sulphur dioxide into the atmosphere. In addition, at high temperatures (eg. car engines), nitrogen oxides are released. Sulphur dioxide and nitrogen oxides:
|
Effects of acid rain
Direct effects - falls onto trees, leaves and flowers and soaks into soil and acts to kill the plant Indirect effects - acidifies waterways (rivers, ponds, etc) making them too acidic for plants and animals to live there Factories, power stations and vehicles are responsible for much of the acid rain formation, and this is very difficult to control. As gases are carried on the wind, the pollution generated by one country can cause problems in another one. So, countries that have strict controls on pollution might still have acid rain from their dirtier neighbour, while somebody else benefits from their clean air! |
Reducing air pollution
|
Bioaccumulation is the build up of toxic chemicals in animals as you progress up through the food chains. It can happen in land food chains with, for example, herbicides and pesticides that are used by farmers. It is also very common in aquatic food chains where heavy metals such as mercury build up in the higher fish, such as sharks and tuna.
It is the result of the body's inability to break the chemicals down. Therefore, at each stage of the food chain, more and more toxins build up in the organisms. Top predators have the highest levels of chemicals.
It is the result of the body's inability to break the chemicals down. Therefore, at each stage of the food chain, more and more toxins build up in the organisms. Top predators have the highest levels of chemicals.
Bioaccumulation is the reason why pregnant women are advised to limit their intake of higher fish, such as shark, marlin and tuna. These fish commonly contain high levels of mercury which can cause problems with an unborn baby
The video below explains bioaccumulation nicely
The video below explains bioaccumulation nicely