4.4.1 The Effects of Pollution Flashcards
Human population growth globally has been increasing exponentially for the last, how long?
for the last 150 years
There are many reasons for this exponential growth, including:
1. Improved technology leading to an abundance of food = rapid increase in birth rate
Rapid growth in the human population and an increase in the standard of living means, what?
our negative effect on the environment is also increasing
As increasingly more resources are used to sustain the growing human population, what happens?
more waste is produced and more pollution is created
Unless waste and chemical materials are properly handled, what will happen?
pollution will continue to be created
What is the Source/Cause of Toxic Chemicals (Pesticides and Herbicides)
Source/Cause:
Sprayed on crops to prevent damage by insects and growth of weeds. Runoff occurs from agricultural land if these tocic chemicals are applied in too high a concentration causing them to enter water courses
How do Toxic Chemicals affect Biodiversity
1. These chemicals cannot be broken down by organisms.
- This is called bioaccumulation.
- This is called biomagnification
What is the Source/Cause of Untreated Sewage
Lack of sewage treatment plants in inhabitated areas (due to poor infrastructure or lack of money) meaning sewage runs or is pumped into watercourses
What is a watercourse
watercourse is the channel that a flowing body of water follows ie, river, lake, stream.
How does Untreated Sewage affect biodiversity
Sewage provides a good source of food for bacteria which increase rapidly, depleting the oxygen dissolved in the water (as they respire Aerobically)
This lack of oxygen eventually results in the death of aquatic organisms such as fish and aquatic invertebrates. This is known as Eutrophication
What is Eutrophication?
Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients
What is the Source/Cause of Fertilisers
Runoff occurs from agricultural land if fertilisers are applied in too high a concentration, causing fertilisers to enter watercourses
Define agricultural
used for farming or relating to farming
How do Fertilisers cause biodiversity
Fertilser causes increased growth of algae and water plants. The resulting ‘algae bloom’ blocks sunlight so water plants on the bottom start to die, as does the algae when competition for nutrients becomes too intense. Dead plants and algae are a good soruce of food for bacteria. As described above, this eventually leads to eutrophication and the death of many aquatic organisms.
What is the source of Toxic Chemicals (Land Pollution)
When sprayed onto crops, these toxic chemicals also get into the soil.
How do Toxic Chemicals (Land Pollution) affect biodiversity
These chemicals cannot be broken down by organisms. They can be absorbed by plants or taken in by other organisms living in the soil and can build up tissues of these organisms over time. This is called bioaccumulation, At each stage of the food chain, increasing levels of the chemicals build up in organisms, which can eventually build up to dangerously toxic levels in top predators, leading to death or failure to breed. This is called biomagnification.
What is the source/cause of Discarded Rubbish
Household waste that cannot be recycled is bured in landfill sites.
How does Discaded Rubbish affect Biodiversity
Landfill site take up a lot of room and their creation often results in the destruction of natural habitats. Toxic chemicals can spread from the waste into soil. Much rubbish, such as that made from plastic, is non-biodegradable and remains in the enviroment for hundreds of years.
What is a landfill site?
A landfill site, also known as a tip, dump, rubbish dump, garbage dump, or dumping ground, is a site for the disposal of waste materials
What is the source/cause of Sulphur Dioxide and Nitrogen Oxides
Combustion of fossil fuels that contain sulphur impurities creates sulphur dioxide. Nitrogen oxides are also fuel combustion. These gases react with oxygen and dissolve in rainwater to produce dilute sulphuric acid and nitric acid, which leads to acid rain.
How does Sulphur Dioxide and Nitrogen Oxides affect biodiversity
Acid rain can damage the leaves, buds, flowers and roots of trees and other plants. It can make rivers and lakes to acidic, resulting in the death of certain aquatic organisms. It can also cause the leaching of minerals that are toxic to fish, such as aluminium, into lakes.
Exam Tip
Water pollution from sewage and water pollution from fertiliser runoff have the same end result (increase in decomposing bacteria leading to a decrease in dissolved oxygen and death of aquatic organisms) but they do not arrive at this point in the same way.
You need to learn both and be aware of the differences between them. A common misconception is that sewage pollution also causes growth of water plants and algal blooms – this is very rarely the case, only runoff of fertiliser does this.
