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_______ occurs when substances are added to our surroundings which can harm living things
The main areas of the environment that are affected by pollution are:
The main sources of pollution are:
As _______ becomes a larger problem steps are being taken to try to control its effects. An example of domestic pollution is the production of sewage.
As the human population _______, the production of sewage _______.
If sewage is dumped into rivers and streams, it can cause the _____ of animals in the water
To control domestic pollution, sewage is taken to a local sewage works and ______ before being passed into waterways.
One of the main causes of agricultural pollution is the overuse of ________ and ________ on crops.
If fertilisers and pesticides get washed into nearby rivers and streams they can cause an ________ growth in green algae called an _____ _____
_____ ______ can cause the death of fish and other animals living in the water
One of the major reasons for industrial pollution is the increasing production of ________ that is required to meet our increasing energy needs.
Electricity is produced in two main ways& both have adverse effects on the environment.
- burning of fossil fuels
- nuclear power
When fossil fuels are burned they release harmful gases which pollute the air. These gases include:
- _____ _____ which can dissolve in rain water to form acid rain
- _____ _____ which may be involved in global warming and climate change
- sulphur dioxide
- carbon dioxide
The pollution caused by burning fossil fuels can be reduced by ________ the smoke fumes before they are released into the air from the power stations. This scrubbing _______ the sulphur dioxide from the smoke fumes thus ________ the chance of acid rain being produced.
Nuclear power produces _________ wastes which continue to give out harmful radiation for many years after they are produced. If these radioactive wastes are not disposed of very carefully they can ______ into the environment and ____ living things.
If an accident occurred at a nuclear power station harmful _______ could escape into the surroundings causing a greater number of deaths from ______ and radiation _______.
The pollution caused by ______ ______ can reduced by sealing the radioactive waste in ____ containers and dumping them deep in the ocean.
Pollution can also be reduced by using alternative energy sources such as ____ ____ and ___________ _____ _____
- wind farms
- hydroelectric power stations
Organic waste, for example sewage is a ____ ______ for micro-organisms in water.
If organic waste is dumped into rivers the numbers of micro-organisms rapidly _______. The mirco-organisms quickly use up most of the oxygen in the water so that much ____ oxygen is available to the other animals living in the water.
If organic waste is dumped into rivers, the number of animals in the water _______ and the number of different species of animals present ________.
An ________ ______ is one which thrives under certain environmental conditions, for example high oxygen concentration. The presence of an indicator organism shows that the condition they need to thrive is ________ in the environment.
- indictator organism
Humans must manage the _______ resources of ecosystems in order to obtain food.
As the human population grows the demand for food also grows. Sometimes this demand has led to poor management practices which can have consequences such as _______ and __________
Examples of poor management of resources include:
_________ of fish stocks;
_________ of grasslands
When fishermen ________, they catch too many fish which leads to a _______ in the stocks of fish like cod and herring. This can lead to the _______ of the fish populations.
The European Union has tried to ________ the effects of __________ by introducing annual quotas of fish that can be caught by different countries in the EU. It is hoped that this will allow the stocks of fish to recover.
If too many animals are allowed to graze grassland the _________ plants die and the soil is no longer held in place. This can lead to ____ ______ and ____ ______ because there is no soil to hold the new plants. This in turn can lead to ______
- soil erosion
- crop failure
Improvements for plants can be brought about by:
better ____ ___________,
____ ________ and
the use of _____ ______ _______.
- land management
- crop rotation
- modern farming methods
In order to maximise the yield of a crop a farmer must control the components of the farm ecosystem. There are two main components to be controlled:
_____ of _______ and
the ________ of the crop plants
- supply of nutrients
The supply of soil nutrients to the crop plant can be controlled by:
- adding _____ either natural or artificial to the soil;
- adding ____ which is organic material formed by decomposing organisms and which helps to improve the soil’s water holding capacity.
Supplying soil nutrients in this way increases the growth of the plants.
In order to maximise crop yield farmers grow one crop in a field; this is known as a _________.
- clearing the land of weeds using weedkillers;
- cultivating (digging up) the land;
- controlling the soil pH;
- maintaining the water content;
- building fences;
- putting up scarecrows;
- spraying the crops with pesticides