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6. Human Impacts on the

Environment: Pollution

OBJECTIVES
> To understand that humans can alter their environment
> To understand how changes in human population have altered our impact on the environment
> To consider human impacts in terms of cause, effect and possible remedies

Humans already are, or could easily become, the When looking at pollution, we shall consider
most significant biotic factor in every environment. three key points:
Primitive humans had a temporary effect on the What is the cause?
environment - hunting, fishing and burning wood - What are the effects?
because they were nomadic and allowed the What are the solutions?
environment periods of time to recover. After humans Pollution of the atmosphere
became cultivators and settlers (thousands of years Two big problems with the Earth's
ago) the following `effects' on the environment atmosphere are:
gradually became noticeable: the greenhouse effect
The use of tools and the domestication of animals production of acid rain.
meant a more efficient agriculture. Burning of fossil fuels has a major effect on

The greater need for shelter, agricultural land and the atmosphere. The combustion process
fuel meant a greater rate of deforestation and oxidises elements and compounds in the fuel,
desertification. as shown in the equations below.
The careless use of pesticides and fertilisers,
together with increasing consumption of fossil
fuels, produced problems of pollution. These
have been added to by the development of
nuclear energy sources.
Humans may also have positive effects - we are able
to use our skills and knowledge in conservation.
Our demands on the environment

Human success, measured as an increase in
population size, is largely due to our ability to solve
complex problems and modify the environment for our These oxides affect the atmosphere - carbon
benefit. This places great demands on the dioxide is a greenhouse gas and sulfur dioxide
environment, causing changes in the atmosphere, and oxides of nitrogen contribute to acid rain.
the aquatic environment and the land. The other major pollutant of the atmosphere
Humans have also, intentionally or otherwise, is methane, produced by livestock (especially
seriously upset the balance of populations of other during intensive farming, see page 265).
living organisms. There are also localised problems with lead
Causes, effects and remedies for pollution compounds, and with smoke. The causes and

Pollution is any effect of human activities upon the effects of, and possible solutions to, each of
environment, and a pollutant is any product of human these problems are outlined in the diagrams
activities that has a harmful effect on the environment. opposite.

15 Learning Module Organisms and Their Environment | Class 11