1.5 Humans and pollution

Significant ideas:

Pollution is a highly diverse phenomenon of human disturbance in ecosystems.
Pollution management strategies can be applied at different levels.

International Mindedness

Pollution cannot be contained by national boundaries and therefore can act either locally, regionally or globally.

ToK

Experts sometimes disagree about pollution management strategies—on what basis might we decide between the judgments of the experts if they disagree?

Connections

ESS: Stratospheric ozone (6.2); photochemical smog (6.3); water pollution (4.4); terrestrial food production systems and food choices (5.2); human population carrying capacity (8.4); biodiversity and conservation (topic 3)

Diploma Programme: Chemistry (options A, B, C and D); Geography (option G); Economics

Knowledge and Understanding 1

Pollution is the addition of a substance or an agent to an environment through human activity, at a rate greater than that at which it can be rendered harmless by the environment, and which has an appreciable effect on the organisms in the environment.

Knowledge and Understanding 2

Pollutants may be in the form of organic or inorganic substances, light, sound or thermal energy, biological agents or invasive species, and may derive from a wide range of human activities including the combustion of fossil fuels.

Knowledge and Understanding 3

Pollution may be non-point or point source, persistent or biodegradable, acute or chronic.

Knowledge and Understanding 4

Pollutants may be primary (active on emission) or secondary (arising from primary pollutants undergoing physical or chemical change).

Knowledge and Understanding 5

Dichlorodiphenyltrichloroethane (DDT) exemplifies a conflict between the utility of a “pollutant” and its effect on the environment.

More detailed explanation...

Typical exam question: Define the term pollution.

Model answer: Any substance that is added to air, water, soil or food that threatens the health, survival or activities of humans and/or other organisms.

It can be in the form of matter or energy e.g. nitrates which cause algal blooms or an increase in temperature which will cause a decrease in the dissolved oxygen in bodies of water.

Pollution may be in the form of noise, seismic vibrations, light, thermal pollution, radio wave emissions, as well a chemical smells etc.

Typical exam question: Distinguish between the terms point source pollution and non-point source pollution, and outline the challenges they present for management.

Model answer: Point source pollution: comes from a single identifiable source e.g. a chimney, drainpipe, car exhaust.

Usually considered to be easier to manage as its impact is localised and legal action or responsibility can be easily attributed.

However point sources can be widely distributed and numerous so can be difficult to manage.

China investigates as truckloads of dead deformed pigs are dumped in rivers that supply drinking water to villages , Daily Mail, 17 March 2015. This is an example of point source pollution, but just because we can identify the polluter, doesn't necessarily mean it will not happen again.

Non-point source pollution: comes from dispersed and difficult to identify sources e.g run-off from farmland.

Difficult to assign responsibility and therefore manage the pollution.

Health alert as potentially lethal smog hits Britain, The Telegraph, 19 March 2015 . This is an example of non-point source pollution. Although the pollution comes from individual sources, it is impossible to identify them and therefore harder to prevent.

Find examples to summarise in the following table (don't forget the cite the source)

Typical exam question State the major sources of pollutants.

Model answer:

Examiners tips, make sure that you can:

Construct systems diagrams to show the impact of pollutants.
Evaluate the effectiveness of each of the three different levels of intervention, with reference to figure 3.
Evaluate the uses of DDT for anit-malarial and agricultural uses
With reference to figure 3, students should appreciate the advantages of employing the earlier strategies of pollution management over the later ones, and the importance of collaboration.

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