Pollution is defined as the addition of substances that harm the environment at a rate faster than it can be rendered harmless. Pollution can be natural or anthropogenic and come from point sources like factories that can be mapped, or non-point sources like vehicle emissions that are more dispersed. Major sources of pollution include sewage, mining, agriculture, industry, and waste. Pollution can seriously harm public health, water quality, soil quality, and lead to death in some cases. DDT was a widely used pesticide that was banned in many countries after being found to cause harm by weakening bird egg shells and linking to birth defects and cancer in other animals.

1. Topic 1
Foundations of Environmental
Systems and Societies
1.5 Humans and Pollution

2. Pollution
• The addition of a substance or an agent at a rate
greater than that at which it can be rendered
harmless by the environment, and having an
appreciable effect on organisms within it
(IB ESS guide)
• It may be:
– Natural (e.g. volcanoes)
– Anthropogenic (e.g. release of sewage)
– Deliberate or accidental
– May harm the quality of air, water or soil

3. Pollution
• Pollutants may be:
– Primary Pollutants (active upon emission)
– Secondary (primary pollutants which have
undergone some change in order to become
active)

4. Point Source Pollution
• Discrete sources of pollution which can be
pinpointed on a map
• May be more easily treated and managed, but
may be have a huge impact on the local
environment
– Chernobyl disaster, 1986
– Bhopal disaster
– A single sewage outfall

5. Non-point Source Pollution
• Dispersed sources of pollution
• Not possible to pinpoint a single origin
• Not easily managed
– Car pollution in a city
– Numerous industries in a single area

6. Major Sources of Pollution
sewage sludge (8%)
mining and quarrying
(27%)
agricultural waste
(20%)
industrial waste
(17%)
dredging waste
(11%)
domestic and
commercial waste
(9%)
demolition and
construction waste
(8%)

7. Effects of Pollution
• Death in serious cases
• Decreased level of public health
• Reduced water quality and availability
• Reduced soil quality
It is important that sources of pollution are tackled rather than the symptoms
http://www.youtube.com/watch?v=iyckJOd9A
es&list=PL51D60810437D8150

8. Case Study: DDT
• Dichlorodiphenyltrichloroethane
• An organochlorine insecticide
• Very non-polar
• Similar in structure to oestrogen and therefore has
´feminising’ effects on animals
• In birds it weakens egg shells so that the parents
break them as they try to incubate the eggs
• The birds at highest risk are those close to the top
of the food chain
• It was banned in most developed countries in the
1970s and 1980s
• It is now known to cause birth defects, damage to
the nervous system and cancers
• It is still used in many poorer countries to control
insect problems – why?
http://edroness.blogspot.mx/2013/10/biomagnification.html
http://edroness.blogspot.mx/2013/10/the-story-of-ddt.html

9. Pollution Management