The Nature of Pollution
- Pollution refers to the introduction of harmful substances or agents into the environment
- These substances cannot be rendered harmless by the environment at a rate that is greater than the rate of their release
- Pollution is harmful to organisms and can adversely affect normal environmental processes
- It is a major source of contamination of the Earth and atmosphere, making ecosystems and habitats toxic and unpleasant
- Pollution can be:
- Natural (e.g. ash from volcanic eruptions) or human in origin (e.g. microplastics)
- Intentional (e.g. industrial waste discharged into rivers) or unintentional (e.g. accidental oil spills from oil tankers)
- Pollution results from the release of substances that degrade the sustainable quality of air, water, and soil, negatively impacting human quality of life
Main Sources of Pollution
- Pollutants can come in various forms, including:
- Organic or inorganic substances
- Light, sound, or heat energy
- Biological agents
- Invasive species
- Human activities, including the combustion of fossil fuels, are the major sources of pollution
- Defining pollution levels is challenging and depends on the nature of the environment. For example:
- Oil slicks pose a more significant threat in Arctic areas than in tropical ones due to slower decomposition rates in colder environments
- Pollution levels that do not pose a risk to healthy adults can still affect young children, the elderly, or asthmatics
The Major Sources of Pollution
| Source | Type of Pollution | Activity | Effects |
| Energy Production | Sulfur dioxide, nitrogen oxides, particulates | Burning fossil fuels | Acid rain, photochemical smog, respiratory problems |
| Agriculture | Pesticides, fertilisers, animal waste | Spraying crops with pesticides, spreading fertilisers on fields, runoff from manure and silage | Bioaccumulation, biomagnification, eutrophication |
| Industry | Toxic spills and leaks | Industrial accidents e.g. chemical factories | Release of toxic substances into the environment e.g. Minamata, Japan and Bhopal, India |
| Domestic Waste | Solid domestic waste, sewage, chemical waste | Waste dumped in landfill sites, waste from toilets, household cleaning products | Contamination of groundwater, release of methane, eutrophication, disease |
| Transport | Exhaust fumes from vehicles, runoff from roads | Driving, fuel and oil leaks channelled into surrounding land and watercourses by road drainage | Air pollution, respiratory problems, climate change, contamination of streams and soils |
| Natural | Volcanic ash, particulate pollution | Volcanic eruptions, wildfires, dust storms | Respiratory problems, acid rain, habitat destruction |
Worked example
Construct a systems diagram to show the impacts of air pollution from the pollutants nitrogen dioxide and sulfur dioxide, focussing on the formation of acid rain and its effects.
Answer
Exam Tip
Although natural pollution can exist (e.g. in the form of ash from volcanic eruptions or dust from dust storms) the syllabus refers to pollution as the introduction of pollutants to the environment through human activity, so you should focus on revising human sources of pollution for your exams.
