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1.5. HUMANS AND POLLUTION (Knowledge and Understanding (Pollution is a…
1.5. HUMANS AND POLLUTION
Knowledge and Understanding
Pollution is a highly diverse phenomenon of human disturbance in the ecosystem
Pollution - addition of a substance or agent to an environment by human activity, at a rate greater than that at which it can be rendered harmless to the environment
Management strategies can be applied at different levels
Pollution may be organic or inorganic substances, light, sound or heat energy or biological agents/invasive species
Pollution can be point source or non-point source, persistent or biodegradable, acute or chronic
Pollutants may be primary (active on emission) or secondary (arising from primary pollutants undergoing physical or chemical change)
Pollutants and pollution
Types
Matter (gases, liquids, solids) which is organic (contains carbon atoms) or inorganic
Energy (sound, light, heat)
Living organisms (invasive species or biological agents)
Primary pollutants - active on emission e.g. carbon monoxide from incomplete combustion of fossil fuels - causes headaches, fatigue and can even cause death
Secondary pollutants - formed by primary pollutants undergoing physical or chemical changes e.g. sulphuric acid forms when SO3 reacts with water
Major sources of pollutants
Combustion of fossil fuels
carbon dioxide, sulphur dioxide, nitrogen oxides, photochemical smog including tropospheric ozone
Leads to increase in GHGs - climate change, acid deposition - tree and fish death, respiratory disease in humans, eye itrritation carbon monoxide - binds with haemoglobin in red blood cells instead of oxygen which can lead to death by suffocation
Industrial waste
Heavy metals, fluorides, heat, lead and acids
Leads to poisoning e.g. lead/mercury, reduces solubility of gases in water so less oxygen is available - organisms may die
Domestic waste
Organic waste (food and sewage), waste paper, plastics, glass, tins/cans
Eutrophication and water borne diseases, materials fill up landfill sites
Agricultural waste
Nitrates, organic waste, and pesticides
Leads to eutrophication, spread of disease and bioaccumulation up food chains
Point source and Non point source pollutants
NPS
released from numerous, widely dispersed origins
Many sources, virtually impossible to detect where it came from
Air pollution can be blown hundreds of kms and chemicals released from open chimneys mix with those from others
Rainwater can collect nitrates and phosphates which are spread as fertiliser as it infiltrates the froung or as runoff on the surface - travels many kms before draining into a lake or river
PS
Released from a single clearly identifiable site e.g. factory chimney or waste disposal pipe releasing sewage into a river
Easier to identify who is polluting therefore easier to manage
Persistent organic pollutants and biodegradable pollutants
POPs usually manufactured as pesticides - resistent to breaking down and remain active in the environment for a long time - so they bioaccumulate in animal and human tissues and biomagnify in food chains
e.g. DDT, aldrin, PCBs etc.
High molecular weight, not very soluble in water, highly soluble in fats and lipids - can pass through cell membranes
Halogenated molecules - often with chlorine
Biodegradable pollutants do not persist in the environment and break down quickly - may be broken down by decomposer organisms or physical processes e.g. light or heat
e.g. soap, domestic sewage, biodegradable plastic bags made of starch
Acute and Chronic Pollution
Acute - large amounts of pollutants are released causing a lot of harm e.g. Bhopal disaster in India
Chronic - long term release of a pollutant but in small amounts - often goes undetected for a long time, usually more difficult to clean up, spreads widely e.g. air pollution causing problems such as asthma, bronchitis etc.
Detection and monitoring of pollution
Pollution can be measured directly or indirectly
Direct - record the amount of a pollutant in the water, air or soil
Direct examples - measuring acidity of rainwater, amount of gas e.g. CO2 in the atmosphere, amount of particles emmited by a diesel engine (AIR POLLUTION) nitrates and phosphates, amount of organic matter or bacteria, heavy metal concentrations (WATER OR SOIL)
Indirect - record changes in an abiotic or biotic factor which are the result of pollutants e,g, measuring oxygen content of water or recording presence or absence of indicator species e.g. leafy lichens on trees found in unpolluted conditions
Pollution management strategies
Changing human activity that produces it
Regulating or preventing the release of the pollutant
Clean up or restore damaged ecosystems