properties of pollutants
- Created by: JasminePsych
- Created on: 19-02-18 12:31
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- properties of pollutants
- toxicity: a measure of how poisonous a substance is, (usually caused by enzyme inhibition).
- toxic pollutants
- carbon monoxide binds to haemoglobin in blood and prevents it from carrying oxygen.
- lead inhibits enzymes in nerve cells
- DDT prevents normal passage of nerve impulses between nerve cells by inhibiting enzyme action.
- acids change the shape of cell membrane and enzyme proteins so they don't function properly.
- toxic pollutants
- specificity: a measure of differing toxicities of a substance on different organisms. A specific substance is very toxic to some organisms and much less toxic to others.
- e.g. pyrethroid insecticides kill both insects and mammals, but insects are more sensitive than mammals so farmers use a dose that kills insects but won't harm mammals.
- persistence: a measure of the rate at which a material breaks down and therefore the length of time it remains in the atmosphere.
- CFCs are chemically stable and break down slowly
- DDT is stable but gradually breaks down, it hasn't been used for over 30 years but some still remains in wildlife
- both sewage and pyrethroid insecticides break down rapidly in the right conditions.
- biodegradability: the ease with which a material is broken down by living organisms, usually bacteria.
- sewage, paper and cardboard are biodegradable
- most plastics and DDT are less biodegradable
- mobility: a measure of how easily a material moves in the environment.
- CFCs are persistent gases which travel long distances in the atmosphere as they aren't very soluble in water so aren't removed by rain
- smoke particles rarely travel far as they are washed out by rain or settle due to gravity
- currents in rivers will carry sediments, smaller\lighter particles travel furthest
- solubility: the ease with which the molecules of a material separate and disperse into a liquid.
- nitrate fertilisers are very soluble in water so get washed off fields by rain and carried into local river bodies
- liposolubility: a measure of how easily a substance dissolves in fats and oils.
- organochlorine insecticides, dioxins and PCBs are liposoluble
- heavy metals are liposoluble,e.g. mercury and lead
- bioaccumulation: the increase in concentration of a substance in living tissue.
- organochlorine insecticides, dioxins, PCBs, and heavy metals like lead and mercury
- biomagnification: the progressive bioaccumulation of a material along a food chain.
- insecticides like DDT can biomagnify
- synergism: the process where the presence of two materials produces a greater effect than the sum of their individual effects.
- nitrogen oxides, sulfur dioxide, zinc and cadmium are synergistic
- mutagenicity: a mutagen is a material that can cause changes in DNA structure.
- ionising radiation, asbestos, dioxins and PCBs are mutagenic
- carcinogenicity: a carcinogen is a substance that can cause cancer.
- asbestos, DDT and cadmium are carcinogenic
- teratogenicity:a teratogen is a substance that interferes with gene function in a growing embryo so that a non-inherited birth abnormality is produced.
- the herbicide 2,4,5T is a teratogenic pollutant- it was used in defoliant spray used by the USA in the Vietnam war and to control broad-loaf weeds
- mercury is teratogenic
- toxicity: a measure of how poisonous a substance is, (usually caused by enzyme inhibition).
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