Zusammenfassung der Ressource
Properties of Pollutants
- Toxicity
- A measure of how poisonous a substance is, usually caused by enzyme inhibition
- If biological reactions controlled by proteins and enzymes
cannot take place then the affected cells may malfunction
- Specificity
- A measure of differing toxicities of a substance on different organisms
- A specific substance is very toxic to some organisms but much less toxic to ohers
- Persistance
- A measure of the rate at which a material breaks down
and therefore the length of time it remains in the
environment
- Does not apply to elements that cannot
break down under normal environmental
conditions - non degradable
- CFCs and DDT are good examples
of persistent chemicals - they can
take decades to break down
- Biodegradability
- The ease with which a material is broken
down by living organisms, usually bacteria
- Mobility
- A measure of how easily a material
moves through the environment
- Highly mobile pollutants can travel longer distances,
causing problems over larger areas, although they
may also be diluted and become less locally harmful
- Solubility
- The ease with which the
molecules of a material separate
and disperse into a liquid
- These materials are very mobile in the
hydrosphere - lakes, rivers, oceans, etc
- Liposolubility - A measure of how easily a substance
dissolves in fats and oils
- These materials (e.g. PCBs, mecury, lead,
organochlorine insecticides) be stored for
long periods of time in living organism
- Bioaccumulation
- The increase in concentration of a substance in living tissue
- Chronic exposure to small doses over long
periods of time may result in bioaccumulation.
This occurs most often with liposolubles.
- Biomagnification
- The progressive bioaccumulation of a material along a food chain
- Synergism
- The process where the presence of two
materials produces a greater effect that
the sum of their individual effects
- Synergism is difficult to predict and although there are some
known examples (zinc and cadmium) it is impossible to test
out all possible combinations to which we are exposed
- Mutagenicity
- A mutagen is a material that can
cause changes in DNA structure
- If gametes are affected then babies
produced may have birth abnormalities that
could be passed on to future generations
- Carcinogenicity
- A carcinogen is a mutagen that causes body cells to
start to multiply in an uncontrolled way (cancer)
- Teratogenicity
- A substance that interferes with gene function
in a growing embryo so that a non-inherited
birth abnormality is produced
- Primary/Secondary
- Primary pollutants are pollutants released from direct human
activity e.g. carbon dioxide from burning fossil fuels
- Secondary pollutants are pollutants produced
through chemical reactions between primary
pollutants e.g. PANs