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Environmental pollutants are constituent parts of the pollution process. They are the actual “executing agents” of environmental pollution. They can come in gaseous, solid or liquid form.
It is interesting to note that, as of 1990, there were around 65,000 different chemicals in the marketplace, i.e. potential environmental pollutants that were to be released into air, water and land on a regular basis. (1)
Renowned author Miguel A. Santos identifies four general characteristics of environmental pollutants (2):
These points emphasize that pollutants present a serious long-term global problem that affects more or less every country and, therefore, can only be solved by a coordinated set of actions and unwavering commitment of nations to international environmental agreements.
In order to develop and implement an effective international policy for pollutants’ management, it is important, among other factors, to understand their decomposition mechanisms.
We know that decomposition of pollutants can occur either biologically or physicochemically. (3)
Santos divides those pollutants that can be decomposed biologically into biodegradable and non-biodegradable, and describes them as follows. (4)
Biodegradable Pollutants
Biodegradable pollutants are the ones that can be broken down and processed by living organisms, including organic waste products, phosphates, and inorganic salts.
For example, if a pollutant is organic, it can be used by a living organism to obtain energy and other material from carbohydrates, proteins etc.
Therefore, biodegradable pollutants are only “temporary nuisances” that can be neutralised and converted into harmless compounds.
However, it is important to remember that they can be serious pollutants if released in large amounts in small areas, thus exceeding the natural capacity of the environment to “assimilate” them.
Non-Biodegradable Pollutants
Non-biodegradable pollutants are the ones that cannot be decomposed by living organisms and therefore persist in the ecosphere for long periods of time. They include bottles, cans, plastics, metal, some pesticides and herbicides, and radioactive isotopes.
Non-biodegradable pollutants are dangerous because living organisms have neither enzymes capable of processing these pollutants nor defensive systems against them.
In addition to that, fat soluble (but not water soluble) non-biodegradable pollutants (such as chlorinated hydrocarbons, benzene etc) are not excreted with urine but are accumulated in the fat of living organisms and cannot be metabolised.
Therefore, the organisms retain 100% of these toxins (pollutants). The toxins are then circulated throughout the food chains via the process of biomagnification. For example, plant-eating animals (herbivores) will eat intoxicated plants; meat-eating animals (carnivores, including humans) will eat herbivores and will absorb the toxins already accumulated in the herbivores’ bodies. This is how humans can get high concentrations of toxins from their food sources, with all the negative consequences following such consumption.
Non-biological decomposition of pollutants requires a complex combination of factors, such as wind, water and climate to work together to achieve neutralisation of pollutants.
Some of the most dangerous pollutants such as radioactive isotopes ca n decompose by themselves but it will take them thousands of years.
Whereas biological and non biological methods of decomposition may apply to solid and liquid pollutants found in water and land, the case is slightly different for air pollutants.
There are two ways in which air pollutants may be removed from the atmosphere – wet deposition and dry deposition. The Air Pollutants Overview article has more detail on it.
We may assume that once air pollution has been deposited to the surface of the Earth (made up of water and land), the normal rules of biological and non biological decomposition for other types of pollutants will apply.
For example, acidification of lakes and streams via acid rain can cause destruction of fish which are incapable of processing pollutants delivered by acid rain.
Pollutants can also be grouped according to what they affect: biocides (“life killers”) and locucides (“location killers”). (6)
Biocidic pollutants affect living organisms directly, whereas locucidic ones may produce negative impacts on large geographical areas which makes them a lot more dangerous than biocides.
Last update: April 2008
