The previous answer gives a good overview of different ways in which pollution can be classified. However it appears to have missed out on the specific issue raised in the question - that is classifying pollution according to ability of nature to decompose the polluting substances into other harmless material. As per this criteria, pollutants are generally classified as biodegradable and non-biodegreadable.
Biodegradable pollutants consists of substances that over a time get converted to broken down into other harmless substance by action of plant and animals in the nature. In this process a major role is played by micro organisms such as bacteria and fungi. It may also include some natural chemical action on substances as they come come in contact with chemicals naturally present in soil or water. However, it should be noted that biodegradation is a slow process and the nature has a limited capacity to cleanse itself of such pollutants. Therefore, too much of biodegradable material released too fast in the environment also poses serious threats to the environment, including permanent damage ability of ecosystem to cleanse itself.
Non-biodegradable pollutants or substances do not breakdown under the natural action of plants and animals. Due to this the non-biodegradable substances released as wastes of human activity keep on accumulating. The total quantity of some of such materials - for examples plastic of different types - pose a very serious pollution today.
Pollution has been defined as "any introduction in the environment by man, directly or indirectly, of some of the substances or energy with deleterious effects, likely to endanger human health, damage the biological resources, ecosystems and material properties, to reduce benefits or to prevent other legitimate uses of the environment.
1. Natural pollution - has secondary importance in conditions where the contribution of anthropogenic pollutants is becoming more serious.
a) volcanic eruptions issue gas, vapor, solid particles that are transported long distances by wind and air currents.
b) Soil erosion, caused by wind or rain, is the more intense the more the soil is devoid of vegetation, in slope or in an area with rich basin network.
c) plant and animal residues release, by decomposition, a number of polluting gaseous substances. Pollen or fungi may be natural aerosols that adversely affect human population health.
2. Artificial Pollution
Initial pollutant products were of organic nature and easily biodegraded by bacteria and fungi.
Along with industrial development and population explosion appeared non-biodegradable waste, for which no enzymes exist in nature capable of decomposition.
Pollutants may be of different nature:
- Physical (heat, ionizing radiation, noise, etc..)
- Chemical (pesticides, oil, metals, organic substances, etc..)
- Biological (pathogens: viruses, bacteria, fungi).
Depending on their state of aggregation, the pollutants can be:
The volume of pollutants that are assaults environment and the pollution intensity are in direct proportional report with growing of number of humanity and its requirements, several requirements being created and maintained artificial.Pollution grows exponentially, as new pollutants factors coming into action, due to the combined effect of their action.
It is very difficult to inventory the number of all polluting factors acting in one way or another, at some point, and to assess the amounted outcome of their action. There are no known limits of resilience of ecosystems and Ecosfera