Sources of Chemical Substances as Contaminants and Pollutants

Nature may be responsible for generating pollutants when natural substances are liberated in amounts that can harm health or cause alterations in ecosystems. This is the case with volcanic eruptions that generate abnormal levels of particles and gases in the atmosphere. Processes such as wind erosion and natural anaerobic processes (involving the production of CO2, CH4, and H2S) may also contribute to abnormal levels of natural substances. Other examples include  

Effects of Pollutants on the Chemistry of the Atmosphere, Hydrosphere, and Lithosphere 

The main sources of anthropogenic pollutants derive from the following human activities  

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