Knowledge of the natural occurrence of elements is necessary in determining the degree of pollution. The natural spatial variation of chemical compounds in soil, water or vegetation is often being neglected in pollution debates. It is inaccurate to assume that high concentration levels of heavy metals only can be due to pollution.
Local pollution sources can often be identified by a known source (like this one), while long range transported pollution can prove more difficult to distinguish from natural distribution patterns.
All ore deposits show that in some areas a high content of certain chemical elements occur naturally, which exceed the mean content of the Earth's crust.
Exceed the normal values
You often find several ore deposits within smaller or bigger provinces. A Norwegian example of such a province is the Trondheim belt with similar ore deposits in Røros Hjerkinn, Løkken, Fosdalen and Grong. Within this particular province, the concentrations of sulphur, iron, copper and zinc exceed the normal values.
An area where, for example, mercury is concentrated, is the Almandin-province in Spain. It can thus be concluded that knowledge of the natural occurrence of elements is necessary in determining the degree of pollution.
Local and long-range pollution
Flora and fauna adjust to the occurrence of chemical elements in bedrock and soil. Anthropogenic pollution can alter this balance by changing the relative distribution of the elements. Since pollution can be both local and long-range transported, it gives rise to both local and regional chemical variations in the environment.
The spatial distribution pattern for en element is in principle always an unknown combination of the contribution from natural and anthropogenic sources, and in some cases it will prove difficult to differentiate between these.
Local pollution sources can often be identified by a known source, while long range transported pollution can prove more difficult to distinguish from natural distribution patterns.
Published: 14. January 2008