Geochemical mapping
Why?
Metals and other substances are constantly circulating in nature all around us. Many of them derive from the bedrock or soil layers, others have been released as a result of human activities. Obviously, these substances make an impact on nature and the humans who live there, for better or worse.
One object of SGU’s geochemical mapping activities is to study Sweden’s soil geochemistry, i.e. the natural concentrations of metals and other important substances in soils. This information shows, for example, where there are areas that are deficient in certain substances or where there is a risk of elevated concentrations.
Another important aspect is biogeochemistry, i.e. element cycles in nature. SGU measures the total concentrations of metals and other substances that naturally circulate in the environment and the quantities of substances that are spread by air pollution or other emissions.
The information from both soil geochemical and biogeochemical mapping is used, inter alia, in mineral exploration, forestry, soil research, local authority planning, environmental monitoring and medical research.
How?
In order to find out the natural concentrations of main and trace elements in soils, samples are taken at a depth of about 1 metre. The samples are analysed in laboratories and the concentrations of more than 30 elements, as well as acidity (pH), are measured in each sample. The current sampling density is one sample per 6–7 km 2.
In order to determine the total concentrations of various substances in circulation, that are partially available for uptake by plants and animals, we analyse the roots of specific living plants and aquatic mosses in small watercourses. The current sampling density is one sample per about 6–7 km 2 and more than 30 elements are analysed.