The loss of basic cations by leaching, in wet soils, brings about a reduction in the pH, which may lead to the bioavailability of elements, such as aluminium and manganese, which are toxic to plants when the pH is less than 5.5, and also heavy metals. To find acidic soils in Catalonia, it is necessary to go to high mountain areas (the Pyrenees), or to Prades, La Garrotxa, etc., although these are the result of moderate, natural acidification processes and only cover a limited area.
The deposition of atmospheric pollutants (sulphide dioxide SO2 and nitrogen oxides NOx), in the form of acid rain, accelerates the acidification process in acidic soils, although not in those that naturally contain calcium carbonate, which buffers the process. This is the case in many of the soils of Catalonia.
(acidic deposition).
Importance: Wetlands (udic soil moisture regime).
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