Spatio-temporal behaviour and mass balance of fluorine in forest soils near an aluminium smelting plant: short- and long-term aspects.
With the help of a large number of monitoring sites, the behaviour of F in forested ecosystems of a formerly polluted area (Möhlin and Rheinfelden, Switzerland) could be studied over 30 years. An aluminium smelting plant originated the pollution of this area in the past: however, after the installation of a filtration plant in 1958 the F emissions were reduced and since 1991 almost absent the primary production of aluminium was stopped. The present-day area with elevated F contents (water-soluble F with >20 mg/kg) is restricted to a radius of about 1000 m from the plant. In 1969 this area had a radius of about 3 and 5 km. Between 1969 and 2000 a significant decrease in the soluble F content in the soil was observed together with a substantial decrease of F in the vegetation. The net losses of water-soluble F in the soil were in the range of 35 up to more than 70% of the original concentration and the F losses in the vegetation between 60 up to more than 80%. After the reduction of high F deposition rates the accumulated SOM was decomposed within the observation period 1969-1993. The combined decrease in F and humus led to chain reactions with losses of major elements and a dealumination of clay minerals, i.e. removal of interlayered Al of 2:1 minerals and consequent formation of smectites.
Department of Geography, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland. megli@geo.unizch.ch
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D000535:Aluminum; D001673:Biodegradation, Environmental; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D004787:Environmental Pollution; D005461:Fluorine / Q000032:analysis*; D019015:Geologic Sediments / Q000737:chemistry; D008669:Metallurgy; D010944:Plants / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*; D013997:Time Factors; D014197:Trees
D012989:Soil Pollutants; D005461:Fluorine; D000535:Aluminum