2023-10-03 09:29:50
Phosphorus (P) is an essential trace element for flora and fauna. If on a global scale its dominant atmospheric source, the emission of terrigenous dust, is reasonably well known, in temperate and anthropized regions other sources become important such as the emission of particles by vegetation (mushroom spores, pollens) and by certain human activities (coal combustion, steel industry). With an uncertainty of more than an order of magnitude, these last two sources remain very poorly quantified. Reducing these uncertainties is all the more important as these sources emit phosphorus that is more easily bioavailable than that emitted with terrigenous dust.
Chemical analyzes in ice cores (phosphorus and source tracers) taken at Col du Dôme in the Alps were carried out to document and understand the evolution of P contents in Europe during the 20th century. These data were compared to deposition estimated by the FLEXPART aerosol dispersion model using statistical data on coal consumption and cast iron and steel production.
This unique study of phosphorus in ice carried out by a CNRS-INSU research team (see box), shows an increase of a factor of 2-3 in deposits between the pre-industrial period and the end of the 20th century. This increase results first of all from a recent increase in terrigenous emissions (Saharan contributions in particular) as evidenced by the increase in cerium. It was accompanied by an increase in emissions linked to the strong expansion of forests in France following 1960. Finally, the highly polluting emissions resulting from the combustion of coal and the steel industry also disrupted the phosphorus budget in the middle of the 20th century for decrease sharply in the 1980s following the installation of particle filters and desulfurization systems. Furthermore, these observations in the ice are in better agreement with the lower range of estimates of phosphorus emissions proposed in the literature for both vegetation and combustion.
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