Lichen (Parmotrema crinitum) prélevé à Rio de Janeiro
Téléchargez le pdf : ici.
L’article “Tracking atmospheric dispersion of metals in Rio de Janeiro Metropolitan region (Brazil) with epiphytes as bioindicators.” par Marques Jr., A.N., Paneto, D.P.; Lamego, F.; Nepomuceno, F.O.; Monna, F.; Losno, R.; Guillon, R. vient d’être publié dans Annals of the Brazilian Academy of Sciences. 90, 2991-3005.
La dispersion atmosphérique des polluants autour de Rio de Janeiro a été étudiée à l’aide de l’analyse de lichens appartenant l’espèce Parmotrema crinitum et de Broméliacées Tillandsia usneoides, aussi appelées mousses espagnoles, filles de l’air ou barbes du vieillard. Un gradient de pollution est mis en évidence grâce aux concentrations en éléments traces contenus dans ces organismes épiphytes et à la mesure des isotopes du plomb. Le schéma de dispersion est clairement associé au régime de circulation atmosphérique dans lequel, lors de l’arrivée des fronts froids, les masses d’air de la région métropolitaine de Rio de Janeiro sont acheminées vers la région montagneuse de Teresópolis, qui fait obstacle à la dissipation des polluants.
Abstract: The atmospheric dispersion atmospheric plume of the metropolitan region and neighborhoods of the city of Rio de Janeiro was investigated through elemental analyzes (Na, K, Al, Mn, Pb, Ni, Cr) and stable lead isotopes in two epiphytes; the lichen Parmotrema crinitum (Ach.) and the bromeliad Tillandsia usneoides (L.). All the elements had lower concentrations in epiphytes than in rocks of the local geological basement, with the exception of K, which was similar to rocks. This behavior was attributed to the nutritional essentiality and abundance of this element in the environment. The concentrations of Na, Pb and the 206Pb/207Pb and 208Pb/206Pb ratios indicated the presence of spatial gradients in the path (a) sea shore → continent, and (b) urban center → farmlands. These patterns were associated with the mesoscale atmospheric circulation regime, in which, during the arrival of cold fronts, air masses from the metropolitan region of Rio de Janeiro are transported towards the mountainous region of Teresópolis, which acts as a barrier to the dispersion of pollutants. The bromeliad Tillandsia usneoides and the lichen Parmotrema crinitum were linked to Na and Pb atmospheric levels, respectively.