The geochemistry of mercury in central Amazonian soils developed on the Alter-do-Chao formation of the lower Tapajos River Valley, Para state, Brazil

Détails

ID Serval
serval:BIB_4AEB40E2A8B1
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
The geochemistry of mercury in central Amazonian soils developed on the Alter-do-Chao formation of the lower Tapajos River Valley, Para state, Brazil
Périodique
Science of the Total Environment
Auteur⸱e⸱s
Roulet  M., Lucotte  M., Saint-Aubin  A., Tran  S., Rheault  I., Farella  N., De Jesus Da silva  E., Dezencourt  J., Sousa Passos  C. J., Santos Soares  G., Guimaraes  J. R., Mergler  D., Amorim  M.
ISSN
0048-9697 (Print)
Statut éditorial
Publié
Date de publication
11/1998
Volume
223
Numéro
1
Pages
1-24
Notes
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Nov 3
Résumé
In an oxisol-spodosol system developed on the terrestrial surface of the lower Tapajos Valley, the determination of total mercury (Hg), organic carbon (C), iron and aluminum oxy-hydroxide (Fe(cdb) and Al(cdb)) concentrations in the surface soil horizons are used to characterise the geochemical processes controlling the accumulation of Hg in soils under natural vegetation cover and in deforested and cultivated sites. Oxisols from the plateau have homogeneous and relatively high background Hg contents and burdens constituting an important natural reservoir of Hg for the region (90-210 ng/g dry wt. and 19-33 mg/m2 for the first 20 cm). The Fe(cdb) and Al(cdb) contents associated with the fine fraction (< 63 microns) of the soil suggest that oxy-hydroxides and, particularly Al-substituted Fe oxy-hydroxides, control the Hg concentrations observed in all of the soils of the study region. Consequently, the geochemistry of these minerals along the slopes governs the accumulation or the release of the Hg according to the natural evolution of the soil cover and/or following the degradation of soils by erosion after deforestation and cultivation. These observations have important implications for the interpretation of Hg contamination patterns observed in Amazonian aquatic systems that could be linked to different drainage sources of Hg from the terrestrial surface. The sandification and podzolisation that is characteristic of the evolution of numerous pedological systems in the equatorial Amazon could be responsible for exportation of the naturally accumulated Hg, as for other metals, by acidic complexation and migration to the black waters of the Amazon. In the central Amazon region, as a result of the fragility of the soil cover, deforestation and cultivation, affecting principally the superficial soil, promote the selective erosion of fine particles enriched in oxides and Hg. The erosion of soil could be responsible for an important release of Hg, transported in particulate form by drainage waters.
Mots-clé
Aluminum/chemistry Brazil Ecosystem Geologic Sediments Hydroxides Iron/chemistry Mercury/*analysis/chemistry Soil Pollutants/*analysis
Pubmed
Web of science
Création de la notice
24/01/2008 20:33
Dernière modification de la notice
20/08/2019 13:58
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