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Nature and properties of suspended solids in the Amazon Basin

Thierry Allard, Marie Ponthieu, Tiphaine Weber, Naziano Filizola, Jean-Loup Guyot and Marc Benedetti
Nature and properties of suspended solids in the Amazon Basin
Bulletin de la Societe Geologique de France (2002) 173 (1): 67-75


Suspended solids from several rivers of the Amazon Basin (Brazil) have been studied in both the particulate (>0,2 mu m) and colloidal (0.2 mu m-5 kD) fractions through a combination of tools including Fourier transform infrared spectroscopy (FT-IR), electron paramagnetic resonance (EPR) and potentiometric measurements. Particulate and colloidal matter are organo-mineral and organic, respectively. Signatures of the particulate fractions distinguish Rio Amazonas/Rio Solimoes rivers and the northern basin rivers (Rio Negro, Rio Branco, Rio Trombetas). In the latter, kaolinites are the dominant clays and exhibit close crystal chemistry characters such as degree of disorder. FT-IR of colloids exhibits similar signatures of humic substances in all rivers. By contrast, EPR reveals various species which qualitatively and quantitatively differentiate the riverborne colloids: trivalent iron occurring as specific complexes with organic functional groups or as oxides sensu lato, divalent manganese, organic free radicals. The observed differences may be inherited from the weathering processes working in the main pedoclimatic regions drained by the studied rivers. Insights from potentiometric measurements of the recovered colloids also evidence a humic like reactivity consistent with carboxyl and phenol moieties, the relative contributions of which differentiate the Rio Negro and Rio Solimoes/Amazonas.

ISSN: 0037-9409
EISSN: 1777-5817
Serial Title: Bulletin de la Societe Geologique de France
Serial Volume: 173
Serial Issue: 1
Title: Nature and properties of suspended solids in the Amazon Basin
Affiliation: Universites de Paris VI et VII, Laboratoire de Mineralogie-Cristallographie, Paris, France
Pages: 67-75
Published: 2002
Text Language: English
Summary Language: French
Publisher: Societe Geologique de France, Paris, France
References: 41
Accession Number: 2003-035187
Categories: Hydrogeology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: INSU Contrib. No. 301
Illustration Description: illus. incl. 1 table, geol. sketch map
S04°30'00" - N01°00'00", W73°30'00" - W49°30'00"
S06°30'00" - S02°00'00", W72°30'00" - W62°00'00"
Secondary Affiliation: ANEEL, BRA, BrazilUniversite Paul Sabatier, FRA, France
Country of Publication: France
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute.
Update Code: 200311
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