Aquatic humus from an unpolluted Brazilian dark-brown stream: general characterization and size fractionation of bound heavy metals

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dc.contributor.authorRocha, J. C.
dc.contributor.authorde Sene, J. J.
dc.contributor.authordos Santos, A.
dc.contributor.authorToscano, IAS
dc.contributor.authorZara, L. F.
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionUniversidade de São Paulo (USP)
dc.date.accessioned2014-05-20T15:28:02Z
dc.date.available2014-05-20T15:28:02Z
dc.date.issued2000-01-01
dc.description.abstractThe main pool of dissolved organic carbon in tropical aquatic environments, notably in dark-coloured streams, is concentrated in humic substances (HS). Aquatic HS are large organic molecules formed by micro-biotic degradation of biopolymers and polymerization of smaller organic molecules. From an environmental point of view, the study of metal-humic interactions is often aimed at predicting the effect of aquatic HS on the bioavailability of heavy metal ions in the environment. In the present work the aquatic humic substances (HS) isolated from a dark-brown stream (located in an environmental protection area near Cubatao city in São Paulo-State, Brazil) by means of the collector XAD-8 were investigated. FTIR studies showed that the carboxylic carbons are probably the most important binding sites for Hg(II) ions within humic molecules. C-13-NMR and H-1-NMR studies of aquatic HS showed the presence of constituents with a high degree of aromaticity (40% of carbons) and small substitution. A special five-stage tangential-flow ultrafiltration device (UF) was used for size fractionation of the aquatic HS under study and for their metal species in the molecular size range 1-100 kDa (six fractions). The fractionation patterns showed that metal traces remaining in aquatic HS after their XAD-8 isolation have different distributions. Generally, the major percentage of traces of Mn, Cd and Ni (determined by ICP-AES) was preferably complexed by molecules with relatively high molecular size. Cu was bound by fractions with low molecular size and Co showed no preferential binding site in the various humic fractions. Moreover, the species formed between aquatic HS and Hg(II), prepared by spiking (determined by CVAAS), appeared to be concentrated in the relatively high molecular size fraction F-1 (> 100 kDa).en
dc.description.affiliationUNESP, Inst Chem, BR-14800900 Araraquara, SP, Brazil
dc.description.affiliationUSP, IQSC, Inst Chem, Sao Carlos, SP, Brazil
dc.description.affiliationUnespUNESP, Inst Chem, BR-14800900 Araraquara, SP, Brazil
dc.format.extent39-44
dc.identifierhttp://dx.doi.org/10.1039/a907671i
dc.identifier.citationJournal of Environmental Monitoring. Cambridge: Royal Soc Chemistry, v. 2, n. 1, p. 39-44, 2000.
dc.identifier.doi10.1039/a907671i
dc.identifier.issn1464-0325
dc.identifier.urihttp://hdl.handle.net/11449/37934
dc.identifier.wosWOS:000085065500010
dc.language.isoeng
dc.publisherRoyal Soc Chemistry
dc.relation.ispartofJournal of Environmental Monitoring
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.titleAquatic humus from an unpolluted Brazilian dark-brown stream: general characterization and size fractionation of bound heavy metalsen
dc.typeArtigo
dcterms.licensehttp://www.rsc.org/AboutUs/Copyright/LicencetoPublishforjournals.asp
dcterms.rightsHolderRoyal Soc Chemistry

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