Changes in optical properties caused by UV-irradiation of aquatic humic substances from the amazon river basin: Seasonal variability evaluation

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dc.contributor.authorRodriguez-Zuniga, Ursula Fabiola
dc.contributor.authorBastos Pereira Milori, Debora Marcondes
dc.contributor.authorLopes da Silva, Wilson Tadeu
dc.contributor.authorMartin-Neto, Ladislau
dc.contributor.authorOliveira, Luciana Camargo [UNESP]
dc.contributor.authorRocha, Julio Cesar [UNESP]
dc.contributor.institutionEmpresa Brasileira de Pesquisa Agropecuária (EMBRAPA)
dc.contributor.institutionUniversidade de São Paulo (USP)
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.date.accessioned2014-05-20T14:19:31Z
dc.date.available2014-05-20T14:19:31Z
dc.date.issued2008-03-15
dc.description.abstractAquatic humic substances (AHS) isolated from two characteristic seasons of the Negro river, winter and summer corresponding to floody and dry periods, were structurally characterized by (13)C nuclear magnetic ressonance. Subsequently, AHS aqueous solutions were irradiated with a polychromatic lamp (290-475 nm) and monitored by its total organic carbon (TOC) content, ultraviolet-visible (UV-vis) absorbance, fluorescence and Fourier transformed infrared spectroscopy (FTIR). As a result, a photobleaching upto 80% after irradiation of 48 h was observed. Conformational rearrangements and formation of low molecular complexity structures were formed during the irradiation, as deduced from the pH decrement and the fluorescence shifting to lower wavelengths. Additionally a significant mineralization with the formation of CO(2), CO, and inorganic carbon compounds was registered, as assumed by TOC losses of up to 70%. The differences in photodegradation between samples expressed by photobleaching efficiency were enhanced in the summer sample and related to its elevated aromatic content. Aromatic structures are assumed to have high autosensitization capacity effects mediated by the free radical generation from quinone and phenolic moieties.en
dc.description.affiliationEmpresa Brasileira de Pesquisa Agropecuária (EMBRAPA) Agr Instrumentat, BR-13560970 São Carlos, SP, Brazil
dc.description.affiliationUniv São Paulo, Inst Chem São Carlos, BR-13560970 São Carlos, SP, Brazil
dc.description.affiliationPaulista State Univ Julio Mesquista Filho, Inst Chem, BR-11780090 Araraquara, SP, Brazil
dc.description.affiliationUnespPaulista State Univ Julio Mesquista Filho, Inst Chem, BR-11780090 Araraquara, SP, Brazil
dc.format.extent1948-1953
dc.identifierhttp://dx.doi.org/10.1021/es702156n
dc.identifier.citationEnvironmental Science & Technology. Washington: Amer Chemical Soc, v. 42, n. 6, p. 1948-1953, 2008.
dc.identifier.doi10.1021/es702156n
dc.identifier.issn0013-936X
dc.identifier.lattes4148837403618207
dc.identifier.urihttp://hdl.handle.net/11449/25895
dc.identifier.wosWOS:000253947700026
dc.language.isoeng
dc.publisherAmer Chemical Soc
dc.relation.ispartofEnvironmental Science & Technology
dc.relation.ispartofjcr6.653
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.titleChanges in optical properties caused by UV-irradiation of aquatic humic substances from the amazon river basin: Seasonal variability evaluationen
dc.typeArtigo
dcterms.licensehttp://pubs.acs.org/page/policy/nih/index.html
dcterms.rightsHolderAmer Chemical Soc
unesp.author.lattes4148837403618207
unesp.campusUniversidade Estadual Paulista (Unesp), Instituto de Química, Araraquarapt

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Artigos - Química Analítica - IQ