| Full text | |
| Author(s): |
Rodríguez-Zuniga, Ursula Fabiola
[1]
;
Milori, Débora Marcondes Bastos Pereira
;
Silva, Wilson Tadeu Lopes da
[3]
;
Martin-Neto, Ladislau
[4]
;
Oliveira, Luciana Camargo
[5]
;
Rocha, Julio Cesar
[6]
Total Authors: 6
|
| Affiliation: | [1] Brasil. Ministério da Agricultura, Pecuária e Abastecimento. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) - Brasil
[3] Brasil. Ministério da Agricultura, Pecuária e Abastecimento. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) - Brasil
[4] Brasil. Ministério da Agricultura, Pecuária e Abastecimento. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) - Brasil
[5] Universidade Estadual Paulista (UNESP). Campus de Araraquara. Instituto de Química - Brasil
[6] Universidade Estadual Paulista (UNESP). Campus de Araraquara. Instituto de Química - Brasil
Total Affiliations: 6
|
| Document type: | Journal article |
| Source: | Environmental Science & Technology; v. 42, n. 6, p. 1948-1953, 2008. |
| Field of knowledge: | Agronomical Sciences - Agronomy |
| Abstract | |
Aquatic 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 13C 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 up to 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 CO2, 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. (AU) | |
| FAPESP's process: | 98/14270-8 - Center for Optical and Photonics Science |
| Grantee: | Vanderlei Salvador Bagnato |
| Support Opportunities: | Research Grants - Research, Innovation and Dissemination Centers - RIDC |