8 documents found, page 1 of 1
Interaction of Pb, Ni and Cd with aquatic humic substances of amazonian blackwa...
Constantino, Isabela C. [UNESP]; Viana, Juliana G. [UNESP]; Teixeira, Priscila A. [UNESP]; Moreira, Altair B. [UNESP]; Gama, Giovanna P.Made available in DSpace on 2021-06-25T10:49:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-02-01. Added 1 bitstream(s) on 2021-07-15T15:05:11Z : No. of bitstreams: 1 S0103-50532021000200260.pdf: 2266020 bytes, checksum: 3eb8d996686eb3701a6245d12c8c2ba7 (MD5); In this study, the extraction and characterization of aquatic humic substances (AHS) from two blackwater rivers in the Amazon basin was carrie...
Extraction of aquatic organic matter by temperature decreasing: An alternative ...
Almeida, Rosana N. H. Martins de; Mozeto, Antonio Aparecido; Zara, Luiz Fabrício; Rosa, André Henrique; Rocha, Júlio César; Rom?o, Luciane Pimenta CruzIn this work was developed an alternative methodology to separation of aquatic organic matter (AOM) present in natural river waters. The process is based in temperature decreasing of the aqueous sample under controlled conditions that provoke the freezing of the sample and separation of the dark extract, not frozen and rich in organic matter. The results showed that speed of temperature decreasing exerts strong...
Seasonal behavior of mercury species in waters and sediments from the Negro Riv...
Bisinoti, Márcia Cristina; Sargentini, Ézio; Jardim, Wilson de FigueiredoTotal (HgT), reactive (HgR) and organic (Hg ORG) mercury species have been quantified in non-filtered waters collected from the Negro River Basin, Amazon (from January/2002 through January/2004), in both black and white water bodies. Black waters presented the highest HgT, HgORG and HgR concentration (29.1 ng L-1, 1.63 ng L-1 and 3.9 ng L-1, respectively), while, white waters presented the lowest HgT, Hg ORG an...
Multi-method Study on Aquatic Humic Substances from the "Rio Negro" - Amazonas ...
Rocha, Júlio César; Sargentini, Ézio; Toscano, Ilda Antonieta Salata; Rosa, André Henrique; Burba, PeterThe aquatic humic substances investigated in this study were conventionally isolated from Rio Negro waters - Amazonas State/Brazil by means of the collector XAD 8. Molecular spectroscopy investigations of these humic substances using 1H-NMR and 13C-NMR indicated the presence of high aromaticity with few substituents, small amounts of carboxylic carbon, and an aliphatic/aromatic ratio of 1:1. The relatively high...
The influence of seasonalness on the structural characteristics of aquatic humi...
Oliveira, L. C.; Sargentini, Ézio; Rosa, André Henrique; Rocha, Júlio César; Simões, Marcelo Luiz; Martin-Neto, Ladislau; Silva, Wilson Tadeu Lopes daIn this work, humic substances were extracted from water samples collected monthly from the Negro River basin in the Amazon state (Brazil) to study their properties in the Amazonian environment and interactions with the mercury ion considering the influence of seasonalness in this formation. The C/H, C/N and C/O atomic ratio parameters, functional groups, concentration of semiquinone-type free radicals, pH, plu...
Influence of seasonality on the interaction of mercury with aquatic humic subst...
Oliveira, L. C.; Botero, Wander Gustavo; Santos, Felipe André dos; Sargentini, Ézio; Rocha, Júlio César; dos Santos, Ademir BernardoHigh mercury concentrations in different environmental matrices in the Amazon have been attributed to mining activities. However, high concentrations of mercury are also present in the soil and water in places like in the middle of the Negro River Basin, which is far away from any anthropogenic emission sources. The Amazon region is characterized by two different regional seasons, with well-defined flood and lo...
Nanoscaled hydrated antimony (V) oxide as a new approach to first-line antileis...
Franco, A. M.; Grafova, Iryna A.; Soares, Fabiane Veloso; Gentile, Gennaro; Wyrepkowski, Claudia D C; Bolson, Marcos A.; Sargentini, ÉzioBackground: Coordination compounds of pentavalent antimony have been, and remain, the first-line drugs in leishmaniasis treatment for >70 years. Molecular forms of Sb (V) complexes are commercialized as sodium stibogluconate (Pentostam®) and meglumine antimoniate (MA) (Glucantime®). Ever-increasing drug resistance in the parasites limits the use of antimonials, due to the low drug concentrations being administe...
Humic substances: A sequential device for fractionation by ultrafiltration with...
Rocha, Júlio César; Zara, Luiz Fabrício; Rosa, André Henrique; Sargentini, Ézio; Burba, PeterA sequential system for fractionation by ultrafiltration (SSFU) equipped with advanced membranes filters (molecular size cut-off: 5, 10, 30, 50 and 100 kDalton) of the polyethersulfone type was developed for analytical fractionation of humic substances (HS) extracted from aquatic systems or soils. The device consists of five membrane filters (Sartocon® Micro) operated by a multi-channel peristaltic pump, enabli...