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| Tavares,Claudinéia R.O.; Bendassolli,José A.; Coelho,Fernando; Sant'ana Filho,Carlos R.; Prestes,Clelber V.. |
| This work describes a method for 15N-isotope-labeled glycine synthesis, as well as details about a recovery line for nitrogen residues. To that effect, amination of alpha-haloacids was performed, using carboxylic chloroacetic acid and labeled aqueous ammonia (15NH3). Special care was taken to avoid possible 15NH3 losses, since its production cost is high. In that respect, although the purchase cost of the 13N-labeled compound (radioactive) is lower, the stable tracer produced constitutes an important tool for N cycling studies in living organisms, also minimizing labor and environmental hazards, as well as time limitation problems in field studies. The tests were carried out with three replications, and variable 15NH3(aq) volumes in the reaction were used... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Stable isotope; Glycine; Amino acid. |
| Ano: 2006 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652006000300005 |
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| Pessenda,Luiz C.R.; Gouveia,Susy E.M.; Ledru,Marie-Pierre; Aravena,Ramon; Ricardi-Branco,Fresia S.; Bendassolli,José A.; Ribeiro,Adauto de S.; Saia,Soraya E.M.G.; Sifeddine,Abdelfettah; Menor,Eldemar de A.; Oliveira,Sônia M.B. de; Cordeiro,Renato C.; Freitas,Ângela M. de M.; Boulet,René; Filizola,Heloisa F.. |
| The aim of this research was to reconstruct vegetation changes (with climate inferences) that occurred during the Holocene in the Fernando de Noronha Island, Pernambuco State, northeastern Brazil. The research approach included the use of geochemical (mineralogy, elemental), carbon isotopes (δ13C, 14C) and pollen analyses in soil organic matter (SOM) and sediments collected in Lagoa da Viração and Manguezal do Sueste. The carbon isotopes data of SOM indicated that there was no significant vegetation changes during the last 7400 BP, suggesting that the climate was not the determinant factor for the vegetation dynamics. The pollen analysis of the sediment of a core collected in the Lagoa da Viração showed the absence of Quaternary material in the period... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Pollen; Carbon isotopes; Paleovegetation; Fernando de Noronha; Holocene. |
| Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652008000400009 |
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| Pessenda,Luiz C.R.; Saia,Soraya E.M.G.; Gouveia,Susy E.M.; Ledru,Marie-Pierre; Sifeddine,Abdelfettah; Amaral,Paula G.C.; Bendassolli,José A.. |
| This study presents paleoenvironmental data based on pollen, elemental and isotopic compositions of organic matter (TOC, N, d13C and d15N) and 14C dating of 170 cm lake sediment record. Samplings have been made in Lagoa Grande at Parque Estadual Turístico do Alto Ribeira - PETAR, Southern São Paulo State, Southeastern Brazil. The variations in relative frequencies (in percentage) of arboreal pollen along the core range between 40 and 80%. The d13C values ranged from -23 to -30 and C/N of ~10 to 15, indicating the contribution of terrestrial C3 plants and algae in the sediment organic matter. The d15N results presented values from 3 to 4.5, also suggesting a mixture of algae and terrestrial C3 plants. The 14C dating indicates modern age for the shallow... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Lacustrine sediment; C and N isotopes; Pollen; Atlantic Forest; Last millennium; Little Ice Age. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652010000300019 |
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