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| Nascimento,Lilian Rodrigues do; Sifeddine,Abdelfettah; Torgan,Lezilda Carvalho; Albuquerque,Ana Luiza Spadano. |
| The composition and spatial variation of diatom assemblage in surface sediments of Caçó Lake (shallow, mesotrophic and weakly acid lake - Maranhão State, Brazil) were analyzed in order to know the distribution pattern of the species along the lake during rainy season (April 1999). Four zones were established in the lake based on 21 diatoms species and habitat affinities. The first three zones (prime three meters deep to six meters deep) were marked by the occurrence of Pinnularia gigas, Frustulia rhomboides, Encyonopsis krasskei, Eunotia camelus, E. femoriformis and E. monodon. Zone IV (seven to nine meters deep) was inhabited mainly by Surirella biseriata and Fragilariforma floridana. During the beginning of the rainy season, the diatom assemblage in Caçó... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Diatoms; Shallow lake; Surface sediments; Caçó Lake; Brazil. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132010000100030 |
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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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| Zocatelli,Renata; Cecanho,Fernanda; Amorim,Marcelo; Bernardes,Marcelo; Moreira-Turcq,Patricia; Turcq,Bruno; Sifeddine,Abdelfettah; Cordeiro,Renato Campello. |
| Este estudo tem por objetivo caracterizar os sedimentos superficiais, quanto ao seu teor e qualidade dos fenóis da lignina, em dois sistemas lacustres distintos: a Várzea do Lago Grande Curuái (PA) e o Lago do Caçó (MA). A Várzea do Lago Grande Curuái é localizada na margem direita do Rio Amazonas, aproximadamente 850 km da foz e é caracterizada pela presença de lagos de águas brancas e pretas. O Lago do Caçó está localizado no Maranhão, na borda do ecossistema amazônico. Foram realizadas análises da concentração de lignina (λ), carbono orgânico total (COT), nitrogênio e isótopos do carbono (δ13C). Os resultados indicam que os sedimentos superficias de lagos de águas brancas apresentam baixos valores de COT (1,5 a 3,6%), baixa concentração de λ (0,73 a... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Matéria orgânica; Carbono; Isótopos estáveis e lignina. |
| Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672011000200003 |
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