Cinética e variação molecular de substâncias húmicas formadas da lixiviação de macrófitas aquáticas

• Ano de defesa: 2015
• Autor(a) principal: Assunção, Argos Willian de Almeida
• Orientador(a): Bianchini Júnior, Irineu
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Carlos; Câmpus São Carlos
• Programa de Pós-Graduação: Programa de Pós-Graduação em Ecologia e Recursos Naturais - PPGERN
• Palavras-chave em Português: Limnologia; Ácido fúlvico; Ácido húmico; Carbono orgânico dissolvido; Disponibilidade de oxigênio; Modelagem matemática
• Palavras-chave em Inglês: Fulvic acids; Humic acids; Dissolved organic carbon; Mathematical modeling; Oxygen availability
• Área do conhecimento CNPq: CIENCIAS BIOLOGICAS::ECOLOGIA
• Link de acesso: https://repositorio.ufscar.br/handle/20.500.14289/7128

The humic substances (HS) are important to aquatic ecosystems. In this study we investigated the kinetics and molecular variations of dissolved fulvic acids (FA) and humic acids (HA) formed from aquatic macrophytes decomposition under aerobic and anaerobic conditions. The results supported the proposition and validation of kinetic models that treated the formation, transformation and mineralization of dissolved SH. Although mineralization and humification are concurrent events, the aerobic condition favored these two processes contributed primarily to HA formation. The detritus showed different mineralization and HS formation potentials. Larger amounts of HS were related to higher carbon content in the detritus and lower mineralization of dissolved organic carbon (DOC). The SH mass loss rates were lower than the refractory fraction of particulate detritus, showing the recalcitrance of dissolved HS. The DOC with higher C/N proportions presented higher coefficient rates. The HS presented similar characteristics regardless of detritus source. However, aerobic conditions favored variation of polysaccharides content in HS, indicating transformation of these compounds. Aerobic conditions favored dissolved HS mineralization and its assimilation by microorganisms. The AH presented higher reactive fraction than FA, and was an important precursor of FA. The FA presented refractory characteristics and formed less HA, indicating that the liginocellulosic compounds of the detritus are the main precursors of HA.