Made available in DSpace on 2014-12-17T14:33:06Z (GMT). No. of bitstreams: 1 CarolineGBM_DISSERT.pdf: 778935 bytes, checksum: 2a19b59e3c8f14ceef97a9f6a966da73 (MD5) Previous issue date: 2010-02-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / O aumento da concentra??o de CO2 na atmosfera tem sido observado, principalmente a partir da revolu??o industrial. Uma das causas principais desse comportamento tem sido a queima de combust?veis f?sseis. Isso tem levado a altera??es globais no ciclo do carbono. Desta forma tem sido de suma import?ncia trabalhos que mostrem a influ?ncia dos sistemas em geral e suas contribui??es relativas na din?mica e ciclo do carbono. Dentro deste contexto, os ecossistemas aqu?ticos apresentam import?ncia no processamento da mat?ria org?nica produzida internamente nos sistemas aqu?ticos (aut?ctone), bem como a mat?ria org?nica trazida dos sistemas terrestres (al?ctone). Os principais organismos que metabolizam a mat?ria org?nica dissolvida (carbono org?nico dissolvido COD) presente nos sistemas aqu?ticos s?o as bact?rias. No entanto a qualidade da mat?ria org?nica determina a prefer?ncia e a via metab?lica (produ??o bacteriana - PB ou respira??o bacteriana - RB) pela qual o carbono ser? direcionado quando assimilado pelas bact?rias. Nos sistemas aqu?ticos a diversidade da mat?ria org?nica presente, muitas vezes estimula a produ??o bacteriana. Desta forma, os objetivos deste trabalho foram avaliar os efeitos do COD al?ctone e aut?ctone na PB e RB, al?m de avaliar o efeito da mistura de COD sobre o balan?o de CO2 no experimento de mesocosmo. Para testar os objetivos realizamos um experimento de mesocosmo com o arranjo experimental do tipo (2x2) destinado a simular condi??es onde houvesse o predom?nio de mat?ria org?nica aut?ctone (fitopl?ncton), al?ctone (detrito de vegeta??o terrestre) e ambas combinadas. Consistindo em quatro tratamentos incluindo o Controle. A dura??o do experimento foi de 42 dias. Verificamos no geral que os tratamentos enriquecidos com mat?ria org?nica al?ctone apresentaram as maiores taxas metab?licas (RB, CO2), o que provavelmente esteve relacionado ? qualidade da mat?ria org?nica utilizada. Conclu?mos que o aporte de mat?ria org?nica de origem terrestre resulta em aumento da atividade de decomposi??o resultando na condi??o de heterotrofia nos tanques estudados. Conclu?mos ainda que com o esgotamento da mat?ria, os tanques passaram a apresentarem-se subsaturados em CO2, resultando na condi??o de autotrofia. Conclu?mos tamb?m que nos tanques com mistura de fonte o efeito observado foi antag?nico. / The increased concentration of CO2 in the atmosphere has been observed, mainly from the industrial revolution. One of the main causes of this behavior has been the burning of fossil fuels. This has led to changes in the global carbon cycle. Thus it has been extremely important work showing the influence of systems in general and their contributions on the dynamics and the carbon cycle. Within this context, aquatic ecosystems have importance in the processing of domestically produced organic matter in aquatic systems (indigenous) and the organic matter brought from the terrestrial (allochthonous). The main organisms that metabolize dissolved organic matter (dissolved organic carbon - DOC) present in aquatic systems is bacteria. However the quality of organic matter determines the preference and the metabolic pathway (bacterial production - PB or bacterial respiration - RB) by which carbon will be directed when assimilated by bacteria. In aquatic systems, the diversity of organic matter present, often stimulates bacterial production. Thus, the objectives were to evaluate the effects of allochthonous and autochthonous DOC in the PB and RB, and to evaluate the effect of mixing of DOC on the CO2 balance in the mesocosm experiment. For testing purposes we conducted a mesocosm experiment with the experimental arrangement of type (2x2) to simulate conditions where there was a predominance of autochthonous organic matter (phytoplankton), allochthonous (terrestrial vegetation detritus) and both combined. Consisting of four treatments including control. The experiment lasted 42 days. We note that in general the treatments enriched with allochthonous organic matter showed the highest metabolic rates (RB, CO2), which probably was related to the quality of organic matter used. We conclude that the input of organic matter from terrestrial origin results in increased activity of decomposition resulting in the condition of heterotrophy in the tanks studied. We also concluded that the exhaustion of matter, the tanks began to present themselves in subsaturados CO2, resulting in the condition of autotrophy. We also conclude that the tanks blend with the source of the observed effect was antagonistic.