01586naa a2200253 a 450000100080000000500110000800800410001910000200006024500760008026000090015652008930016565000140105865000130107265000100108565000100109565000130110565000150111865300130113365300150114665300120116170000180117370000180119177301230120917838152017-04-06       1994    bl ---       0--  u    #d1 aHAMILTON, S. K.  aThe origin of "excess CO2" in waters of the Pantanal wetland of Brazil.  c1994  aThe waters of the Pantanal, a large savanna floodplain, are characteristically low in dissolved O2 and high in dissolved CO2 and CH4. Analysis of dissolved gases in samples from throughout the region reveals that the waters tend to contain considerably more CO2 than can be accounted for by the observed consumption of dissolved O2. This "excess CO2" has several possible origins, including 1) anaerobic respiration or methanogenesis carried out by bacteria, 2) anaerobic metabolism in submerged organs of aquatic vascular plants, and 3) a greater tendency for dissolution of CO2 than O2 from the aerenchyma of submerged vascular plants. These alternative hypotheses are evaluated, drawing on additional measurements of the gas composition of sediment bubbles and plant stems. We conclude that the metabolism of emergent vascular plants is likely to be a major source of the "excess CO2".  alimnology  aPantanal  awater  aÁgua  aAnálise  aLimnologia  aAnalysis  aExcess CO2  aWetland1 aSIPPEL, S. J.1 aMELACK, J. M.  tIn: SYMPOSIUM ON THE BIOGEOCHEMISTRY OF WETLANDS, 3., 1994, Orlando. Abstracts... Orlando: [s.n.] 1994. não paginado.