Methane emission by ebullitive transport was detected only in about 40% of the measurements, but it contributed 90% to total methane release to the atmosphere in the southern Pantanal region, so confirming the early results presented by Marani and Alvala (2007). Although a correlation between the fluxes and the environmental parameters was very weak, the diffusive transport events presented a statistically significant difference between the wet and dry seasons, however, the ebullitive fluxes did not present statistically significant differences between the wet and dry seasons, while the environmental parameters showed statistically significant differences between the two seasons. The severe drought that the region was subjected to during two years of the study may have influenced the flooding and the emission patterns. The methane emission estimates using different approximations, since a simplified general average flux, up to considering the diffusive, ebullitive and vegetation influences, resulted in methane release to atmosphere in the range of 1.4-2.2 Tg CH4 y-1, corresponding to about 2.2% of the global emission from natural wetlands. Thus, Pantanal may have the same potential of emission as Amazonia. Finally, additional areas of the Pantanal should be investigated to increase the confidence in the emission pattern obtained in this study.
Acknowledgments We thank Dr. Ralf Gielow for suggestions and the revision that improved the manuscript, the UFMS (Federal University of Matogrosso do Sul) for the logistical support, the Laboratorio de Ozonio staff for the cooperation and facilities support, and INPE (National Space Research Institute of Brazil) and CNPq (projeto 474816/03-6) for financial support.
Alvala PC, Kirchhoff VWJH (2000) Methane fluxes from the Pantanal floodplain in Brazil: seasonal variation. In: J van Ham et al. (ed) Non-CO2 Greenhouse Gases: Scientific Understanding, Control and Implementation, Kluwer Academic Publishers, Dordrecht, pp 95-99 Bartlett KB, Crill PM, Bonassi JA, Richey JE, Harriss RC (1990) Methane flux from the Amazon
River floodplain: emissions during the rising water. J Geophys Res 95:16773-16788 Bartlett KB, Crill PM, Sebacher DI, Harris RC, Wilson JO, Melack JM (1988) Methane flux from the central Amazonian floodplain. J Geophys Res 93:1571-1582 Bartlett KB, Harriss RC (1993) Review and assessment of methane emission from wetlands. Chemosphere 26:1-4
Bastviken D, Cole J, Pace M, Tranvik L (2004) Methane emissions from lakes: dependence of lake characteristics, two regional assessments, and global estimate. Global Biogeochem Cycles 18 Blake DR, Rowland FS (1988) Continuing worldwide increase in tropospheric methane, 1978 to
1987. Science 239:1129-1131 Cicerone RJ, Delwiche CC, Tyler SC, Zimmerman PR (1992) Methane emission from California rice paddies with varied treatments. Global Biogeochem Cycles 6(3):233-248 Christensen TR, Panikov N, Mastepanov M, Joabsson A, Steward A, O'quist M, Sommerkorn M, Reynaud S, Svensson B (2003) Biotic controls on CO2 and CH4 exchange in wetlands - A closed environment study. Biogeochemistry 64:337-354 Devol AH, Richey JE, Clark WA, King SL, Martinelli LA (1988) Methane emissions to the troposphere from the Amazon floodplain. J Geophys Res 93(D2):1583-1592
Devol AH, Richey JE, Forsberg BR, Martinelli LA (1990) Seasonal dynamics in methane emissions from the Amazon River floodplain to the troposphere. J Geophys Res 95(D10):16417-16426
Dlugokencky EJ, Dutton EG, Novelli PC, Tans PP, Masarie KA, Lantz KO, Madronich S (1996) Changes in CH4 and CO growth rates after the eruption of Mt. Pinatubo and their link with changes in tropical troposphere UV flux. Geophys Res Lett 23(20):2761-2764 Dlugokencky EJ, Masarie K, Lang P, Tans PP (1998) Continuing decline in the growth rate of the atmospheric methane burden. Nature 393:447-450 EMBRAPA (Empresa Brasileira de Pesquisa Agropecuaria) (2006) Cheia e seca no Pantanal,
<http://www.cpap.embrapa.br/destaques/cheia.htm>, (online) Etheridge D, Steele L, Francey R, Langenfelds R (1998) Atmospheric methane between 1000 A.D. and present: evidence of anthropogenic emissions and climatic variability. J Geophys Res 103:15979-15993
Hamilton SK, Sippel SJ, Melack JM (2002) Comparison of inundation patterns among major South
American floodplains. J Geophys Res 107(D20):1-14 Keller M, Stallard RF (1994) Methane emission by bubbling from Gatun Lake, Panama. J Geophys Res 99(D4):8307-8319
Lehner B, P Doll (2004) Development and validation of a global database of lakes, reservoirs and wetlands. J Hydrol 296(1-4):1-22 Marani L, Alvala PC (2007) Methane emissions from lakes and floodplains in Pantanal, Brazil.
Atmos Environ 41(8):1627-1633 Melack JM, Hess LL, Gastil M, Forsberg BR, Hamilton SK, Lima IBT, Novo EMLM (2004) Regionalization of methane emissions in the Amazon Basin with microwave remote sensing. Global Change Biol 10:530-544 Sass RL, Fisher FM, Wang YB, Turner FT, Jund MF (1992) Methane emissions from rice fields:
the effect of floodwater management. Global Biogeochem Cycles 6(3):249-262 Schiller CL, Hastie DR (1994) Exchange of nitrous-oxide within the Hudson-Bay lowland. J
Geophys Res 99:1573-1588 Smith LK, Lewis Jr. WM, Chanton JP, Cronin G, Hamilton SK (2002) Methane emission from the
Orinoco River floodplain, Venezuela. Biogeochemistry 51(2):113-140 Stern D, Kaufmann R (1996) Estimates of global anthropogenic methane emissions 1860-1993.
Chemosphere 33(1):159-176 Walter BP, Heimann M, Matthews E (2001) Modeling modern methane emissions from natural wetlands 2. Interannual variations 1982-1993. J Geophys Res 106:34207-34219 Wuebbles DJ, Hayhoe K (2002) Atmospheric methane and global change. Earth-Sci Rev 57:177210
Yang SS, Chang HL (1998) Effect of environmental conditions on methane production and emission from paddy soil. Agric Ecosys Environ 69(1):69-80
Was this article helpful?