HR: 08:45h
AN: B51F-04    [Abstracts]
TI: Trace Gas Fluxes From Through-Canopy Measurements in an Upland Forest of the Eastern Brazilian Amazon
AU: * Crill, P
EM: patrick.crill@geo.su.se
AF: Stockholm University, Department of Geology and Geochemistry, Stockholm, 106 91, Sweden
AU: * Crill, P
EM: patrick.crill@geo.su.se
AF: University of New Hampshire, Complex Systems Research Center, Durham, NH 03824, United States
AU: Keller, M
EM: michael.keller@unh.edu
AF: USDA Forest Service, International Institute of Tropical Forestry, San Juan, PR 00926, United States
AU: Keller, M
EM: michael.keller@unh.edu
AF: University of New Hampshire, Complex Systems Research Center, Durham, NH 03824, United States
AU: Silva, H
EM: hsilvaus@yahoo.com
AF: University of New Hampshire, Complex Systems Research Center, Durham, NH 03824, United States
AU: Silva, H
EM: hsilvaus@yahoo.com
AF: Universidade Federal do Para, em Santarem, Santarem, PA 68035, Brazil
AU: Dias, J D
EM: jadson@lbaeco.com.br
AF: Fundação Floresta Tropical, Rua Osvaldo Coelho, 64, Mapiri, Santarem, PA 68040-180, Brazil
AU: Albuquerque, S
EM: sergio@lbaeco.com.br
AF: Fundação Floresta Tropical, Rua Osvaldo Coelho, 64, Mapiri, Santarem, PA 68040-180, Brazil
AU: Czepiel, P
EM: peter.czepiel@unh.edu
AF: University of New Hampshire, Complex Systems Research Center, Durham, NH 03824, United States
AU: de Oliveira, R C
EM: cosme@cpatu.embrapa.br
AF: EMBRAPA Amazônia Oriental, Conjunto Medici I Rua Capanema 85 Bairro Marambaia, Belem, PA 66620-270, Brazil
AB: Methane (CH₄) is a radiatively active trace gas whose atmospheric budget has been perturbed by humans. Wetlands have been recognized as the main natural source of CH₄ for the past 30 years. Current inverse models indicate that tropical sources account for the bulk of CH₄ emissions. The largest sources are likely wetlands, agriculture and burning and that these sources may be underestimated. As part of the LBA experiment, we automatically sampled CH₄ and carbon dioxide (CO₂) mixing ratios in profiles through two forest canopies at sites 67 and 83 km south of Santarém, Pará. CH₄ and CO₂ can have a strong diurnal signal. CH₄ mixing ratios correlated well with CO₂. Both gases had column maxima in the early morning near dawn because of stable nocturnal conditions. However there were differences in the profiles. Highest CO₂ mixing ratios tended to occur near the surface due to the strong respiration source of CO₂. Often the lowest mixing ratios of CH₄ were found near the surface which is consistent with a weak soil sink. Calculations of the CH₄ flux of example periods from different seasons were made by correlating height weighted averages of the half hourly ambient mixing ratios of CH₄ and CO₂ and relating this correlation to the ratio of coincident nocturnal NEE CO₂ eddy correlation fluxes made during windy nights at two towers at the same sites and automated chamber flux measurements made at the km67 site. Fluxes were calculated to be between 2.2 and 23.3 mg CH₄ m^-2 d^-1. If the area of the upland forest area of the Amazon basin is 5 x 10⁶ km², we then estimate a CH₄ source strength of 4 to 43 Tg y^-1. This estimate is consistent with a flux of 4 to 38 Tg y^-1 calculated from a survey of profile and flux measurements made during the dry and wet seasons at three other sites across the Amazon basin.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0428 Carbon cycling (4806)
DE: 0490 Trace gases
SC: Biogeosciences [B]
MN: 2007 Fall Meeting