Carbon dioxide and methane emissions from interfluvial wetlands in the upper Negro River basin, Brazil
Carbon dioxide and methane emissions from interfluvial wetlands in the upper Negro River basin, Brazil
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DOI：
10.1007/s10533-010-9536-0
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发表时间：
2011-09-01
期刊：
影响因子：
4
通讯作者：
Melack, John M.
中科院分区：
文献类型：
--
作者：
Belger, Lauren;Forsberg, Bruce R.;Melack, John M.
广泛的河流间湿地出现在内格罗河上游流域（巴西），包含以涌现的草和莎草为主的植被马赛克，以及灌木和棕榈树的斑块。为了描述这些栖息地的二氧化碳和甲烷的释放特征，2005年在永久和季节性洪水地区每月测量了扩散和起泡排放以及通过植物通气组织的运输。二氧化碳排放量平均为每天2193毫克立方米（-2）。未淹水环境下消耗的甲烷和淹水环境下排放的甲烷的平均值分别为-4.8和60 mg cm (-2) d（-1）。气泡主要是在沉积物-水界面静水压力下降的落水期产生的。CO2和CH4的排放量随着溶解O-2的减少和植被的丰富而增加。通过合成孔径雷达和光学遥感数据的分析，确定了内格罗河南北两个湿地的总面积和季节变化的淹没面积。这两个湿地的总面积（3000 km(2)）以CO2形式排放了1147 Gg C年（-1），以CH4形式排放了31 Gg C年（-1）。如果将这些速率外推到内格罗盆地上游水态土壤所占的面积，则估计区域向大气逃逸的CO2为63 Tg C年（-1），CH4为1.7 Tg C年（-1）。
Extensive interfluvial wetlands occur in the upper Negro River basin (Brazil) and contain a mosaic of vegetation dominated by emergent grasses and sedges with patches of shrubs and palms. To characterize the release of carbon dioxide and methane from these habitats, diffusive and ebullitive emissions and transport through plant aerenchyma were measured monthly during 2005 in permanently and seasonally flooded areas. CO2 emissions averaged 2193 mg C m(-2) day(-1). Methane was consumed in unflooded environments and emitted in flooded environments with average values of -4.8 and 60 mg C m(-2) day(-1), respectively. Bubbles were emitted primarily during falling water periods when hydrostatic pressure at the sediment-water interface declined. CO2 and CH4 emissions increased when dissolved O-2 decreased and vegetation was more abundant. Total area and seasonally varying flooded areas for two wetlands, located north and south of the Negro River, were determined through analysis of synthetic aperture radar and optical remotely sensed data. The combined areas of these two wetlands (3000 km(2)) emitted 1147 Gg C year(-1) as CO2 and 31 Gg C year(-1) as CH4. If these rates are extrapolated to the area occupied by hydromorphic soils in the upper Negro basin, 63 Tg C year(-1) of CO2 and 1.7 Tg C year(-1) as CH4 are estimated as the regional evasion to the atmosphere.