Biogeochemistry of Carbon in the Amazonian Floodplains over a 2000-km Reach: Insights from a Process-Based Model

Earth Interactions

VincentBustillo¹ 

关键词: Amazon River;    Floodplains;    Biogeochemical cycles;    Carbon;    CO2 outgassing;   

DOI  :  10.1175/2010EI338.1

学科分类：地球科学(综合)

来源: American Geophysical Union

【 摘 要 】

Abstract The influence of Amazonian floodplains on the hydrological, sedimentary, and biogeochemical river budget was investigated over a 2000-km reach. A process-based model relying on the closure of chemical fluxes and isotopic signals was implemented. On average for the whole studied reach, the overall fluxes of carbon associated with mineralization and aquatic photosynthesis were estimated to 35.7 and 15.3 Tg C yr−1, respectively. Almost 57% of the carbon sequestrated by photosynthesis comes from aerial sources (flooded forest); the remaining 43% resulted from aquatic sources (várzea grasses and phytoplankton). The process rates substantially fluctuate over the annual cycle, depending particularly on the extension of flooded area and on the river–floodplain connectivity. As the river level declines, the drastic decrease of turbidity and the lower supply of carbon substrates promote autotrophy to the detriment of heterotrophy, leading to substantial changes of pH and gaseous equilibria in the river wat...

【 授权许可】

Unknown