An Integrated Approach to Tracking Paleohydrological Changes Along the Amazon Basin

The Amazon Basin is an important and arguably key component for modulating climate due to its role on the global atmospheric circulation and hydrological cycle, in addition to the carbon storage amenable to fast release to the atmosphere throughout land use change or drought-induced feedbacks. This basin encompass one of the largest wetlands in the world that covers 44% of the entire basin and contain thousands of lakes where large quantities of sedimentary organic matter can be stored. Amazonian paleoenvironmental and paleohydrological studies are critical to understand the current interactions between vegetation and hydrological dynamics and carbon balance, especially with respect to future climate behavior in a global warming scenario. During the Holocene paleohydrological studies in floodplain lakes in the Low and High Amazon Basin had also demonstrated a strong fluvial influence in these ecosystems, with significant impacts on the sedimentary process. In order to track past trends of Amazon River hydrological variations and its impacts on the floodplain lakes sedimentary process the aim of this study was to investigate the effectiveness of using an integrated approach of mineral and sedimentary organic composition to investigate changes in the Amazon River and the catchment basin input in lacustrine sediments. As the Amazon River sediment has a clay assemblage characterized by relatively high smectite content with low carbon concentration and the bedrock of the Terra Firme (i.e. unflooded upland) forms mainly kaolinite with elevated organic content a survey of floodplain sediments along the Amazon Basin was analyzed. Our results shows that the proportions of smectite and kaolinte and total carbon concentration correlate with the fluvial and terrestrial sedimentary input making this tool applicable to track water level changes of the Amazon River and its tributaries at different temporal scales