The distribution of seasonally flooded areas in lowland Amazonia during the Holocene

• Grant number: 23/15362-7
• Support Opportunities: Scholarships in Brazil - Doctorate
• Effective date (Start): March 01, 2024
• Effective date (End): February 28, 2027
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Dailson José Bertassoli Junior
• Grantee: Dayane Batista Melo
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 22/06440-1 - Wetland expansion in Amazonia during the late Holocene and its implications to the global methane budget, AP.GR

Abstract

Freshwater wetlands are the single largest natural source of methane (CH4) to the atmosphere. Amazonian floodplains alone correspond to roughly one-fourth of global wetland emissions, but its impact to abrupt variations in the global CH4 budget remain under-explored. The abundance and relative concentration of soil-sourced bacteriohopanepolyols (BHPs) in sediment records has been successfully employed to reconstruct variations in the extent of wetlands in terrestrial environments. The application of this technique in sediment cores retrieved from marine areas under the influence of the Amazon River Plume will help to trace variations in methane-producing land cover in the Amazon Basin. In parallel, we will apply optically stimulated luminescence methods to provide ages for the stabilization of the sedimentary substrate of river islands and marginal floodplains. The obtained ages will be used to determine the chronology of floodplains formation and sediment aggradation within the Amazon River valley and in valleys of its large tributaries. The proposed dual approach using floodplains sedimentation chronology and lipid biomarkers in marine sediments will cross-validate our reconstructions. It will also allow us to provide a broad and integrated perspective of floodplains evolution and associated potential CH4 emissions during the Holocene.