Carbon accumulation in Amazonian floodplain lakes: a significant component of Amazon budgets?

The Amazon floodplains cover approximately 10% of the Amazon Basin and are composed of predominantly anoxic sediments that may store large amounts of carbon. Our study combines 210 Pb derived sedimentation rates from four recently analyzed sediment cores (n 5 4) with previously published organic carbon (OC) burial estimates (n 5 18) to provide a broad, first order estimate of carbon accumulation in Amazon floodplain lakes. The OC burial rates were 266 6 57 g C m 22 yr 21 . This rate is several folds greater than those reported for lakes in arctic, boreal, temperate, and tropical regions. The large amount and spatial variation of OC burial rates in these floodplain lakes highlights the need for increased sampling efforts to better measure these potentially important components of the Amazon Basin carbon budget.