| 1. |
- Sanders, Luciana M., et al.
(författare)
-
Carbon accumulation in Amazonian floodplain lakes : A significant component of Amazon budgets?
- 2017
-
Ingår i: Limnology and Oceanography Letters. - : Wiley. - 2378-2242. ; 2:1, s. 29-35
-
Tidskriftsartikel (refereegranskat)abstract
- 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 Pb-210 derived sedimentation rates from four recently analyzed sediment cores (n = 4) with previously published organic carbon (OC) burial estimates (n = 18) to provide a broad, first order estimate of carbon accumulation in Amazon floodplain lakes. The OC burial rates were 266 +/- 57 g C m(-2) yr(-1). 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.
|
|
| 2. |
- Sanders, Luciana M., et al.
(författare)
-
Pu240+239 DEPOSITIONAL SIGNATURES AS A VIABLE GEOCHRONOLOGICAL TOOL IN THE AMAZON BASIN
- 2017
-
Ingår i: Geochronometria. - : DE GRUYTER OPEN LTD. - 1733-8387 .- 1897-1695. ; 44:1, s. 142-149
-
Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic radionuclide signatures associated with nuclear testing are increasingly utilized in environmental science to explore recent sedimentation. In this study, we assess the suitability of Pu radioisotope analysis in floodplain lake environments in the Amazon Basin to form geochronologies during the 20th century. The Pu-240 + Pu-239 (Pu240+239) signatures in six sediment cores indicate sediment accumulation rates in the floodplain lakes of the major rivers; Amazon (2.3 mm year(-1)), Tapajos (10.2 and 2.4 mm year(-1)) and Madeira (3.4, 4.2 and 6.2 mm year(-1)). The results from this study show that Pu240+239 fallout activities, and the well documented (Pu-240/Pu-239) atomic ratios of the above ground nuclear tests which began in the 1950s, are sufficient and well preserved in Amazon flood-plain lake sediments to infer chronologies. Lead-210 dating analyses in the same sediment cores produced comparable sediment accumulation rates at three of the six sites. The differences between dating methods may be attributed to the different time scale these dating methods represent and/or in the solubility between Pb and Pu along the sediment column. The geochronologies derived from the Pu240+239 and Pb-210 methods outlined in this work are of interest to identify the effects of changing sediment accumulation rates during the previous century as a result of development, including deforestation, along the Amazon Basin which increased towards the middle of the 20th century. This study shows that Pu dating provides a viable alternative geochronology tool for recent sediment accumulation (previous similar to 60 years) along the Amazon Basin.
|
|
