SOG

The oligotrophic gyres occupy >40% of the Earth’s surface; thus, even relatively low carbon exports in these immense ocean provinces may significantly contribute to the global carbon budget. While surface ocean biology is very similar between two Atlantic central gyres, there is an established spatio-temporal variability in their upper ocean biogeochemistry. Presence of such a signature in the deep ocean has long been unknown due to a lack of direct measurements. A unique set of sediment trap samples was collected in the centres of the South and North Atlantic oligotrophic gyres at 3000m depth during 2007-2010. These extraordinary locations are on the annually repeated Atlantic Meridional Transect (AMT) line providing spatial context. Examination of trap material showed large inter-basin differences in downward particle flux and material composition, showing that biogeochemical differences translate into different export and sequestration scenarios, despite the similarity in surface ocean biology. With the predicted expansion of the oligotrophic oceans, such differences in carbon sequestration fluxes introduce a new perspective on the critical role of nutrient-limited waters in global carbon cycle and sinks of atmospheric CO2.

ASLo 2013, Oral presentation

Session #:SS16
Date: 2/21/2013