Estimation of Western Arctic Ocean organic carbon sources using Bayesian analysis of bulk δ13C and δ15N
Abstract
The organic carbon cycle of the Western Arctic Ocean is one of the most significant remaining obstacles to establishing a pan-Arctic organic carbon cycle. With modifications to sea ice extent, timing and abundances of the seasonal productivity and alteration in fresh water discharge expected from global climate change, a better estimate of the sources of organic carbon to the ocean sediments has become more pressing. However, the presence of three end-members: terrestrial organic carbon supplied by coastal erosion and riverine discharge, pelagic marine production from plankton and significant sea ice algal productivity complicates the traditional use of bulk isotope data to construct linear mixing models. Instead, in this report, we use a Bayesian analysis of the bulk data, allowing for the construction of robust mixing models and enabling the probabilistic estimation of the relative contributions of the three sources. Bulk isotope data from Shelf Basin Interaction cores, together with biomarker and compound specific isotope data from the same cores are used to quantify the various contributions and construct a model of the carbon cycle in the Western Arctic Ocean. Bulk carbon is enriched (δ13C has a mean value of -19.4±1.3%), but the concentration of terrestrial biomarkers is also high. Based upon Bayesian analysis, 50-70% of the organic carbon is of marine origin. Terrestrial carbon made up 15%, with sea ice algal carbon accounting for the remaining 25-35%. We suggest that the discrepancy between the enriched bulk carbon and high terrestrial biomarker concentration is better explained by preferential preservation of the more recalcitrant terrestrial biomarkers than by a very high terrestrial contribution to bulk carbon.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.B21E0313M
- Keywords:
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- 0454 BIOGEOSCIENCES / Isotopic composition and chemistry;
- 1635 GLOBAL CHANGE / Oceans;
- 4806 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Carbon cycling;
- 4870 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Stable isotopes