Novel analytical strategies for tracing the organic carbon cycle in marine and riverine particles
Citable URI
https://hdl.handle.net/1912/8658Location
Antarctic OceanAmazon River
DOI
10.1575/1912/8658Keyword
Carbon; Carbon dioxide; AtmosphereAbstract
Particulate organic carbon (POC) in the ocean and mobilized by rivers on land
transfers ~0.1% of global primary productivity to the deep ocean sediments. This small
fraction regulates the long-term carbon cycle by removing carbon dioxide from the
atmosphere for centuries to millennia. This thesis investigates mechanisms of POC
transfer to the deep ocean by analyzing particles collected in transit through two globally
significant carbon reservoirs: the Southern Ocean and the Amazon River Basin. These
endeavors test the hypothesis that organic matter composition controls the recycling and
transfer efficiency of POC to the deep ocean, and illustrate new applications for ramped
pyrolysis/oxidation (RPO), a growing method of POC characterization by thermal
stability. By coupling RPO to stable and radiocarbon isotope analyses of riverine POC, I
quantify three thermally distinct soil organic carbon pools mobilized by the Amazon
River, and evaluate the degradability and fate of these different pools during transport to
the coastal Atlantic Ocean. More directly, RPO analyses of marine samples suggest that
POC transfer in the water column is in fact selective. Observations of consistent
biomolecular changes that accompany transport of phytoplankton-derived organic matter
to depth across the Southern Ocean support the argument for preferential degradation of
specific POC pools in the water column. Combining discussions of POC recycling and
transfer across both marine and terrestrial systems offer new perspectives of thermal
stability as a proxy for diagenetic stability and POC degradation state. The challenges of
interpreting RPO data in these two environments set the stage for applying the technique
to more controlled experiments that trace POC from source to long-term sink.
Description
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy
at the
Massachusetts Institute of Technology
and the
Woods Hole Oceanographic Institution
February 2017
Collections
Suggested Citation
Thesis: Rosengard, Sarah Z., "Novel analytical strategies for tracing the organic carbon cycle in marine and riverine particles", 2017-02, DOI:10.1575/1912/8658, https://hdl.handle.net/1912/8658Related items
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