Molecular and Isotopic Coupling between Pelagic and Benthic Carbon Cycling-a Proof of Concept

Skidaway Institute Of Oceanography, Savannah GA

Investigators

Abstract

ABSTRACT OCE-9911678 The quantitative relationship between organic matter falling through the water column and that accumulating in seafloor sediments presents one of the major challenges to understanding the organic chemistry of the ocean. Although organic matter produced biologically in the upper ocean transfers a marine chemical signature to the sediments, the organic matter in surface sediments looks very different: it is compositionally different, apparently enriched with terrestrial biomarkers and having radiocarbon ages suggesting input of old reworked material. In this study, scientists at the Skidaway Institute of Oceanography will use paired samples of organic matter collected in sediment traps and underlying sediments to deduce the chemical character of the organic matter that is degraded (and thus removed) from sinking organic matter before it accumulates on the seafloor. First, they will determine the molecular and isotopic character of key biomarkers in sediment trap/sediment pairs from a variety of oceanic environments. Secondly, they will use molecular and isotopic distributions to constrain the character of the bulk of organic carbon that is degraded in the water column and at the sediment-water interface, the loss of which determines the nature of the organic carbon that can be accumulated in sediments and preserved in the sedimentary record.