Date of Award

1-1-2022

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Specialization

Marine Geology and Geophysics

Department

Oceanography

First Advisor

Rainer Lohmann

Abstract

Sedimentary black carbon (BC) accumulation in shelf sediment along the US East Coast reflected incomplete combustion from natural and human activities. One of the BC materials is soot, a light-absorbing particulate matter, deposited and incorporated with the sediment consisting of various materials, including inorganic and organic carbon. We collected sediment core from two stations in North Carolina (ST02) and Florida (ST12) in the spring of 2017. We analyzed soot BC using the chemo-thermal oxidation method at 375 C (CTO- 375), total organic carbon (TOC) from inorganic carbon removal, stable carbon isotope δ13C from each BC and TOC sample, Polycyclic aromatic hydrocarbon (PAH), and sedimentation rates based on lead-210 data. BC/TOC ratios in ST02 and ST12 ranged from 9-28% and 8-10%, while average sedimentation rates were 0.15 and 0.33 cm/year, respectively. Stable carbon isotope δ13C revealed the marine origin of the organic carbon, and a more depleted soot BC fraction closer to that of C3-plants. Based on these findings, BC accretion was similar at both sites, whereas TOC and sedimentation rates were higher at ST12. PAH diagnostic ratios indicated shifting from biomass to petroleum combustion for ST02 and biomass combustion for ST12. Further research is needed to gain clarity about BC using the radioisotope Δ14C ratio in order to distinguish fossil fuel from non-fossil fuel sources.

Available for download on Wednesday, May 17, 2023

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