MARINE ORGANIC CARBON AND RADIOCARBON-PRESENT AND FUTURE CHALLENGES

We discuss present and developing techniques for studying radiocarbon in marine organic carbon (C). Bulk DOC (dissolved organic C) Delta C-14 measurements reveal information about the cycling time and sources of DOC in the ocean, yet they are time consuming and need to be streamlined. To further elucidate the cycling of DOC, various fractions have been separated from bulk DOC, through solid phase extraction of DOC, and ultrafiltration of high and low molecular weight DOC. Research using C-14 of DOC and particulate organic C separated into organic fractions revealed that the acid insoluble fraction is similar in C-14 signature to that of the lipid fraction. Plans for utilizing this methodology are described. Studies using compound specific radiocarbon analyses to study the origin of biomarkers in the marine environment are reviewed and plans for the future are outlined. Development of ramped pyrolysis oxidation methods are discussed and scientific questions addressed. A modified elemental analysis (EA) combustion reactor is described that allows high particulate organic C sample throughput by direct coupling with the MIniCArbonDAtingSystem.

Automated summary

The present article discusses techniques for studying radiocarbon in marine organic carbon, including measurements of dissolved organic carbon (DOC) Delta C-14 and separation of various fractions for radiocarbon testing. Compound specific radiocarbon analysis for studying biomarkers in the marine environment as well as ramped pyrolysis oxidation methods are also reviewed. A modified elemental analysis combustion reactor is described for high sample throughput.