The goals of our research are twofold. First, we seek to understand why the 14C age of marine dissolved organic carbon (DOC) is thousands of years old, despite evidence that most of it is produced in the surface ocean during photosynthesis.  Black carbon, produced on land by incomplete combustion of fossil fuels and biosphere burning, is a small but important component of old oceanic DOC. We are measuring concentrations and 14C in marine DOC, solid phase extracted DOC (SPE-DOC), black carbon and other compounds throughout the major oceans to discern the main controls on DOC cycling. Second, how has ocean circulation changed in the tropical and subtropical Pacific during the past millennium?

We use accelerator mass spectrometry (AMS) and preparative capillary gas chromatography (PCGC) in our lab that is part of the Keck Carbon Cycle AMS Lab to measure radiocarbon in samples as small as 2 µg C. We are also using spectroscopic and other spectrometric techniques designed to characterize portions of the DOC.