Dr. Prosper Zigah is a postdoctoral scholar at Woods Hole Oceanographic Institution. Dr. Zigah studies the organic carbon that is dissolved in seawater known as dissolved organic carbon (a.k.a DOC). DOC constitutes about a third of all actively recycling carbon in the biosphere with a carbon inventory similar to that of the atmosphere. Changes in the DOC pool could have important implications for the global climate. But there are major gaps in our knowledge of the sources of DOC and how DOC cycles in the ocean. We can understand more about the cycling of DOC in the ocean by using the radiocarbon dating method to obtain the ‘age’ of the DOC. The radiocarbon dating of marine DOC in the past has mostly been made on the total DOC. However, because the DOC pool is a complex mixture of compounds from different sources, Dr. Zigah think we can learn more about the DOC cycle by focusing on the major groups of compounds that make up the DOC. On this research cruise aboard R/V Thompson, Dr. Zigah is using different filtration techniques to isolate different sizes and polarity fractions of DOC along nearshore-offshore transect in the North Pacific, just West of San Diego. By performing radiocarbon assays on these DOC fractions, Dr. Zigah believe we will have a better understanding of the sources and cycling of DOC in the ocean.