Radiocarbon Studies of Dissolved and Particulate Organic Carbon Cycling in the North Pacific and Antarctic Oceans

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9501531 BAUER Organic carbon pools will be studied at two open ocean sites that reflect potential differences in carbon cycling and transformations in polar and temperate regions. Carbon isotopic signatures ( 14C, 13C) and concentrations of dissolved, colloidal and particulate organic carbon (DOC,COC,POC) will be measured at Station M in the Northeast Pacific Ocean and in the Antarctic Ocean south of the Indian Ocean. The following carbon pools will be studied: ultra-violet and high-temperature catalytically-oxidizable fractions of DOC (DOCuv and DOChtc), suspended and sinking POC (POCsusp and POCsink), COC specific organic constituents (total hydrolyzable amino acids THAA , total carbohydrates TCHO , total lipids) of suspended and sinking POC and of COC, detrital aggregates on the seafloor, marine snow, and dissolved inorganic carbon (DIC). The following questions will be addressed: 1) Do the 14C profiles in Antarctic DOC, POCsusp, and COC support the hypothesis that deep DOC is transported quasi-conservatively through the world's deep ocean? 2) How does the lateral transport of shelf/slope derived organic matter to the deep sea change with time and what is the extent of adsorption of DOC onto POCsusp and POCsink in the water column? 3) From what depths do specific organic constituents of the COC,POCsink, and POCsusp, originate and how are they recycled? 4) What are the sources of carbon to detrital aggregates and marine snow, and are the labile, surface-derived compounds utilized exclusively during remineralization? 5) What is the overall labile and refractory nature of DOC with respect to its heterotrophic utilization, and what does the 14C signature of microheterotrophic biomass reveal about the assimilation of DOC/COC/POC in the deep ocean?