deepest to 1000 m depth at the seaward-most station on each transect We anticipate that our 

 temporal coverage of this region will be on a seasonal basis during the upcoming field year(s). 



METHODS AND PLATFORMS 



Our methods focus on the measurement of total organic and inorganic carbon pools and 

 the carbon isotopic composition ( 14 C and 13 C) of each pool. Carbon contents of each of the 

 pools are determined by high-temperature combustion (DOC, COC and POC), ultra-violet 

 oxidation (DOC, COC) or stripping after acidification (total dissolved inorganic carbon, DIC), 

 followed by purification and quantification on vacuum extraction lines. Isotopic measurements 

 of carbon in each of the pools are made by stable isotope ratio mass spectrometry ( 13 C) and 

 accelerator mass spectrometry ( 14 C). Thorium isotope measurements of selected samples are also 

 being made on in situ pump samples taken in conjunction with K. Buessler. Appropriate 

 sampling platforms include vessels with standard hydrowire capabilities and the ability to 

 accommodate a clean van for natural radiocarbon work. 



STRENGTHS AND LIMITATIONS OF PROPOSED RESEARCH 



The strength of this approach of measuring carbon distributions and fluxes is that 

 information is obtained on both the sources and residence times of carbon in each of the organic 

 and inorganic carbon pools. Coupled with hydrographic and water mass circulation data, this 

 information is critical for determining the net fluxes of each of the bulk carbon pools along and 

 across the shelf and away from their indicated source areas. Thus, average rates and residence 

 times of the carbon pools are obtained. This information then serves as a benchmark from which 

 to interpret the distributions and fluxes of all other components of the DOC, COC and POC 

 pools. 



STATUS OF RESEARCH 



Prior to our first cruise to the Atlantic continental margin, work on the distribution and 

 fluxes of organic carbon and isotopes in DOC, COC and POC pools of the eastern North Pacific 

 identified sampling and analytical challenges that were resolved prior to sampling on the Atlantic 

 shelf. Data from our North Pacific site serves as a starting point from which we may be able 

 to anticipate the various relationships between each of these three pools on the Atlantic shelf. 

 Samples were collected during a 2-week cruise to the Atlantic shelf in April 1994 and are 

 currently being processed for isotopic characterization. 



Keywords: DOC/POC/COC fluxes, sources, natural isotopes, residence times 



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