13C/12C composition of marine dissolved organic carbon

The stable isotopic composition of marine dissolved organic carbon (DOC) was measured with a high temperature, sealed tube combustion technique. The delta(13)C values of DOC ((DOC)-C-13) were approximately -22 parts per thousand for all samples that were collected (1) in a monthly survey conducted in Woods Hole Harbor, (2) in a spatial survey across Georges Bank during a spring bloom period, and (3) in depth profiles near Bermuda, Georges Bank and in the eastern Equatorial Pacific. The (DOC)-C-13 values were uniform in waters of varying DOC content, including low DOC deep waters and high DOC surface waters, indicating little overall isotopic fractionation during formation and degradation of marine DOG. The -22 parts per thousand (DOC)-C-13 values are similar to those observed for average marine particulate and sedimentary organic material, and exclude a large contribution from -27 parts per thousand terrestrial DOC to ocean pools. (C) 1998 Elsevier Science B.V. All rights reserved.