TABLE 1 



Cruises on which sediment samples were collected. 



AK-47 



Akademik Korolev 



26 July-24 August 1988 



110 



Chukchi Sea 



« - Akademik Korolev Cruise 

 o - ISHTAR Cruises 







oo 



CD 



CD 



59 



Fig. 1 . Location of stations from which sediment samples were recovered. 



5"N, is used for "N/"'N data where atmospheric nitrogen is 

 taken as the standard. Based on repeated analysis of samples 

 and standards, the 5" C values have an error of less than 

 0. 1 per mil C'/,,,, ) and 5''^ N of less than 0.3 per mil. Sealed tube 

 oxidations were used to prepare CO, suitable for isotopic 

 analysis (adapted from Sofer, 1980). A sealed tube reduction 



of organic nitrogen (adapted from Macko, 1 98 1 ) in Pyrex tubes 

 at 590°C combined with a postreduction purification, provided 

 Nt suitable for nitrogen isotope analysis. 



Carbon and nitrogen elemental compositions of the dried 

 sediments were measured using a Perkin-ElnierCHN- Analyzer, 

 model 240 B. Sufficient numbers of blanks, standards, and 

 replicated samples were determined to allow an estimated 

 standard deviation of ±2% of the amount present. 



Perhaps one of the more readily assimilated means of 

 representing large amounts of data is by contour plotting on a 

 map of the study area. While an attempt has been made to be 

 completely objective in the selection of contour lines, some 

 subjectivity is probably inherent in the "canned" computer 

 program used in these presentations ("SURFER Ver. 4, 1989," 

 Golden Software, Inc.). 



Results and Discussion 



Because only the clay-silt fraction size was used for 

 analysis, the C and N quantitative data do not represent values 

 for the total sediment and thus cannot be used as direct 

 indicators of total sediment organic carbon or nitrogen. This 

 organic fraction probably represents, for the most part, material 

 added to the sediments either directly or through incorporation 

 into fecal pellets and other small particles. It includes material 

 reworked or produced by bacterial or other nano-organisms. 

 By restricting the analysate to the fine-grained fraction, it was 

 hoped that the carbon and nitrogen analyzed would represent 

 an integrated value uninfluenced by inclusion of even a small 

 quantity of macro-organisms. 



Results of isotopic and elemental analyses of the sediments 

 are summarized in Table 2 and are incorporated into graphical 

 representations in the isopleths for 5" C, 5'^ N. weight percent 

 C, weight percent N, and C/N ratios of Figs. 2 through 6. 

 Although not all of the samples collected have been analyzed 

 and results for some stations are incomplete, all of the contour 



334 



