TABLE 2 



Attribute 



Summary of Analyses of Sediment Samples 

 5" C 5" 



N 



C/N 



Average 

 Std. Dev. (± 1 ) 

 No. of Samples 

 Maximum Value 

 Minimum Value 



figures show a common trait for the measured parameters; viz., 

 organic matter generated or deposited in the sediments of the 

 eastern part of the study area is readily distinguished from that 

 of the western part. 



Carbon 



In Fig. 2, six general locations show enrichment in organic 

 carbon: southern Bering Sea, central and northern Gulf of 

 Anadyr, western Anadyr Strait, just north of the Bering Strait, 

 and western Chukchi Sea. Though other parts of the study area 

 are less organic-rich than these "hot spots," the entire Bering- 

 Chukchi locale is abundant in carbon comparable to many 

 other shelf environments. The average (0.88, Table 2), for 

 instance, is not unlike that found for the Gulf of Mexico and 

 other shelf environments of the world (Plucker, 1970; Newman 

 etal., 1973; Gearing ef«/., 1977). 



The distribution of the carbon isotope values (Fig. 3) 

 shows lighter (more negative) values east and north of 

 St. Lawrence Island as compared with those of the southern 

 Bering Sea, Gulf of Anadyr, or the western Chukchi Sea 

 Presumably there is a considerable contribution of terrestrial 

 organic carbon from the Kvichak, Kuskokwim, and Yukon 

 Rivers and other minor drainage systems of Alaska. No such 

 sources are apparent in the western part of the study area due 

 to drainage from the Chukchi Peninsula. 



The del 1 3-C values grade "lighter" away from the Yukon 

 River toward the Seward Peninsula, suggesting either greater 

 deposition of the terrestrially derived organic matter at some 

 distance from the river delta (Dean, 1986, personal 

 communication ) or a contribution from the Seward Peninsula, 

 perhaps from older mining operations on shore or more recent 

 pollution from anthropogenic sources at Nome, Alaska. Values 

 of the Gulf of Anadyr and the western Chukchi Sea resemble 

 those of the open ocean. They show no contribution of 

 terrestrial organic matter from the Chukchi Peninsula or from 

 the Anadyr River. 



Nitrogen 



Del 1 5-N values of the sediment fines are shown graphically 

 in Fig. 4. Values of 8 to 9 per mil are common throughout the 

 study area. They become somewhat lighter in the Gulf of 

 Anadyr (7 per mil) in the southern Bering Sea (4.5 per mil) and 

 in the eastern Chukchi Sea (4.5 per mil). Three isotopic "lows" 



Chukchi Sea 



Fig. 2. Areal dislribulion of carbon concenlrations in sediments. 



occur at the biological "hot spots" north of St. Lawrence Island 

 and two locations just north of the Bering Strait in the central 

 Chukchi Sea. An isotopic "high" is associated with the output 

 of the Yukon River. 



Organic nitrogen content of sediment fines, shown in 

 Fig. 5, is fairly consistent with the organic carbon content. 

 Figure 6 shows the relationship between the two components. 

 The relatively high cortelation is not unusual and merely 

 reflects the similarities of all biological tissues. The scatter 

 about the regression line illustrates the relative variations of the 

 C/N ratios. The slope of the regression line in Fig. 6 corresponds 



335 



