Basin water (Kinney, Arhelger, and Burrell, 

 1970) in the same depth range (35-50 m). 



Water near the bottom in the East Siberian 

 Sea was found by Codispoti and Richards 

 (1963) to contain concentrations of phosphate 

 and silicate which are quite similar to those 

 found near the bottom in the northern edge of 

 the WEBSEC-70 area. However, the tempera- 

 ture, salinity, and concentration of nitrate were 

 unlike those found in the WEBSEC-70 area. 

 These dissimilarities and the lack of evidence 

 of flow from the East Siberian Sea to the east- 

 ern Chukchi Sea rule out the East Siberian Sea 

 as a source of the WEBSEC-70 near-bottom 

 water. 



Horizontal distributions of dissolved nu- 

 trients on the sea surface and 10-m surface 

 (figs. 19, 20, 22, 23, 25, 26, 28, 29) showed a 

 general northwestward decrease in concentra- 

 tions of all those measured. Such a decrease 

 would be expected if the flow were northwest- 

 ward and photosynthesis were taking place at 

 these levels. However, Fleming and Heggarty 

 (1966) estimated the residence time for water 

 in the southeastern Chukchi Sea to be only 

 about 10 days, scarcely enough time to develop 

 the gradients observed under fall light condi- 

 tions. The residence time may be substantially 

 longer than the estimate, perhaps because of 

 the formation of eddies northeast of Cape 

 Lisburne and the reduction of flow through the 

 area by strong northeasterly winds. 



An interesting feature visible on nearly all 

 charts of horizontal distributions of water 

 properties was an area of vertically well mixed 

 cold water with relatively high nutrient con- 

 tent, found extending westward from Point 

 Lay. Steep horizontal gradients were found in 

 the concentrations of phosphate and nitrate at 

 all levels. The high nutrient load of this water 

 probably was the result of incorporation of 

 nutrients from the bottom sediments into the 

 overlying water and vertical mixing caused by 

 convective overturn and wind mixing, since the 

 stations involved were occupied late in the 

 cruise during a period of strong cooling and 

 rapid freezing. 



The distribution of oxygen in the area of 

 study showed little variation, particularly in 

 terms of percent saturation (figs. 16-18). The 

 slightly lower oxygen values observed near 

 bottom along the northern boundary of the 



area of study are characteristic of water from 

 near bottom in the central Bering Strait. Con- 

 vective processes produced concentrations very 

 near saturation in the rest of the water column 

 along the northern boundary and in the rest of 

 the area of study. 



Currents — Direct Measurement 



Current meter records obtained during 

 WEBSEC-70, which have been digitized and 

 summarized (figs. 46-74), revealed a wide 

 variation in magnitude and direction. Tidal 

 variations were not evident in the 30-hour rec- 

 ords (15-minute average progressive vector 

 plots, figs. 60 and 74) from station 8. This is 

 not surprising because the currents associated 

 with the mixed semidiurnal tides in the ea.stern 

 Chukchi Sea are relatively weak. Fleming and 

 Heggarty (1966) reported measurements of 

 tidal currents of less than 0.1 kt just south of 

 Point Hope. 



During the 31 hours of current measurement 

 at station 8, the motion of the vessel swinging 

 at anchor introduced variation into the velocity 

 records. A log of the vessel's heading, recorded 

 at 15-minute intervals for 13 hours, showed 

 that the vessel moved through an arc of 150° 

 (210-360° T) during the full period, and 

 through an average arc of 15.2° in 15 minutes. 

 Assuming uniform motion during the 15- 

 minute period, a swing of 15.2° would produce 

 a recorded velocity of 0.09 kt at right angles 

 to the vessel's heading. The maximum swing 

 observed during any 15-minute period was 50°, 

 which similarly would yield a recorded velocity 

 of 0.29 kt. The vector average near-bottom 

 current speed during the 31-hour period was 

 only 0.08 kt, which is only slightly larger than 

 the average velocity imparted by the ship's 

 swinging at anchor. The spurious velocity rec- 

 ord due to the vessel's motion thus renders 

 short-term averages or instantaneous velocities 

 in the record nearly useless. The strip chart 

 from the 10-m current meter shows variation 

 in direction (assumedly due to swinging at 

 anchor) with no obvious general period. Only 

 the trends revealed by progressive diagrams or 

 long term vector averages can be considered as 

 significant under these circumstances. 



Currents at the 10-meter depth (fig. 75) 

 generally fell within the same quadrant and 

 often the same octant as the wind velocity (fig. 



9 



