was found in the vicinity of the edge of the 

 polar ice pack during the early portion of 

 WEBSEC-70 (figs. 7, 8, 10, 11, 37, 38). The 

 layer, which was easily distinguished from 

 water beneath and adjacent to it, was quite 

 limited in its vertical and horizontal extent 

 (about 10 m or less thick and a few miles from 

 the pack edge), thus representing a small 

 volume relative to the total volume studied dur- 

 ing the cruise. 



Freezing of sea ice will produce a change in 

 the entire water column, making it colder 

 (down to about —1.8° C) and more saline 

 (>31 ppt here). These changes occur step- 

 wise, in temperature first, then in salinity when 

 the freezing point is reached. Many of the 

 stations occupied during the last portion of the 

 cruise (stations 72-87) showed the effects of 

 rapid cooling and freezing (figs. 7, 8, 9). 

 Temperature-salinity plots of these stations 

 (fig. 35) are virtually points, indicating the 

 nearly isothermal and isohaline conditions in 

 the water column produced by convective over- 

 turn resulting from the strong cooling and 

 freezing of sea ice. 



Inclusion of water from near bottom in the 

 central Bering Strait would decrea.se the tem- 

 perature and increase the salinity of the water 

 column (fig. 36) . The effects of this water 

 category were found near bottom on stations 

 in the northwestern corner and along the 

 northern boundary of the WEBSEC-70 area of 

 investigation. Stations in deeper portions of the 

 Chukchi Sea farther north (inaccessible during 

 WEBSEC-70) probably would reveal this 

 water category to be a common component of 

 the water column. 



Water properties along the western edge of 

 the area of investigation (stations 44-60, sec- 

 tion B-B'), which would be "upstream" in a 

 current pattern such as that described by previ- 

 ous investigators, varied significantly in their 

 horizontal and vertical distributions (figs. 

 39-45). Maximum temperatures (>3" C) at all 

 depths were found in the center of the section 

 (stations 49 and 50), where the water column 

 was nearly isothermal. Minimum temperatures 

 (<1° C) in the section were found near the 

 surface on station 44 (near the ice pack) and 

 near the bottom on .station 48. 



The distribution of salinity along the section 

 (fig. 40) generally did not parallel the distribu- 



tion of temperature. Salinity changed very 

 little northward from Cape Lisbume (station 

 60) until beyond the midpoint (station 49), 

 and the water column was nearly isohaline in 

 the section between stations 49 and 60. North 

 of station 49 salinity increased at all levels, but 

 most rapidly near bottom, where a maximum 

 of 32.66 ppt was found on station 48. 



The combination of temperature and salinity 

 values observed near bottom on the stations at 

 the northern end of the section (stations 44, 48, 

 and 49) and along the northern boundary of 

 the study area closely correspond with those 

 observed below 20 m in the central Bering 

 Strait (fig. 33) during a cruise of the USCGC 

 NORTHWIND in October 1962 (U.S. Coast 

 Guard, 1964). In addition, the distributions of 

 dissolved nutrients in the near bottom water on 

 this section (figs. 42-45) showed higher values 

 for each nutrient sampled. The higher nutrient 

 concentrations add to the hypothesis that the 

 near bottom water on stations 44, 48, and 49 

 came from the central Bering Strait. All these 

 water properties correspond well with the 

 characteristics of a Bering Strait water mass 

 described by Kinney, Burrell, et al. (1970), 

 which was found at the surface in the western 

 strait and at the bottom in the center of the 

 strait, and was characterized by high nutrients, 

 low organics, high salinity, and low tempera- 

 ture. This mass also was thought by Kinney, 

 Burrell, et al. to make up the bottom water of 

 the central and western Chukchi Sea. 



The possibility that the near-bottom water 

 found along the northern edge of the 

 WEBSEC-70 area may have come from the 

 Arctic Basin instead of the central Bering 

 Strait is negated by the following observations : 

 (1) The WEBSEC-70 near-bottom water was 

 warmer by 2-4° C than Arctic Basin water 

 (Coachman and Barnes, 1961) of the same 

 salinity range (31.8-32.6%o) and density range 

 (cT, 25.5-26.5). (2) The WEBSEC-70 near- 

 bottom water contained less dissolved oxygen 

 (about 1.5-2.0 ml/1 less) and more silicate 

 (about 20-30 ng-at/1 more) than Arctic Basin 

 water (Kinney, Arhelger, and Burrell, 1970) 

 of the same density range. (3) The WEBSEC- 

 70 near-bottom water contained substantially 

 less oxygen, more silicate, more phosphate, 

 more nitrate, and was warmer than Arctic 



8 



