oceanographic program. Its primary objective 

 was the recovery of the four instrumented 

 buoys placed near 74° S. and 40° W., which was 

 not achieved due to severe ice conditions. Sev- 

 eral other programs were carried out during 

 the expedition : seal census ( University of Min- 

 nesota), bottom coring (University of Califor- 

 nia, Los Angeles), and benthic zonation (Uni- 

 versity of Connecticut). The Coast Guard 

 Oceanographic Unit obtained hydrographic da- 

 ta, bottom photographs, and nutrient samples. 

 More detailed information on the programs can 

 be found in the paper of Hufford and Sea- 

 brooke (in press). 



DATA ACQUISITION 



The USCGC GLACIER operated in the Wed- 

 dell Sea from February 1 to March 15, 1968 

 and again from February 17 to March '24, 1969. 

 The station locations are shown in Figure 1. 

 Water was sampled as close to the sea floor 

 as possible with a Benthos pinger attached to 

 the end of the hydro-wire. The water samples 

 were obtained in Teflon-coated Nansen bottles 

 and in some cases, from plastic (PVC) Niskin 

 bottles. Acquisition of the physical data ob- 

 tained is described by Hufford and Elder 

 (1969). 



Water samples were analvzed at sea for sal- 

 inity, dissolved oxygen, pH, inorganic phos- 

 phate, nitrate-Nitrogen, nitrite-Nitrogen, and 

 silicate. Techniques described in the manual of 

 Strickland and Parsons (1965) were used to 

 determine pH, silicate, nitrate, nitrite, phos- 

 phate and dissolved oxygen. Salinity was de- 

 termined using an inductive salinometer. 

 Frozen samples for ammonia and total phos- 

 phorus were returned to the U.S. Coast Guard 

 Oceanographic Unit for later analysis. Nitro- 

 gen data for stations 30-60 and phosphorus 

 values for stations 43-60 from the 1968 cruise 

 proved unreliable due to accidental thawing 

 after malfunction of the spectrophotometer re- 

 quired that the samples be frozen. However, 

 a few individual nitrate values from stations 

 30-60 which were quality controlled have been 

 used in cross sections A and B. 



Section profiles of the data taken in the 

 Weddell Sea during the '68 and '69 cruises are 

 given in Figures 2-17. The distribution of the 

 chemical parameters measured is indicated by 



smooth contours, omitting any questionable 

 points. Exact placement of the individual sec- 

 tions may be obtained from the map of station 

 positions and section locations in Figure 1. 



DISTRIBUTION OF NUTRIENTS 



The ranges of concentration for the various 

 nutrients in the Weddell Sea were : 



inorganic phosphate 1.1-2.7 /xg-at/L 



nitrate-Nitrogen 16-32 /ig-at/L 



nitrite-Nitrogen 0.1-0.5 yxg-at/L 



silicate-Silicon 39-125 /..g-at/L 



ammonia (amino acids) 0.1-6 jug-at/L 



The surface waters of the southwest and 

 southeast regions of the Weddell Sea have com- 

 parable nutrient concentrations. However, the 

 central region was an area of lower concentra- 

 tions. These lower values may be due to the 

 heavy perennial ice cover, but many factors 

 affecting this area are unknown and further 

 investigation is needed. 



In general, the vertical distributions of the 

 nutrients in the Weddell Sea fit the classical 

 description. On the continental shelf, phosphate, 

 nitrate, and silicate concentrations increase 

 with depth to about 50 meters, then remain 

 constant to the bottom. Off the shelf, phosphate, 

 nitrate and silicate generally increase with 

 depth until a maximum is reached at an in- 

 termediate depth (400-1600 meters). This 

 maximum is associated with the Warm Deep 

 Layer. Farther north, in the deep basin, phos- 

 phate and nitrate distribution is similar to 

 the area just off the shelf, but the silicate 

 concentration increases monotonically with 

 depth to within a few hundred meters of the 

 bottom, reaching values as high as 120 ;ug-at/L. 



Nitrite and ammonia are intermediate prod- 

 ucts of organic decomposition. Both fractions 

 tend to accumulate below the euphotic zone 

 where regeneration to nitrate is assumed to be 

 intense (Redfield, Ketchum and Richards, 

 1963). In the Weddell Sea, nitrite and am- 

 monia were present in highest concentrations 

 in the upper 200 meters. However, both were 

 present in deeper waters. This may be due to 

 a large mortality of sinking phytoplankton 

 which are decomposing at depth. 



