Nitrate-nitrogen was determined following reduction with hydrazine 

 in the presence of copper according to the method of Mullin and Riley 

 (1955a). Samples were read on a DU spectrophotometer at 524 m/x. 

 The value obtained is the total of both the nitrate and the nitrite 

 present in a sample. 



Nitrite-nitrogen was measured colorimetrically following diazotiza- 

 tion with sulfanilic acid coupling with alphanaphthylamine according 

 to the method of Rider and Mellon (1946). The sample was read on a 

 DU spectrophotometer at 520 m/x. 



Silicate-silicon was also measured colorimetrically, using the method 

 described by Mullin and Riley (1955b) which depends upon the 

 development of a molybdenum blue complex in acid solution after 

 oxidation with metolsulfite-oxalate solution. Samples were read at 

 882 mix on a DU spectrophotometer. 



Simplified profiles of the data for three sections in the Labrador 

 Sea and Baffin Bay are drawn in which the distribution is indicated by 

 smooth contours omitting c^uestionable points. The area of maximum 

 concentration for each figure is shaded. 



DISTRIBUTION OF NUTRIENT PARAMETERS 



The inorganic phosphate distribution in the section from South 

 Wolf Island, Labrador to Cape Farewell, Greenland shows a con- 

 siderable homogeneity in the deep water (fig. 49). Values of 1.20 

 MgA/l occur from 200 meters to the bottom in the western half of the 

 section and throughout about half this depth range in the eastern 

 part of the region. A phosphate maximum of concentrations greater 

 than 1.30 MgA/1 is found in the western region between 1,000 and 2,500 

 meters. Values near the surface are low but show a quick rise to 

 values of 1.00 MgA/1 or greater near 100 meters. Variations in the 

 depth of the 1.00 MgA/1 concentration may be a reflection of the 

 strong surface currents which are present near each coast. 



Figure 50 presents the inorganic phosphate distribution in a longi- 

 tudinal section that runs northward into Baffin Bay. The high inor- 

 ganic phosphate level appears to originate from the north and thence 

 to spread southward. The section in the midline of the basin does 

 not appear to follow the core of the high phosphate water, which is 

 somewhat more pronounced on the western side of the basin. Such, 

 at least, is the impression given by figure 51, in which the inorganic 

 phosphate in a section from Loks Land to the coast of Greenland is 

 shown. The high inorganic phosphate concentration is found in the 

 depth of Baffin Bay well inside and below the region of the sill in 

 Davis Strait (fig. 50). It appears that water with an inorganic phos- 

 phate content of about 1.30 MgA/1 escapes over the sill and thus 

 contributes to the maximum value observed in the southward sections. 

 The concentrations of phosphate in Baffin Bay below sill depth in- 

 crease regularly to values of more than 2.00 jugA/l at the bottom. 



80 



