THE DISTRIBUTION OF NUTRIENTS IN THE LABRADOR 

 SEA, SUMMER 1963^ 



David A. McGill and Nathaniel Corwin 



Woods Hole Oceanographic Institution 



Woods Hole, Mass. 



For the second year, determinations of nutrient concentrations 

 have been made from samples obtained dm'ing the annual postseason 

 cruise of the International Ice Patrol between Labrador and Greenland. 

 The results greatly augment the information available on the chemical 

 characteristics of the area, since some comparisons with previous 

 data are possible. Some evidence of annual differences in the amount 

 of deep w^ater formation is discussed. 



METHODS 



Sea water samples were collected on stations of the USCGC 

 Evergreen and stored in deep-freeze lockers for the duration of the 

 cruise. The analyses were conducted by the authors at the Woods 

 Hole Oceanographic Institution with the assistance of Mr. John 

 Schilhng and Mrs. Juanita Mogardo. Determinations of the total 

 phosphorus, nitrate- and nitrite-nitrogen and the silicate-silicon 

 followed techniques described in a previous report (Corwin and 

 McGill, 1963). The inorganic phosphate determinations were made 

 by the use of an acidic molybdate solution containing ascorbic acid 

 to reduce the phospho-molybdic complex in the presence of antimony 

 tartrate for more rapid color development (Murphy and Riley, 1962). 

 This method replaces the stannous chloride reduction used previously. 

 The ascorbic acid method is considered to be more reliable, since the 

 molybdenum blue color formed is stable for long periods. Comparison 

 of the various existing techniques of phosphorus determination, 

 made by Jones and Spencer (1963) and others, suggests that the 

 ascorbic acid method is especially dependable at very low concen- 

 trations. 



Distribution profiles for the data on the section from South Wolf 

 Island, Labrador, to Cape Farewell, Greenland, are presented for 

 the significant nutrient quantities. In these figures the area of 

 maximum concentration for each parameter is shaded. 



1 This work has been supported in part by the Office of Naval Research under contract Nonr-2196(00)NR. 

 083-004. Contribution No. 1457 from the Woods Hole Oceanographic Institution. 



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