were plotted as a function of some property more uniformly common 

 to all water masses. Considering the possiblity of changes in depth 

 as the water moved from one geographical location to another, 

 potential density ^ was chosen as the property against which to plot 

 the phosphorus concentration. The individual station curves did 

 seem to have shapes characteristic of the water masses. Average 

 curves for each of the water masses were then drawn and the probable 

 departure of individual observations from the average curve computed. 

 The average curves are shown in figure 40 as solid lines bracketed 

 by broken lines indicating the probable departure. Thus the Labrador 

 Current water had a practically constant concentration of total 

 phosphorus of about 1.0 to 1.1 microgram-atoms per liter down to 

 intermediate depths below which there was an increase to about 

 1.25 microgram-atoms per liter in the deep water. The Atlantic 

 Current water had much lower values near the surface, increased to 

 an intermediate maximum of more than 1.5 Mga/L, and then decreased 

 approaching in deep water the values in the Labrador Current water. 

 The mixed water showed a relationship roughly intermediate between 

 the Atlantic Current water and the Labrador Current water, and, 

 like the T-S characteristic, closer to the curve of Labrador Current 

 water than the curve of Atlantic Current water. 



Thus the concentration of total phosphorus was shown to be a 

 water mass tracer in the Grand Banks region, but not a very good 

 tracer. The data for the 1952 occupation of the section across the 

 Labrador Sea were then plotted and the stations fell into three groups. 

 Stations on the Labrador shelf formed one group in which the phos- 

 phorus concentration was constant but about 0.3 Mga/L higher than 

 the Labrador Current water in the Grand Banks region. The 

 stations in the central Labrador Sea and West Greenland Current 

 formed a second group similar to but slightly lower in concentration 

 than the mixed water of the Grand Banks region. Four stations, 

 two on each side of the central Labrador Sea, formed a third group 

 in which the concentration was the lowest of the entire section. 

 Figure 41 shows average curves representing these groups along 

 with the Grand Banks curves for comparison. The data for the 

 1953 occupation of the section across the Labrador Sea have been 

 similarly treated and the results shown in figure 42. Each of the 

 three groups showed lower concentrations in 1953 than in 1952 but 

 the greatest change was in the Labrador Current water.^ In 1952 



8 CD where te is the temperature a water particle would have if the particle were adiabatically reduced to 

 atmospheric pressure, and where tne is l.oon (density-1) at atmospheric pressure and temperature t». 



'The decided differences in the concentration of total phosphorus in the Labrador Current between 

 the Labrador coast and the Grand Banks region the same year (July and May) and between 1952 and 1953 

 in the same location ofT South Wolf Island at the same time of year brings up additional unanswered ques- 

 tions as to variations with time and the mechanisms by which the concentration is altered. Remembering 

 that the samjjles from the Grand Banks region were taken from locations distant from land and that those 

 off South Wolf Island were taken from locations relatively near the beach it is suggested that the phosphorus 

 concentration may be increased locally by fecal products from birds being washed into the sea from adjacent 

 rookeries and from seals which whelp on the ice over the shelf. 



88 



