. N FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV DEC ,. JAN FEB MAR APR_ ' \9ziT~ '926 Fig. io. Monthly averages of phosphate content in the surface water at Grytviken, South Georgia in 1925-6. The two surveys of November 1930 and 1933 (Table IV) give an indication of the annual variation of phosphate in the surface layer. If we attempt to compare these November results by reducing the number of stations made in 1930 so that the positions of the stations in the 2 years are more nearly comparable, we find that twenty- three stations in 1930 give an average of 92 mg. for the 0-100 m. layer compared
. N FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV DEC ,. JAN FEB MAR APR_ ' \9ziT~ '926 Fig. io. Monthly averages of phosphate content in the surface water at Grytviken, South Georgia in 1925-6. The two surveys of November 1930 and 1933 (Table IV) give an indication of the annual variation of phosphate in the surface layer. If we attempt to compare these November results by reducing the number of stations made in 1930 so that the positions of the stations in the 2 years are more nearly comparable, we find that twenty- three stations in 1930 give an average of 92 mg. for the 0-100 m. layer compared with an average of 109 for twelve stations in 1933. Possible factors which might be responsible for the difference of 17 mg. in these 2 years are difference of average date of the stations involved, meteorological differences, amount of phytoplankton and date of main out- burst in each year, and hydrological differences in the surface layers. The average date the twenty-three stations taken in 1930 which correspond with the positions of the twelve stations of 1933, was 17 November as opposed to 30 November in 1933. In the absence of exact information as to the dates of the main outburst in the 2 years, the fact that the average date of the survey in 1930 was 13 days earlier than in 1933 would tend to argue that the phosphate content of the surface layer should have been greater in 1930 than in 1933 because the phosphate content decreases towards the summer. Thus the factor due to the difference of date of the two surveys should have given rise to more phosphate being removed in 1933 by phytoplankton activities, whereas the surface layer was found to contain more phosphate in 1933 than in 1930. In the opinion of Dr Hart
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