SCOPE AND METHODS OF THE CHEMICAL INVESTIGATIONS 



INTRODUCTION 



The chemical program of the Carnegie was organized 

 primarily with a view of gaining information concerning 

 the nature of the biological environment in the regions 

 traversed, although some of the chemical data obtained 

 can be used as Indicators of water movements. The 

 chemical constituents determined include hydrogen ions, 

 phosphate, silicate, and dissolved oxygen. Salinities 

 were also determined but, since these were used princi- 

 pally for the study of the physical properties of the 

 water, the discussion of them has been included in an- 

 other report. 



It has long been known that the major constituents 

 of the dissolved salt in sea water occur in constant pro- 

 portion, and that their quantities may be computed from 

 the salinity or from one of its components- -the chloride 

 for example. Many of the minor constituents, especial- 

 ly those involved in biological activities, do not occur in 

 constant oroDortion to the total salt, and their concen- 

 tration, as in the case of phosphate, may vary by several 

 hundred per cent. Among the substances that play an 

 important role in the metabolic cycle of the sea are 



nitrates, phosphates, silicates, carbon dioxide, and 

 oxygen. The first four are extracted from the water by 

 plants and liberated in the final decomposition of organ- 

 ic remains. Carbon dioxide is absorbed by plants and 

 oxygen is liberated during photosynthesis whereas the 

 reverse occurs during the respiration of plants and ani- 

 mals. Because of their intimate relation to the life In 

 the sea, and because of the great variability in their 

 quantities, it is essential to determine these substances 

 in various localities and at various depths in order to 

 obtain an adequate picture of the biological environment 

 in any part of the sea. 



Aside from their importance m oiological studies 

 and as indicators of water movements and the origin of 

 water masses, some of the substances determined as- 

 sume a prominent part in geological processes taking 

 place on the sea bottom. For example, silitate relation- 

 ships are involved in the deposition of diatom shells; and 

 pH relationships are involved in the solubility of calcium 

 carbonate in sea water. 



HISTORICAL 



Prior to the last cruise of the Carnegie several of 

 the chemical substances concerned with the growth of 

 organisms had been investigated in various parts of the 

 Atlantic, but for the Pacific there was little information 

 available. This was particularly true for the open Pacific 

 for which information was almost entirely lacking. The 

 earliest records of any chemical investigations in the 

 Pacific are those of the Challenger expedition in 1873 to 

 1876 (Dittmar, 1884). The reports of this expedition 

 are classics in the pioneer study of the chemistry of sea 

 water, as well as of other phases of oceanography, but 

 its work was concerned chiefly with the major saline 

 components of sea water. Dissolved oxygen was deter- 

 mined on a few isolated water samples but the results 

 are not adequate for any general conclusions. The 



Planet (Brennecke, 1909) in 1906 to 1907 made some 

 chemical investigations of the water below the surface 

 between New Guinea and Hong Kong. A. G. Mayor (1919, 

 1922) determined the hydrogen-ion concentration of the 

 surface water between San Francisco and the Hawaiian 

 and the Samoan islands. The Dana (Schmidt, 1925, 

 1929) determined the dissolved oxygen at various depths 

 in the Gulf of Panama in 1922. Ito (1928) in 1926 de- 

 termined the hydrogen- ion concentration of water from 

 various levels between New Guinea and Japan. In cer- 

 tain coastal areas more complete investigations had 

 been carried out: for example, in the Strait of Georgia 

 by the Pacific Biological Station of the Biological Board 

 of Canada; in the Puget Sound region by the University 

 of Washington; along the coast of southern California by 

 the Scripps Institution of Oceanography of the Universi- 

 ty of California; and off Monterey cooperatively by the 

 Hopkins Marine Station of Stanford University, the Mu- 

 seum of Comparative Zoology of Harvard University, 

 the Scripps Institution of Oceanography, and the Cali- 



fornia Division of Fish and Game. Most of these local- 

 ities cannot be considered as representing the open Pa- 

 cific, however, and the chemical conditions in virtually 

 the whole of this ocean were practically unknown until 

 investigated by the Carnegie . 



Subsequent to the Carnegie's cruise, further work 

 has been carried out in the coastal areas mentioned by 

 the Japanese in the waters adjacent to Japan, and by the 

 Great Barr^ier Reef expedition in the Great Barrier 

 Reef region of Australia. The following expeditions ana' 

 institutions have investigated certain chemical condi- 

 tions in the open Pacific: the Willebrord Snellius expe- 

 dition in the Dutch East Indies; the Dana expedition 

 from Panama to the East Indies; the Japanese training 

 ship, the Sintoku Maru , from Kobe to San Diego; the 

 University of Washington in the Gulf of Alaska and, in 

 cooperation with the United States Navy, in the Bering 

 Sea; and the Scripps Institution of Oceanography in co- 

 operation with the United States Navy off the coast of 

 Central America and from the Aleutian Islands to the 

 Hawaiian Islands. To the results of most of these in- 

 vestigations reference will be made in the Carnegi e 

 chemistry reports. 



The Carnegie's investigations in the Pacific are by 

 far the most extensive ever undertaken in this ocean. 

 One hundred and twenty-eight stations were occupied 

 and samples for chemical analyses were taken from 

 about twenty levels at each station, extending from the 

 surface usually to several thousand meters. At nearly 

 all the stations phosphate and hydrogen ions were deter- 

 mined and at the last thirty-three stations also silicate 

 and dissolved oxygen. As a result, a fairly complete 

 picture was obtained of the distribution, vertical and 

 horizontal, of plant nutrients in a large part of the North 

 Pacific as well as in the tropical and southeastern South 



