26 



CHEMICAL RESULTS OF LAST CRUISE OF CARNEGIE 



part of Section ni. The surface values are 8.31 and 8.23 

 respectively. At other depths the pH corresponds to 

 that at stations 37 and 38 in Section HI. 



Section IV. stations 51 to 45: in the southeastern 

 Pacific extending approximately north and south from 

 latitudes 29° to 5° south between longitudes 115° and 

 105° west. --In this section the surface pH values are 

 lower at the stations nearest the equator than at the sta- 

 tions farther south. Similarly, the change in pH with 

 depth is much more abrupt at the northern than at the 

 southern stations. The minimum pH, between 7.6 and 

 7.7, occurs near 500 meters at the three northern sta- 

 tions and at 1000 to 1800 meters at the other stations in 

 the section, at most of which the pH is slightly over 7.7. 



Section X. stations 51 and 52. and 55 to 60: in the 

 southeastern Pacific, extending southeastward from lat- 

 itude 29° south, longitude 115° west, to latitude 40° 

 south, longitude 98° west. --In this section there is a 

 gradual decrease in the surface pH from above 8.2 at 

 the northwesternmost stations to less than 8.1 at the 

 southeasternmost stations. 



The transition zone and the level at which the mini- 

 mum pH values occur, as well as the pH values in the 

 latter and in the deeper water, resemble those of the 

 southern part of sections III and IV. 



Stations 53 and 54: north of Section X, north of sta- 

 tion 56, east of station 51, south of Easter Island. --The 

 distribution of pH at these stations corresponds to that 

 at the stations to the east (Section X) rather than that at 

 the stations to the south. The surface pH is 8.22, the 

 same as at station 51, and the variation with depth fol- 

 lows closely that at this station. 



Section XI, stations 93 to 71: practically east and 

 west between latitudes 18° and 10° south, from the Sa- 

 moan Islands (longitude 168° west) to Callao, Peru (lon- 

 gitude 78° west). --At the surface the pH increases from 

 east to west as do the temperatures. The lowest pH 

 value (8.13) in this section is found at station 71 near 

 Callao. Toward the west the values increase to more 

 than 8.3 at the stations in the western part of the sec- 

 tion. 



The level of the greatest change in pH with depth is 

 in the upper 100 or 200 meters near the coast but grad- 

 ually deepens toward the west until its lower limit is 

 found at about 500 meters. The minimum values are 

 below pH = 7.7 and are found between 500 and 1000 me- 

 ters in the eastern part of the section, but in the western 

 part they are above 7.7 and occur at depths between 

 about 1000 and 2000 meters. Similarly, in the deep 

 water east of station 85 (longitude 136° west) pH is 

 slightly over 7.7, and west of this station it is above 7.8. 



Section XII, stations 45 to 40: in the equatorial 

 southeastern Pacific, extending approximately along 

 parallel 2° south from longitude 105° west to the South 

 American coast. --At the surface the pH values range 

 from slightly under 8.1 to slightly over 8.2 at station 40. 

 The vertical pH gradient is fairly steep with the mini- 

 mum where the pH values are below 7.7, occurring at 

 depths between 500 and 700 meters. In the deep water 

 the pH is below 7. 7 to the west and somewhat above that 

 in the eastern part of the section. 



Section V. stations 162 to 148 and 134 to 132: ex- 

 tends northeastward from the Samoan Islands (latitude 

 14° south, longitude 168° west) to San Francisco (lati- 

 tude 37° north). --At the surface the pH values at all the 

 stations are comparatively high being over 8.3 at most 

 of the stations and even over 8.4 at a few stations. At a 



few meters below the surface, pH values above 8.4 occur 

 at several stations. 



Except at the center of the section the change in pH 

 with depth is fairly gradual. At station 152 the gradient 

 is exceedingly steep, as is the case with temperature 

 and phosphate and the other substances determined, the 

 bottom of the transition zone being at about 100 meters. 

 From this station toward the northeast and southwest 

 there is a gradual change toward conditions prevailing at 

 the majority of the stations. 



Minimum pH values occur at the depths ranging from 

 500 to 1000 meters from the first stations off the Cali- 

 fornia coast to slightly beyond the equator, but farther 

 south they are found near 1500 meters. 



The minimum pH values range from between 7.6 and 

 7.7 at several stations in the central part of the section 

 to between 7.7 and 7.8 at the stations near each end of 

 the section. In the deep water, below 2000 meters, the 

 pH is usually about 7.8. 



Section VII. stations 139 to 143: more or less north 

 and south in the central North Pacific, following approxi- 

 mately meridian 160° west from the Hawaiian Islands 

 (latitude 22° north) to about latitude 34° north.--At the 

 surface the pH values vary from 8.3 to 8.4, the former 

 value being found to a depth of about 250 meters at sta- 

 tion 140. At this station, however, the change in pH be- 

 low this depth is the most rapid. In general the zone of 

 rapid change in pH extends from 500 to 1800 meters, the 

 minimum values being found between 700 and 1000 me- 

 ters with pH ranging around 7.6. Below the minimum, 

 as in the case of the other sections, pH increases with 

 depth, reaching 7.8 at about 3000 meters. 



Section XIV. stations 140 to 130: from the Hawaiian 

 Islands to San Francisco. --Stations 132 to 134 were 

 discussed under Section V, and stations 139 to 140 under 

 Section VII. 



At the other stations the surface water has a pH be- 

 tween 8.3 and 8.4. The change in pH with depth is fairly 

 gradual and resembles that at most of the two adjoining 

 sections mentioned. The minimum values occur between 

 500 and 1000 meters with values ranging from about 7.7 

 at station 138 to near 7.8 at station 132. In the deeper 

 water the pH varies from 7.8 to 7.9. 



Section XV. stations 142 to 146: an east and west 

 section in the central North Pacific, extends approxi- 

 mately along the parallel 33° north between longitudes 

 161° and 141° west. --This section resembles Section 

 VII, which includes also stations 142 and 143, and most 

 of Section XIV. 



At the surface the pH is over 8.3, the change with 

 depth being fairly gradual and the minimum occurring 

 between 500 and 1000 meters. The minimum values are 

 somewhat lower than at most of the stations in this re- 

 gion, being below 7.6, and in the deeper water the pH is 

 also somewhat lower than at other stations. 



Section VI. stations 130 to 125: in the northeastern 

 Pacific, extending from San Francisco northwestward to 

 a point south of the Gulf of Alaska (latitude 52 ° north, 

 longitude 151° west). --At the surface the pH is relatively 

 low, being about 8.1 at all the stations. At the three sta- 

 tions nearest the American coast, 127 to 129, the transi- 

 tion zone extends to about 500 meters, but northwest of 

 this it gradually rises and at the last station of the sec- 

 tion it is confined to the upper 150 meters. 



The depth of the minimum layer shows a similar 

 change, being at 800 meters at stations 127 to 129 and at 

 about 400 meters at the last station of the section. The 



