Home >> Papers-from-the-department-of-marine-bio-volume-11 >> 3 Effect Of Temperature to Germ Cell Origin In Vertebrates >> Content 0 Sea Wa Di

Content 0 Sea-Wa Di 1 Dv a D the Co

excess, base, found, sea-water and water

'1 DV A D THE CO, CONTENT 0 SEA-WA DI • Tomoe observed that sea-water is alkaline to litmus or rosolic acid. He added a known excess of normal to a liter of sea-water, boiled off the caught it in a known solution of for de i i •i • the total titrated the sea-water back with free alkali, using phenolphthalein as indicator. He found the excess base to be 24 (in our terminology) as a mean value for the parts investigated of the North Atlantic. In titrating with phenolphthalein, the silicates and part of the borates are decomposed (i. e., not re-formed when titrating back), but part of the borates and phosphates act as neutral salts, and we found that the result is about 5 per cent lower than with our method, in which boric and a small amount of phosphoric acid do not affect the result. On the other hand, the results may be too high if too great excess of acid is added or if it is boiled too long, since HC1 - is liable to pass out with the steam. It makes little difference whether HC1 or H,SO4 was added, since HC1 is formed in sea-water from by dissociation of the large excess of chlorides.

Dittmar found that the average excess base of sea-water was about 25. Ina sample of Irish Channel water he found the excess base to be 23 and total 49.7 c.c. per liter.

Tornoe found that average North Atlantic water contained 49.07 c.c. of per liter, and Petterson found that the maximum of all of his samples contained 49.08 c.c. of per liter (the water being drawn from a depth of 55 meters). It may be noticed that Tomoe's average is about the maximum, and probably the great majority of samples were from the depths.

The samples collected by the

Challenger during its cruise of three and a half years were boiled by Buchanan and the boiled off was estimated; then they were kept several years, during which time they probably absorbed some to replace part of that lost; then the total they contained was determined by Dittmar and added to Buchanan's figures. Dole found about 45 c.c. of per liter in Tor

tugas sea-water by a titration method.

Dittmar showed that there is an average of 0.44 per cent more lime in the water near the bottom (due to solution of shells) than at the surface of the sea, which accounts for the increase in excess base with depth. The tables of the Danish Ingolf Expedition show the following variations in excess base near the bottom: South of Iceland and east of the barrier (Rykjanaes Ryg) excess base equals 26, west of the barrier it equals 23.7, and in Davis Strait it equals 23.5, the salinity being about 35 and bearing no relation to excess base. The surface water of Davis Strait averaged 23.6 excess base and 34 salinity. As an exception due to special conditions, Walter and Schirlitz found that the excess base in bottom-water in depressed parts of the Bay of Naples averaged 24, whereas the surface-water averaged nearly 27. Dole found that the excess base in Tortugas water (near surface) varied from 23.7 to 25.7. Ruppin, on the Poseidon expedition, found that the excess base averaged 25, with 35 salinity.

Since the excess base or "alkalinity" of sea-water has been expressed in various ways, the following conversion factors are convenient for converting all results to our terminology: Excess base = 0.8933 X c.c. in normal carbonate.

= 0.4545 X mg. CO2 in normal carbonate.

= 0.588 X mg. OH equivalent to acid used in titration.

The total is often given in milligrams, which may be reduced to cubic centimeters by multiplying by 0.509.