Viscosity 



The viscosity of sea water Is slightly greater than that of fresh water (0.0893 

 poises at 25 C) and Increases gradually with an increase in salinity and to a much 

 greater extent with a decrease in temperature. At a salinity of 35 o/oo, for example, 

 the Increase of viscosity is almost two-fold for a temperature drop from 25 to 

 centigrade. 



Pressure 



Hydrostatic pressure increases by about 1 atmosphere for each 32.8-foot 

 increase in depth, and shows a range from zero at the surface to some 1, 100 atmospheres 

 at the greatest known depth of 36, 000 feet. The mean ocean depth of all the oceans 

 and adjacent seas Is about 12,500 feet. 



Light 



Light is absorbed rapidly when passing through the surface waters of the sea 

 and the intensity falls off with depth. In the clearest open ocean water, light Is 

 perceptible to a depth of 2, 300 feet. In average open ocean water, light of 

 selective wavelength bands Is perceptible to a depth of 1,000 feet, and in turbid 

 coastal waters to 200 feet. 



Suspended Organic Matter 



Sea water contains a small quantity (1.2 to 2.0 mg of carbon per liter) of 

 dissolved and suspendea organic matter, which Is derived from the excreta of 

 living organisms and their decomposed tissues after death. 



Dissolved Gases 



The dissolved gases of particular biological interest are oxygen and carbon 

 dioxide. The dissolved oxygen content of ocean water varies from to 8.5 ml/liter 

 STP (standard temperature and pressure). It is greater in the surface layers where free 

 exchange with the atmosphere can take place than in the subsurface waters, which 

 obtain their oxygen through mixing, wind action, etc. In certain closed seas and 

 basins In which there is deficient circulation, the bottom layers become stagnant 

 and the oxygen concentration falls to zero. Hydrogen sulfide and other products 

 of putrlfactlve decomposition such as methane may be present in such areas. The 

 carbon-dioxide concentration In sea water varies from 34 to 56 ml/liter. It is 

 present as free CO2 and H2CO3, but the greater part of carbon dioxide is present 



