Session B 



Chemical Fluxes Through 

 the Marine Environment, Including Air-Sea 

 and Sediment-Sea Exchanges 



Dr. Edward D. Goldberg, Discussion Leader 



INTRODUCTION 



How much material is being added to the present-day ocean by each 

 of the various sources, and how much is being removed to each of the 

 various sinks? For which components are these addition and removal 

 rates changed as functions of time? These questions serve as a basis 

 for investigating fluxes in the marine environment relative to further 

 understanding chemical oceanography. 



We must know how uniform the composition of seawater has been 

 over geologic time intervals to interpret earth history from a study of 

 ancient marine sediments. We must know the fates of various natural 

 constituents added to the marine environment to predict how the ocean 

 will respond to materials introduced by man. 



A simple calculation using the area of the earth's surface covered by 

 the ocean and the average depth of the ocean gives the volume of the 

 ocean. The volume of river water added to the ocean each year is more 

 difficult to determine, but recent estimates are in reasonable agreement. 

 It appears that present-day river inflow would equal the volume of the 

 ocean in about 40,000 years. Hence, water cycles from ocean to atmo- 

 sphere and back vary rapidly on a geologic time scale. 



The total dissolved salt content of seawater can be easily and ac- 

 curately determined and is found to average about 35,000 ppm. The 

 average total dissolved salt content of river water is much more difficult 

 to estimate and is deserving of additional study, but recent estimates 

 cluster around 115 ppm. Assuming no losses from the ocean through 

 sedimentation, and with seawater about 300 times saltier than average 

 river water, 300 transfer cycles from the continents to the oceans would 

 be required to produce seawater salinity. This would take 300 x 40,000 

 years = 12 million years, which is a short time, geologically. 



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