metals with inorganic ions and organic ligands is certainly critical to 

 the biological availabihty of the metals. These coordinations are in 

 turn altered by changes brought about by biological processes, such as 

 pH changes accompanying photosynthesis and respiration, and by 

 biologically produced chelators. 



The development and application of appropriate analytical methods 

 is a necessary prerequisite to the development of inventories of chemical 

 variables. Many sophisticated, sensitive, rapid, and automatic analytical 

 methods have been developed in recent years, and we can now estimate 

 the levels of many constituents of seawater that were unknown a few 

 years ago. Nonetheless, the need for new techniques continues, es- 

 pecially in areas of biologically active substances, chelating agents, 

 and the specific estimation of chemical species — particularly in reference 

 to the state of metals in solution. Advances in qualitative organic analy- 

 sis seem urgently needed. 



Our understanding of the biological processes that alter the chemistry 

 of the ocean, their mechanisms and their rates, tends to lag behind the 

 inventory of chemical variables. Good progress has been made in some 

 areas. The changes in dissolved oxygen, carbon dioxide, and the con- 

 centration of nutrients during photosynthesis and respiration are rea- 

 sonably well understood and correlated. The complications of the 

 additive effects of these life processes and of advection and diffusion 

 on local changes in concentrations are sometimes amenable to explana- 

 tion and modeling. With the advent of routine methods that yield inven- 

 tories of chlorophyll, the phytoplankton biomass responsible for photo- 

 synthesis could be systematically estimated and limits could be placed 

 on the photosynthetic potential of phytoplankton populations. The 

 introduction of the carbon- 14 method for estimating rates of photo- 

 synthesis and extensive studies of the photosynthetic process (generally 

 not carried out by oceanographers) have provided considerable insight 

 into the mechanism of this basic process. 



It is probably the exception rather than the rule to have a good work- 

 ing knowledge of the biological processes that produce measurable 

 changes in the chemistry of the ocean. Historically, the changes more 

 often have been measured, and from them reconstruction of the bio- 

 logical processes producing those changes has been attempted. In some 

 cases, one can now chemically characterize or estimate the potential 

 of a biomass to carry out a biochemical process (through enzyme activity 

 assays), and following the research required to relate the biochemical 

 potential and the pertinent environmental parameters, one can estimate 

 in-situ rates of processes, such as metabolic oxygen consumption. It 

 is probably accurate and pertinent to point out that the evaluation of 

 advective, diffusive, and biological terms in the equation for the local 

 time change in chemical variable has always proved too complex to 



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