is the result of our inability to make real-time rate measurements, re- 

 search should be focused on developing our capacity to make such 

 rate measurements, analagous to our present ability to make real-time 

 concentration measurements. 



The rates that must be measured are those of nutrient uptake by plank- 

 ton and nutrient release by bacteria and zooplankton. These processes 

 are modulated by environmental factors such as light, temperature, and 

 pressure, plus biological factors such as biomass, species, and age. 

 Our ability to measure fluxes in and out of living particles is limited to 

 incubation techniques that are based on questionable assumptions, 

 that are not suitable for the study of time-dependent processes, and 

 that are too slow to be compatible with real-time data acquisition systems. 

 The use of enzyme analysis in oceanographic research can relieve this 

 reliance on incubation techniques by substituting in-vitro techniques 

 that are amenable to continuous chemical determination. The use of 

 enzyme analyses to estimate rates of biochemical process depends on 

 the identification of the enzyme system that regulates the process and 

 the measurement of its in-vitro substrate transformation rate, i.e., its 

 activity. These measurements are sensitive and fast, and when properly 

 calibrated, are as accurate as the more classical in-vivo incubation 

 approach. 



In addition, the dynamics of consumption and production of oxygen, 

 carbon dioxide, hydrogen sulfide, nitrogen, hydrogen and methane 

 are also controlled by intracellular enzymes of marine organisms. As 

 a result, real time measurement of the rates of these fluxes and their 

 variation in time and space can only be realized by determining the 

 activity of these enzymes. To implement this research we must: 



1 . Identify the enzyme or enzyme systems that control the utilization 

 and the formation of POi^, NOs", NOj, NHt and Si02. These will prob- 

 ably be phosphatases, nitrate reductase, intrite reductase, and glutamate 

 dehydrogenase, which control the fluxes of P and N. The enzymes 

 regulating silicate fluxes are not known. 



2. Develop analytical techniques to measure the activity of these 

 enzymes and automate and interface the analyses with existing com- 

 puter-controlled data-acquisition systems. 



3. Derive mathematical expressions for the regulatory mechanisms 

 by which light, substrate level, temperature, and physiology control 

 the activity of these enzymes. 



4. Determine the pattern of variation of enzyme activities in the 

 marine environment and relate it to changes of the nutrient fields and 

 to the biological and physical parameters. 



5. Construct both conceptual and mathematical models of the nutri- 

 ent cycles and the processes that control them in: 



a. Upwelling areas 



58 



