542 CYCLES OF ORGANIC AND INORGANIC SUBSTANCES 



nitrogen and phosphorus and other elements important in biology, 

 such as copper, manganese, cobalt, and iron, as has been so ably 

 summarized by Harvey (1955). The quantitative distribution of 

 the major constituents is best known by the inorganic compounds 

 of the total phosphorus. As an example, I draw your attention to 

 the lengthy description of the P04^~ - P concentrations in the 

 South Atlantic (Wattenberg, 1957). 



The respiration processes of zooplankton and bacteria and the 

 processes which bring nutritnt-rich water to the surface are of 

 particular interest. Everybody knows the areas of upwelling in 

 the ocean. The activity of the large currents should also receive 

 special attention, e.g., because on their left-hand boundary in the 

 northern hemisphere, deep water is brought to the surface layers. 

 Thus, there is a eutrophic zone closely connected with mixing 

 caused by these currents. We might add that the role of heavy 

 storms of long duration in the ocean should not be underestimated 

 in the part they play in maintaining the supply of nutrients. In 

 addition, we urgently need better methods of analysis for the 

 different components of total phosphorus and for total nitrogen in 

 ionic solution. These new techniques are essential if we are to 

 make analyses on shipboard in sufficient numbers. 



One question mentioned by Lucas (p. 499) is of the greatest 

 importance, namely the role of organic substances in solution. 

 Their activity takes place in two different ways. They may 

 contribute to the nutrition of filter-feeding animals only when 

 adsorbed on suspended particles. They become concentrated there 

 and then may serve as the foci for the development of a population 

 of bacteria. Secondly, organic substances may act as inhibiting 

 factors as shown by Steemann Nielsen (1955) and by E. G. 

 j0rgensen (1956). 



Light 



We know the role of light, the fourth component, as the source of 

 energy for the production of organic matter and for the photo- 

 tropic orientation of animals and plants in an aquatic environment. 

 Jerlov (1951) has done much good work in this field. We would, 

 however, be very happy from the viewpoint of basic productivity 



