PARTICULATE AND DISSOLVED ORGANIC CARBON IN OCEANS 217 



Bacteria could be eliminated or reduced by at least two orders of magnitude (as 

 indicated by plate tests) by triple filtration or treatment with dichromate or 

 cyanide. In such cases there was no initial peak and only a slight increase in 

 particulate carbon to an average level of 0.10 mg C/liter. 



Discussion of Experiments 



Bubbling experiments show that flakes can be formed which are indistin- 

 guishable from those found in nature, and surface wave action could provide a 

 significant means of converting small particles and dissolved materials into larger 

 particles that contain both protein and carbohydrate and could be a significant 

 food item. Experimentally produced particles have been shown to support the 

 growth of Artemia, 8 and evidence about utilization of naturally occurring 

 particulate matter has been examined. 



However, there is an enigma here, in that flakes are also found in deep ocean 

 waters. They have a slow sinking rate and could hardly have been derived 

 directly from the surface layer without consumption or dissolution in passage. 

 Possibly there is an as yet unknown mode of formation, or possibly additional 

 adsorption from the filter-passing fraction maintains their integrity. 



As for the experiments on bacterial aggregation, the initial cycle of bacterial 

 growth is regarded as an artifact of enclosure in experimental bottles, but the 

 later steady state closely corresponds with conditions in nature. One of the big 

 surprises in early investigation of the distribution of particulate organic carbon 

 was that it did not decrease markedly from mid-depths on down. One would 

 expect it to decline gradually with depth because of gradual consumption, but 

 the kind of dynamic balance observed in experiments, which tends to maintain a 

 sensibly constant concentration despite some cropping, would help to rationalize 

 this distribution. 



REFERENCES 



1. G. A. Riley, Particulate Organic Matter in Seawater, Advan. Mar. Biol., 8: 1-118 (1970). 



2. D. C. Gordon, Some Studies on the Distribution and Composition of Particulate Organic 

 Carbon in the North Atlantic Ocean, Deep-Sea Res., 17: 233-243 (1970). 



3. P. J. Wangersky, in preparation. 



4. O. Holm-Hansen, J. D. H. Strickland, and P. M. Williams, A Detailed Analysis of 

 Biologically Important Substances in a Profile off Southern California, Limnol. 

 Oceanogr., 11: 548-561 (1966). 



5. K. Nakajima, Suspended Particulate Matter in the Western North Pacific Ocean, Ph. D. 

 Thesis, Hokkaido University, 1971. 



6. G. Dal Pont and B. Newell, Suspended Organic Matter in the Tasman Sea, Aust. J. Mar. 

 Freshwater Res., 14: 155-163 (1963). 



7. L. R. Pomeroy and R. E. Johannes, Occurrence and Respiration of Ultraplankton in the 

 Upper 500 Meters of the Ocean, Deep-Sea Res., 15: 381-391 (1968). 



8. N. Handa, Dissolved and Particulate Carbohydrates, in Organic Matter in Natural Waters, 

 Symposium Proceedings, 1967, pp. 129-152, D. W. Hood (Ed.), Institute of Marine 

 Biology, University of Alaska, 1970. 



