214 RILEY 



inadequate, but the information that has accrued still supports the original 

 postulate. There is as yet no way of estimating how much of the particulate 

 matter in deep water represents residual material originating in shallow water 

 and how much has been added by gradual accretion or has been formed de novo 

 in deep water. However, the time scales that are involved would suggest that 

 only the most inert materials could survive the long passage from surface to 

 bottom. 



Finally, estimates of the sedimentation rate of particulate matter on the 

 deep ocean bottom are approximately equal to the estimated food requirements 

 of the benthic fauna. 1 Most of this organic matter that settles out is utilized on 

 the bottom, for the organic content of bottom sediments is far less than that of 

 suspended particulates. This is not difficult to understand, for compaction of the 

 settled material creates a relatively high concentration that should make it more 

 vulnerable both to sediment feeders and to the kind of bacteria that are required 

 to oxidize refractory organic substances with the mediation of dissolved organics 

 that undoubtedly are more abundant in interstitial water than in the overlying 

 water column. As sediment gradually accumulates on the bottom, the long, slow 

 process of decomposition continues, so that the organic content declines with 

 depth of burial until only a small fraction of the amount originally delivered to 

 the sea floor remains permanently incarcerated. 



APPENDIX 

 Experimental Information 



Baylor, Sutcliffe, and Hirschfeld 9 and Sutcliffe, Baylor, and Menzel 33 

 reported that organic particles could be produced experimentally by passing a 

 stream of bubbles through a column of filtered seawater. Riley 10 confirmed 

 these results and reported that natural seawater contains flakes of particulate 

 organic matter that are visually indistinguishable from the ones produced 

 experimentally. This was part of a general study of the kinds and quantities of 

 nonliving organic matter occurring in Long Island Sound. Subsequent 

 papers ' ' examined the distribution of organic matter in open waters of the 

 Atlantic Ocean and reported further experiments on particle formation. The 

 quantity obtained by bubbling surface seawater samples from impoverished 

 areas, such as the Sargasso Sea, generally was less than the yield from rich 

 inshore waters but was in turn significantly larger than the amount that could be 

 produced from deep-ocean samples. There were suggestions in this early work 

 that the largest quantities of nonliving organic matter and the greatest potential 

 for experimental production were in places and times of major plankton growth 

 and abundance. Large yields were also obtained by bubbling filtered media in 

 which algal cultures had been grown. 3 Results implied that freshly produced 

 metabolic products can be converted to particles more efficiently than in the 

 case of the older dissolved matter ordinarily present. 



