Origin and removal of organic particles

Particulate organic matter can be brought by rivers from land weathering or by atmospheric inputs to the oceans, but the major part seems to originate from in situ production of living organisms. 

The atmospheric inputs are more widely dispersed and influence the whole ocean. The input of oiganic carbon by way of precipitation was estimated at 2.2 X 10 g C yr (Williams, 1971), but it can also be calculated 

the sea can apparently supply sufficient material to account for the carbon in rain, although no information exists concerning the efficiency of the transfer from the bubble bursting to the rainfall. It would appear therefore, that the atmospheric inputs enrich the sea with particles, while the surface layer increases the aerosol content of the atmosphere. 

Fragments of organized tissues observed in the euphotic zone (Gordon, 1970a), are scarce in deep waters. In the previous chapter we saw that they represent only 3—5% of the particles present in surface waters. Faecal pellets are present in deep waters but due to their high settling rate it is difficult to recover this material on filters. 

Experiments on water filtered through 0.22-pm filters showed a decreasing yield, pointing out the role of bacteria. This may explain that particle formation is rapidly inhibited unless a removable process is active in the water. Nevertheless, the phenomenon remains operative even in sterilized samples. 

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