PARTICULATE ORGANIC MATTER IN SEA WATER
4!)
previous conclusions that the rate of particle formation is rapid at first
but cannot be maintained unless the particles are removed.
Certain aspects of experimental particle formation in sea water
have not yet been thoroughly studied. For example, quantitative
studies of the effects of variations in air flow and bubble size are still
lacking. More important, the physical chemistry of the aggregation
process remains obscure, and information about the kinds of compounds involved is little more than anecdotal. These basic problems
probably could be studied more effectively with artificial sea water of
known composition, both organic and inorganic, than with natural sea
water. Wangersky (1965) began a programme of this sort but was
unable to continue it because of difficulties in removing organic contaminants from his distilled water. The problem still awaits study,
and little further progress can be made until the basic facts become
clearer.
A second kind of problem, of a different and perhaps even more
difficult sort, is the assessment of natural rates of particle production
at the sea surface and attempts to synthesize laboratory results and
field observations into a coherent picture of what is actually happening
at the sea surface. These problems will be considered in a later discussion, but the discussion will raise more questions than it answers.
B. In situ production and utilization
1. Organic carbon
Riley et al. (1965) proposed the hypothesis that the lack of a systematic vertical gradient in particulate matter in the deep sea could best
be explained as an expression of a dynamic balance between utilization
and further adsorption from the filterable fraction. To test whether
such adsorption might occur, particles were produced artificially by
bubbling, and small quantities of this water were seeded into carboys
of filtered deep sea water and were allowed to stand without disturbance
for a day. The carboys were then filtered for analyses of particulate
carbon, and there was in fact more carbon present than had been
added.
Further experiments involved additions of experimentally produced
particles and natural particulate matter to filtered deep sea water, and
the water was allowed to stand for several days. The same kind of
results was obtained, but there was also a significant accumulation of
carbon in controls that were simply filtered, with no addition of substrate for adsorption. This suggested the existence of some sort of
process whereby particles could be produced by aggregation of filter
4!)
previous conclusions that the rate of particle formation is rapid at first
but cannot be maintained unless the particles are removed.
Certain aspects of experimental particle formation in sea water
have not yet been thoroughly studied. For example, quantitative
studies of the effects of variations in air flow and bubble size are still
lacking. More important, the physical chemistry of the aggregation
process remains obscure, and information about the kinds of compounds involved is little more than anecdotal. These basic problems
probably could be studied more effectively with artificial sea water of
known composition, both organic and inorganic, than with natural sea
water. Wangersky (1965) began a programme of this sort but was
unable to continue it because of difficulties in removing organic contaminants from his distilled water. The problem still awaits study,
and little further progress can be made until the basic facts become
clearer.
A second kind of problem, of a different and perhaps even more
difficult sort, is the assessment of natural rates of particle production
at the sea surface and attempts to synthesize laboratory results and
field observations into a coherent picture of what is actually happening
at the sea surface. These problems will be considered in a later discussion, but the discussion will raise more questions than it answers.
B. In situ production and utilization
1. Organic carbon
Riley et al. (1965) proposed the hypothesis that the lack of a systematic vertical gradient in particulate matter in the deep sea could best
be explained as an expression of a dynamic balance between utilization
and further adsorption from the filterable fraction. To test whether
such adsorption might occur, particles were produced artificially by
bubbling, and small quantities of this water were seeded into carboys
of filtered deep sea water and were allowed to stand without disturbance
for a day. The carboys were then filtered for analyses of particulate
carbon, and there was in fact more carbon present than had been
added.
Further experiments involved additions of experimentally produced
particles and natural particulate matter to filtered deep sea water, and
the water was allowed to stand for several days. The same kind of
results was obtained, but there was also a significant accumulation of
carbon in controls that were simply filtered, with no addition of substrate for adsorption. This suggested the existence of some sort of
process whereby particles could be produced by aggregation of filter