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GORDON A. RILEY
formed in deep ocean water, although it is not obvious how they could
be provided with the necessary energy for organic synthesis or moulded
into the characteristic leaf-like shape under these circumstances.
However, within the general size range of 15-35 p, flakes are the
most abundant particles in deep water (Gordon, 1970a). Gordon also
showed that most of their protein can be removed by enzymatic
hydrolysis, and present work indicates that they are readily attacked
by bacteria in experiments of some weeks’ duration. They are found
in deep water in various stages of decay, and some look as fresh as
newly produced particles. If they were produced only in the surface
layer and sank through a typical vertical column of 4000m, the
residence time would be more than 50 years. Since some of them are
being degraded by bacteria, a t least to the point of virtual invisibility
if not complete destruction, one would expect a decrease with depth,
but this is not the case. There seems to be no reasonable alternative
to some mode of formation in deep water.
The other type of in situ aggregation, by simple amalgamation of
smaller particles, is not so mysterious, although certain aspects have
not been fully worked out. The study of early stages of formation by
Sheldon et al. (1967) leaves some doubt as to whether the initiation of
the process requires bacteria or is entirely a physical process. The
later production of large quantities of aggregated material requires a
bacterial flora in the experiments that have been described. The general
principles have been known for years and have been used to practical
advantage by sanitary engineers in the treatment of sewage. The
problem appears to be simply one of reducing the electrical charges
which ordinarily keep particles dispersed, and sewage effluents are
aggregated and precipitated by chemical or bacterial treatments which
accomplish this purpose.
I n summary, observations and experiments with natural sea water
indicate that particulate matter can be formed on air-water interfaces
and within the water column by aggregation of smaller particles, together with adsorption of colloidal and probably dissolved organic
material. Adsorption of organic matter on inorganic particles has been
demonstrated. Biochemical synthesis and incorporation of inorganic
ions appear to be important. Formation of particles on air-water interfaces by compression of monomolecular films remains as a possible
mode of formation but has not been undeniably established. The
complexities of the natural sea water system have placed several constraints on attempts to sort out the various processes that are involved.
Attempts to examine the physical chemistry and biochemistry of
simplified artificial systems have been abortive because of difficulties
GORDON A. RILEY
formed in deep ocean water, although it is not obvious how they could
be provided with the necessary energy for organic synthesis or moulded
into the characteristic leaf-like shape under these circumstances.
However, within the general size range of 15-35 p, flakes are the
most abundant particles in deep water (Gordon, 1970a). Gordon also
showed that most of their protein can be removed by enzymatic
hydrolysis, and present work indicates that they are readily attacked
by bacteria in experiments of some weeks’ duration. They are found
in deep water in various stages of decay, and some look as fresh as
newly produced particles. If they were produced only in the surface
layer and sank through a typical vertical column of 4000m, the
residence time would be more than 50 years. Since some of them are
being degraded by bacteria, a t least to the point of virtual invisibility
if not complete destruction, one would expect a decrease with depth,
but this is not the case. There seems to be no reasonable alternative
to some mode of formation in deep water.
The other type of in situ aggregation, by simple amalgamation of
smaller particles, is not so mysterious, although certain aspects have
not been fully worked out. The study of early stages of formation by
Sheldon et al. (1967) leaves some doubt as to whether the initiation of
the process requires bacteria or is entirely a physical process. The
later production of large quantities of aggregated material requires a
bacterial flora in the experiments that have been described. The general
principles have been known for years and have been used to practical
advantage by sanitary engineers in the treatment of sewage. The
problem appears to be simply one of reducing the electrical charges
which ordinarily keep particles dispersed, and sewage effluents are
aggregated and precipitated by chemical or bacterial treatments which
accomplish this purpose.
I n summary, observations and experiments with natural sea water
indicate that particulate matter can be formed on air-water interfaces
and within the water column by aggregation of smaller particles, together with adsorption of colloidal and probably dissolved organic
material. Adsorption of organic matter on inorganic particles has been
demonstrated. Biochemical synthesis and incorporation of inorganic
ions appear to be important. Formation of particles on air-water interfaces by compression of monomolecular films remains as a possible
mode of formation but has not been undeniably established. The
complexities of the natural sea water system have placed several constraints on attempts to sort out the various processes that are involved.
Attempts to examine the physical chemistry and biochemistry of
simplified artificial systems have been abortive because of difficulties